draft-ietf-l2vpn-evpn-03.txt   draft-ietf-l2vpn-evpn-04.txt 
skipping to change at page 1, line 19 skipping to change at page 1, line 19
W. Henderickx W. Henderickx
S. Boutros F. Balus S. Boutros F. Balus
K. Patel Alcatel-Lucent K. Patel Alcatel-Lucent
S. Salam S. Salam
Cisco Aldrin Isaac Cisco Aldrin Isaac
Bloomberg Bloomberg
J. Drake J. Drake
R. Shekhar J. Uttaro R. Shekhar J. Uttaro
Juniper Networks AT&T Juniper Networks AT&T
Expires: August 25, 2013 February 25, 2013 Expires: January 15, 2014 July 15, 2013
BGP MPLS Based Ethernet VPN BGP MPLS Based Ethernet VPN
draft-ietf-l2vpn-evpn-03 draft-ietf-l2vpn-evpn-04
Status of this Memo Status of this Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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Copyright and License Notice Copyright and License Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Abstract Abstract
This document describes procedures for BGP MPLS based Ethernet VPNs This document describes procedures for BGP MPLS based Ethernet VPNs
(E-VPN). (EVPN).
Table of Contents Table of Contents
1. Specification of requirements . . . . . . . . . . . . . . . . . 5 1. Specification of requirements . . . . . . . . . . . . . . . . . 5
2. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. BGP MPLS Based E-VPN Overview . . . . . . . . . . . . . . . . . 6 5. BGP MPLS Based EVPN Overview . . . . . . . . . . . . . . . . . 6
6. Ethernet Segment . . . . . . . . . . . . . . . . . . . . . . . 7 6. Ethernet Segment . . . . . . . . . . . . . . . . . . . . . . . 7
7. Ethernet Tag . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. Ethernet Tag . . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1 VLAN Based Service Interface . . . . . . . . . . . . . . . . 9 7.1 VLAN Based Service Interface . . . . . . . . . . . . . . . . 9
7.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 9 7.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 9
7.2.1 Port Based Service Interface . . . . . . . . . . . . . . 10 7.2.1 Port Based Service Interface . . . . . . . . . . . . . . 10
7.3 VLAN Aware Bundle Service Interface . . . . . . . . . . . . 10 7.3 VLAN Aware Bundle Service Interface . . . . . . . . . . . . 10
7.3.1 Port Based VLAN Aware Service Interface . . . . . . . . 10 7.3.1 Port Based VLAN Aware Service Interface . . . . . . . . 10
8. BGP E-VPN NLRI . . . . . . . . . . . . . . . . . . . . . . . . 10 8. BGP EVPN NLRI . . . . . . . . . . . . . . . . . . . . . . . . . 10
8.1. Ethernet Auto-Discovery Route . . . . . . . . . . . . . . . 11 8.1. Ethernet Auto-Discovery Route . . . . . . . . . . . . . . . 11
8.2. MAC Advertisement Route . . . . . . . . . . . . . . . . . 12 8.2. MAC Advertisement Route . . . . . . . . . . . . . . . . . 12
8.3. Inclusive Multicast Ethernet Tag Route . . . . . . . . . . 12 8.3. Inclusive Multicast Ethernet Tag Route . . . . . . . . . . 12
8.4 Ethernet Segment Route . . . . . . . . . . . . . . . . . . . 13 8.4 Ethernet Segment Route . . . . . . . . . . . . . . . . . . . 13
8.5 ESI Label Extended Community . . . . . . . . . . . . . . . . 13 8.5 ESI Label Extended Community . . . . . . . . . . . . . . . . 13
8.6 ES-Import Route Target . . . . . . . . . . . . . . . . . . . 14 8.6 ES-Import Route Target . . . . . . . . . . . . . . . . . . . 14
8.7 MAC Mobility Extended Community . . . . . . . . . . . . . . 14 8.7 MAC Mobility Extended Community . . . . . . . . . . . . . . 14
8.8 Default Gateway Extended Community . . . . . . . . . . . . . 15 8.8 Default Gateway Extended Community . . . . . . . . . . . . . 15
9. Multi-homing Functions . . . . . . . . . . . . . . . . . . . . 15 9. Multi-homing Functions . . . . . . . . . . . . . . . . . . . . 15
9.1 Multi-homed Ethernet Segment Auto-Discovery . . . . . . . . 15 9.1 Multi-homed Ethernet Segment Auto-Discovery . . . . . . . . 15
9.1.1 Constructing the Ethernet Segment Route . . . . . . . . 15 9.1.1 Constructing the Ethernet Segment Route . . . . . . . . 15
9.2 Fast Convergence . . . . . . . . . . . . . . . . . . . . . . 16 9.2 Fast Convergence . . . . . . . . . . . . . . . . . . . . . . 16
9.2.1 Constructing the Ethernet A-D Route per Ethernet 9.2.1 Constructing the Ethernet A-D Route per Ethernet
Segment . . . . . . . . . . . . . . . . . . . . . . . . 16 Segment . . . . . . . . . . . . . . . . . . . . . . . . 16
9.2.1.1. Ethernet A-D Route Targets . . . . . . . . . . . . 17 9.2.1.1. Ethernet A-D Route Targets . . . . . . . . . . . . 17
9.3 Split Horizon . . . . . . . . . . . . . . . . . . . . . . . 17 9.3 Split Horizon . . . . . . . . . . . . . . . . . . . . . . . 17
9.3.1 ESI Label Assignment . . . . . . . . . . . . . . . . . . 18 9.3.1 ESI Label Assignment . . . . . . . . . . . . . . . . . . 18
9.3.1.1 Ingress Replication . . . . . . . . . . . . . . . . 18 9.3.1.1 Ingress Replication . . . . . . . . . . . . . . . . 18
9.3.1.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . 19 9.3.1.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . 19
9.3.1.3. MP2MP LSPs . . . . . . . . . . . . . . . . . . . . 20
9.4 Aliasing and Backup-Path . . . . . . . . . . . . . . . . . . 20 9.4 Aliasing and Backup-Path . . . . . . . . . . . . . . . . . . 20
9.4.1 Constructing the Ethernet A-D Route per EVI . . . . . . 21 9.4.1 Constructing the Ethernet A-D Route per EVI . . . . . . 21
9.4.1.1 Ethernet A-D Route Targets . . . . . . . . . . . . . 22 9.4.1.1 Ethernet A-D Route Targets . . . . . . . . . . . . . 22
9.5 Designated Forwarder Election . . . . . . . . . . . . . . . 22 9.5 Designated Forwarder Election . . . . . . . . . . . . . . . 22
10. Determining Reachability to Unicast MAC Addresses . . . . . . 24 9.6. Interoperability with Single-homing PEs . . . . . . . . . . 24
10. Determining Reachability to Unicast MAC Addresses . . . . . . 25
10.1. Local Learning . . . . . . . . . . . . . . . . . . . . . . 25 10.1. Local Learning . . . . . . . . . . . . . . . . . . . . . . 25
10.2. Remote learning . . . . . . . . . . . . . . . . . . . . . 25 10.2. Remote learning . . . . . . . . . . . . . . . . . . . . . 26
10.2.1. Constructing the BGP E-VPN MAC Address Advertisement . 25 10.2.1. Constructing the BGP EVPN MAC Address Advertisement . 26
10.2.2 Route Resolution . . . . . . . . . . . . . . . . . . . 27 10.2.2 Route Resolution . . . . . . . . . . . . . . . . . . . 28
11. ARP and ND . . . . . . . . . . . . . . . . . . . . . . . . . . 28 11. ARP and ND . . . . . . . . . . . . . . . . . . . . . . . . . . 29
11.1 Default Gateway . . . . . . . . . . . . . . . . . . . . . . 29 11.1 Default Gateway . . . . . . . . . . . . . . . . . . . . . . 29
12. Handling of Multi-Destination Traffic . . . . . . . . . . . . 29 12. Handling of Multi-Destination Traffic . . . . . . . . . . . . 30
12.1. Construction of the Inclusive Multicast Ethernet Tag 12.1. Construction of the Inclusive Multicast Ethernet Tag
Route . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Route . . . . . . . . . . . . . . . . . . . . . . . . . . 31
12.2. P-Tunnel Identification . . . . . . . . . . . . . . . . . 30 12.2. P-Tunnel Identification . . . . . . . . . . . . . . . . . 31
13. Processing of Unknown Unicast Packets . . . . . . . . . . . . 31 13. Processing of Unknown Unicast Packets . . . . . . . . . . . . 32
13.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 32 13.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 33
13.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . . . . . 32 13.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . . . . . 33
14. Forwarding Unicast Packets . . . . . . . . . . . . . . . . . . 32 14. Forwarding Unicast Packets . . . . . . . . . . . . . . . . . . 34
14.1. Forwarding packets received from a CE . . . . . . . . . . 32 14.1. Forwarding packets received from a CE . . . . . . . . . . 34
14.2. Forwarding packets received from a remote PE . . . . . . . 34 14.2. Forwarding packets received from a remote PE . . . . . . . 35
14.2.1. Unknown Unicast Forwarding . . . . . . . . . . . . . . 34 14.2.1. Unknown Unicast Forwarding . . . . . . . . . . . . . . 35
14.2.2. Known Unicast Forwarding . . . . . . . . . . . . . . . 34 14.2.2. Known Unicast Forwarding . . . . . . . . . . . . . . . 35
15. Load Balancing of Unicast Frames . . . . . . . . . . . . . . . 34 15. Load Balancing of Unicast Frames . . . . . . . . . . . . . . . 36
15.1. Load balancing of traffic from an PE to remote CEs . . . . 34 15.1. Load balancing of traffic from an PE to remote CEs . . . . 36
15.1.1 Single-Active Redundancy Mode . . . . . . . . . . . . . 34 15.1.1 Single-Active Redundancy Mode . . . . . . . . . . . . . 36
15.1.2 All-Active Redundancy Mode . . . . . . . . . . . . . . 35 15.1.2 All-Active Redundancy Mode . . . . . . . . . . . . . . 37
15.2. Load balancing of traffic between an PE and a local CE . . 37 15.2. Load balancing of traffic between an PE and a local CE . . 38
15.2.1. Data plane learning . . . . . . . . . . . . . . . . . 37 15.2.1. Data plane learning . . . . . . . . . . . . . . . . . 38
15.2.2. Control plane learning . . . . . . . . . . . . . . . . 37 15.2.2. Control plane learning . . . . . . . . . . . . . . . . 39
16. MAC Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 37 16. MAC Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 39
16.1. MAC Duplication Issue . . . . . . . . . . . . . . . . . . 39 16.1. MAC Duplication Issue . . . . . . . . . . . . . . . . . . 41
17. Multicast . . . . . . . . . . . . . . . . . . . . . . . . . . 39 16.2. Sticky MAC addresses . . . . . . . . . . . . . . . . . . . 41
17.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 40 17. Multicast & Broadcast . . . . . . . . . . . . . . . . . . . . 41
17.2. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 40 17.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 41
17.3. MP2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 40 17.2. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 42
17.3.1. Inclusive Trees . . . . . . . . . . . . . . . . . . . 40 17.2.1. Inclusive Trees . . . . . . . . . . . . . . . . . . . 42
17.3.2. Selective Trees . . . . . . . . . . . . . . . . . . . 41
17.4. Explicit Tracking . . . . . . . . . . . . . . . . . . . . 42
18. Convergence . . . . . . . . . . . . . . . . . . . . . . . . . 42 18. Convergence . . . . . . . . . . . . . . . . . . . . . . . . . 42
18.1. Transit Link and Node Failures between PEs . . . . . . . . 42 18.1. Transit Link and Node Failures between PEs . . . . . . . . 42
18.2. PE Failures . . . . . . . . . . . . . . . . . . . . . . . 42 18.2. PE Failures . . . . . . . . . . . . . . . . . . . . . . . 43
18.2.1. Local Repair . . . . . . . . . . . . . . . . . . . . . 42 18.2. PE to CE Network Failures . . . . . . . . . . . . . . . . 43
18.3. PE to CE Network Failures . . . . . . . . . . . . . . . . 42 19. Frame Ordering . . . . . . . . . . . . . . . . . . . . . . . . 43
19. LACP State Synchronization . . . . . . . . . . . . . . . . . . 43
20. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 44 20. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 44
21. Security Considerations . . . . . . . . . . . . . . . . . . . 44 21. Security Considerations . . . . . . . . . . . . . . . . . . . 44
22. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44 22. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44
23. References . . . . . . . . . . . . . . . . . . . . . . . . . . 44 23. References . . . . . . . . . . . . . . . . . . . . . . . . . . 45
23.1 Normative References . . . . . . . . . . . . . . . . . . . 44 23.1 Normative References . . . . . . . . . . . . . . . . . . . 45
23.2 Informative References . . . . . . . . . . . . . . . . . . 45 23.2 Informative References . . . . . . . . . . . . . . . . . . 45
24. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 45 24. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 45
1. Specification of requirements 1. Specification of requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Contributors 2. Terminology
In addition to the authors listed above, the following individuals
also contributed to this document:
Quaizar Vohra
Kireeti Kompella
Apurva Mehta
Nadeem Mohammad
Juniper Networks
Clarence Filsfils
Dennis Cai
Cisco
3. Introduction
This document describes procedures for BGP MPLS based Ethernet VPNs
(E-VPN). The procedures described here are intended to meet the
requirements specified in [EVPN-REQ]. Please refer to [EVPN-REQ] for
the detailed requirements and motivation. E-VPN requires extensions
to existing IP/MPLS protocols as described in this document. In
addition to these extensions E-VPN uses several building blocks from
existing MPLS technologies.
4. Terminology Bridge Domain:
All-Active Mode: When a device is multi-homed to two or more PEs and Broadcast Domain:
when all PEs in such redundancy group can forward traffic to/from the
multi-homed device for a given VLAN, then such multi-homing or
redundancy is referred to as "All-Active".
CE: Customer Edge device e.g., host or router or switch CE: Customer Edge device e.g., host or router or switch
E-VPN Instance (EVI): An E-VPN routing and forwarding instance on a EVI: An EVPN instance spanning across the PEs participating in that
PE. VPN
Ethernet segment identifier (ESI): If a CE is multi-homed to two or MAC-VRF: A Virtual Routing and Forwarding table for MAC addresses on
a PE for an EVI
Ethernet Segment Identifier (ESI): If a CE is multi-homed to two or
more PEs, the set of Ethernet links that attaches the CE to the PEs more PEs, the set of Ethernet links that attaches the CE to the PEs
is an 'Ethernet segment'. Ethernet segments MUST have a unique non- is an 'Ethernet segment'. Ethernet segments MUST have a unique non-
zero identifier, the 'Ethernet Segment Identifier'. zero identifier, the 'Ethernet Segment Identifier'.
Ethernet Tag: An Ethernet Tag identifies a particular broadcast Ethernet Tag: An Ethernet Tag identifies a particular broadcast
domain, e.g., a VLAN. An E-VPN instance consists of one or more domain, e.g., a VLAN. An EVPN instance consists of one or more
broadcast domains. Ethernet tag(s) are assigned to the broadcast broadcast domains. Ethernet tag(s) are assigned to the broadcast
domains of a given E-VPN instance by the provider of that E-VPN, and domains of a given EVPN instance by the provider of that EVPN, and
each PE in that E-VPN instance performs a mapping between broadcast each PE in that EVPN instance performs a mapping between broadcast
domain identifier(s) understood by each of its attached CEs and the domain identifier(s) understood by each of its attached CEs and the
corresponding Ethernet tag. corresponding Ethernet tag.
Link Aggregation Control Protocol (LACP): LACP: Link Aggregation Control Protocol
Multipoint to Multipoint (MP2MP): MP2MP: Multipoint to Multipoint
Point to Multipoint (P2MP): P2MP: Point to Multipoint
Point to Point (P2P): P2P: Point to Point
Single-Active Mode: When a device or a network is multi-homed to two Single-Active Mode: When a device or a network is multi-homed to two
or more PEs and when only a single PE in such redundancy group can or more PEs and when only a single PE in such redundancy group can
forward traffic to/from the multi-homed device or network for a given forward traffic to/from the multi-homed device or network for a given
VLAN, then such multi-homing or redundancy is referred to as "Single- VLAN, then such multi-homing or redundancy is referred to as "Single-
Active". Active".
5. BGP MPLS Based E-VPN Overview All-Active Mode: When a device is multi-homed to two or more PEs and
when all PEs in such redundancy group can forward traffic to/from the
multi-homed device for a given VLAN, then such multi-homing or
redundancy is referred to as "All-Active".
This section provides an overview of E-VPN. 3. Introduction
An E-VPN comprises CEs that are connected to PEs that form the edge This document describes procedures for BGP MPLS based Ethernet VPNs
of the MPLS infrastructure. A CE may be a host, a router or a switch. (EVPN). The procedures described here are intended to meet the
The PEs provide virtual Layer 2 bridged connectivity between the CEs. requirements specified in [EVPN-REQ]. Please refer to [EVPN-REQ] for
There may be multiple E-VPNs in the provider's network. the detailed requirements and motivation. EVPN requires extensions to
existing IP/MPLS protocols as described in this document. In addition
to these extensions EVPN uses several building blocks from existing
MPLS technologies.
4. Contributors
In addition to the authors listed above, the following individuals
also contributed to this document:
Quaizar Vohra
Kireeti Kompella
Apurva Mehta
Nadeem Mohammad
Juniper Networks
Clarence Filsfils
Dennis Cai
Cisco
5. BGP MPLS Based EVPN Overview
This section provides an overview of EVPN. An EVPN instance comprises
CEs that are connected to PEs that form the edge of the MPLS
infrastructure. A CE may be a host, a router or a switch. The PEs
provide virtual Layer 2 bridged connectivity between the CEs. There
may be multiple EVPN instances in the provider's network.
The PEs may be connected by an MPLS LSP infrastructure which provides The PEs may be connected by an MPLS LSP infrastructure which provides
the benefits of MPLS technology such as fast-reroute, resiliency, the benefits of MPLS technology such as fast-reroute, resiliency,
etc. The PEs may also be connected by an IP infrastructure in which etc. The PEs may also be connected by an IP infrastructure in which
case IP/GRE tunneling or other IP tunneling can be used between the case IP/GRE tunneling or other IP tunneling can be used between the
PEs. The detailed procedures in this version of this document are PEs. The detailed procedures in this version of this document are
specified only for MPLS LSPs as the tunneling technology. However specified only for MPLS LSPs as the tunneling technology. However
these procedures are designed to be extensible to IP tunneling as the these procedures are designed to be extensible to IP tunneling as the
PSN tunneling technology. PSN tunneling technology.
In an E-VPN, MAC learning between PEs occurs not in the data plane In an EVPN, MAC learning between PEs occurs not in the data plane (as
(as happens with traditional bridging) but in the control plane. happens with traditional bridging) but in the control plane. Control
Control plane learning offers greater control over the MAC learning plane learning offers greater control over the MAC learning process,
process, such as restricting who learns what, and the ability to such as restricting who learns what, and the ability to apply
apply policies. Furthermore, the control plane chosen for policies. Furthermore, the control plane chosen for advertising MAC
advertising MAC reachability information is multi-protocol (MP) BGP reachability information is multi-protocol (MP) BGP (similar to IP
(similar to IP VPNs (RFC 4364)). This provides greater scalability VPNs (RFC 4364)). This provides greater scalability and the ability
and the ability to preserve the "virtualization" or isolation of to preserve the "virtualization" or isolation of groups of
groups of interacting agents (hosts, servers, virtual machines) from interacting agents (hosts, servers, virtual machines) from each
each other. In E-VPN, PEs advertise the MAC addresses learned from other. In EVPN, PEs advertise the MAC addresses learned from the CEs
the CEs that are connected to them, along with an MPLS label, to that are connected to them, along with an MPLS label, to other PEs in
other PEs in the control plane using MP-BGP. Control plane learning the control plane using MP-BGP. Control plane learning enables load
enables load balancing of traffic to and from CEs that are multi- balancing of traffic to and from CEs that are multi-homed to multiple
homed to multiple PEs. This is in addition to load balancing across PEs. This is in addition to load balancing across the MPLS core via
the MPLS core via multiple LSPs between the same pair of PEs. In multiple LSPs between the same pair of PEs. In other words it allows
other words it allows CEs to connect to multiple active points of CEs to connect to multiple active points of attachment. It also
attachment. It also improves convergence times in the event of improves convergence times in the event of certain network failures.
certain network failures.
However, learning between PEs and CEs is done by the method best However, learning between PEs and CEs is done by the method best
suited to the CE: data plane learning, IEEE 802.1x, LLDP, 802.1aq, suited to the CE: data plane learning, IEEE 802.1x, LLDP, 802.1aq,
ARP, management plane or other protocols. ARP, management plane or other protocols.
It is a local decision as to whether the Layer 2 forwarding table on It is a local decision as to whether the Layer 2 forwarding table on
an PE is populated with all the MAC destination addresses known to an PE is populated with all the MAC destination addresses known to
the control plane, or whether the PE implements a cache based scheme. the control plane, or whether the PE implements a cache based scheme.
For instance the MAC forwarding table may be populated only with the For instance the MAC forwarding table may be populated only with the
MAC destinations of the active flows transiting a specific PE. MAC destinations of the active flows transiting a specific PE.
The policy attributes of E-VPN are very similar to those of IP-VPN. The policy attributes of EVPN are very similar to those of IP-VPN. A
An EVI requires a Route-Distinguisher (RD) and one or more Route- EVPN instance requires a Route-Distinguisher (RD) which is unique per
Targets (RTs). A CE attaches to an E-VPN instance (EVI) on an PE, on PE and one or more globally unique Route-Targets (RTs). A CE attaches
an Ethernet interface which may be configured for one or more to a MAC-VRF on an PE, on an Ethernet interface which may be
Ethernet Tags, e.g., VLANs. Some deployment scenarios guarantee configured for one or more Ethernet Tags, e.g., VLAN IDs. Some
uniqueness of VLANs across E-VPNs: all points of attachment of a deployment scenarios guarantee uniqueness of VLAN IDs across EVPN
given EVI use the same VLAN, and no other EVI uses this VLAN. This instances: all points of attachment for a given EVPN instance use the
document refers to this case as a "Unique VLAN E-VPN" and describes same VLAN ID, and no other EVPN instance uses this VLAN ID. This
document refers to this case as a "Unique VLAN EVPN" and describes
simplified procedures to optimize for it. simplified procedures to optimize for it.
6. Ethernet Segment 6. Ethernet Segment
If a CE is multi-homed to two or more PEs, the set of Ethernet links If a CE is multi-homed to two or more PEs, the set of Ethernet links
constitutes an "Ethernet Segment". An Ethernet segment may appear to constitutes an "Ethernet Segment". An Ethernet segment may appear to
the CE as a Link Aggregation Group (LAG). Ethernet segments have an the CE as a Link Aggregation Group (LAG). Ethernet segments have an
identifier, called the "Ethernet Segment Identifier" (ESI) which is identifier, called the "Ethernet Segment Identifier" (ESI) which is
encoded as a ten octets integer. The following two ESI values are encoded as a ten octets integer. The following two ESI values are
reserved: reserved:
- ESI 0 denotes a single-homed CE. - ESI 0 denotes a single-homed CE.
- ESI {0xFF} (repeated 10 times) is known as MAX-ESI and is reserved. - ESI {0xFF} (repeated 10 times) is known as MAX-ESI and is reserved.
In general, an Ethernet segment MUST have a non-reserved ESI that is In general, an Ethernet segment MUST have a non-reserved ESI that is
unique network wide (e.g., across all EVPNs on all the PEs). If the unique network wide (e.g., across all EVPN instances on all the PEs).
CE(s) constituting an Ethernet Segment is (are) managed by the If the CE(s) constituting an Ethernet Segment is (are) managed by the
network operator, then ESI uniqueness should be guranteed; however, network operator, then ESI uniqueness should be guaranteed; however,
if the CE(s) is (are) not managed, then the operator MUST configure a if the CE(s) is (are) not managed, then the operator MUST configure a
network-wide unique ESI for that Ethernet Segment. This is required network-wide unique ESI for that Ethernet Segment. This is required
to enable auto-discovery of Ethernet Segments and DF election. The to enable auto-discovery of Ethernet Segments and DF election. The
ESI can be assigned using various mechanisms: ESI can be assigned using various mechanisms:
1. If IEEE 802.1AX LACP is used between the PEs and CEs, then 1. If IEEE 802.1AX LACP is used between the PEs and CEs, then
the ESI is determined from LACP by concatenating the following the ESI is determined from LACP by concatenating the following
parameters: parameters:
+ CE LACP System Identifier comprised of two octets of System + CE LACP System Identifier comprised of two octets of System
skipping to change at page 8, line 32 skipping to change at page 8, line 41
encoded in the low order two octets of the ESI. encoded in the low order two octets of the ESI.
As far as the CE is concerned, it would treat the multiple PEs As far as the CE is concerned, it would treat the multiple PEs
that it is connected to as the same switch. This allows the CE that it is connected to as the same switch. This allows the CE
to aggregate links that are attached to different PEs in the to aggregate links that are attached to different PEs in the
same bundle. same bundle.
This mechanism could be used only if it produces ESIs that satisfy This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above. the uniqueness requirement specified above.
2. If LLDP is used between the PEs and CEs that are hosts, then 2. In the case of indirectly connected hosts via a bridged LAN
the ESI is determined by LLDP. The ESI will be specified in a
following version.
This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above.
3. In the case of indirectly connected hosts via a bridged LAN
between the CEs and the PEs, the ESI is determined based on the between the CEs and the PEs, the ESI is determined based on the
Layer 2 bridge protocol as follows: If MST is used in the bridged Layer 2 bridge protocol as follows: If MST is used in the bridged
LAN then the value of the ESI is derived by listening to BPDUs on LAN then the value of the ESI is derived by listening to BPDUs on
the Ethernet segment. To achieve this the PE is not required to the Ethernet segment. To achieve this the PE is not required to
run MST. However the PE must learn the Root Bridge MAC address run MST. However the PE must learn the Root Bridge MAC address
and Bridge Priority of the root of the Internal Spanning Tree and Bridge Priority of the root of the Internal Spanning Tree
(IST) by listening to the BPDUs. The ESI is constructed as (IST) by listening to the BPDUs. The ESI is constructed as
follows: follows:
{Bridge Priority (16 bits) , Root Bridge MAC Address (48 bits)} {Bridge Priority (16 bits) , Root Bridge MAC Address (48 bits)}
skipping to change at page 8, line 50 skipping to change at page 9, line 4
between the CEs and the PEs, the ESI is determined based on the between the CEs and the PEs, the ESI is determined based on the
Layer 2 bridge protocol as follows: If MST is used in the bridged Layer 2 bridge protocol as follows: If MST is used in the bridged
LAN then the value of the ESI is derived by listening to BPDUs on LAN then the value of the ESI is derived by listening to BPDUs on
the Ethernet segment. To achieve this the PE is not required to the Ethernet segment. To achieve this the PE is not required to
run MST. However the PE must learn the Root Bridge MAC address run MST. However the PE must learn the Root Bridge MAC address
and Bridge Priority of the root of the Internal Spanning Tree and Bridge Priority of the root of the Internal Spanning Tree
(IST) by listening to the BPDUs. The ESI is constructed as (IST) by listening to the BPDUs. The ESI is constructed as
follows: follows:
{Bridge Priority (16 bits) , Root Bridge MAC Address (48 bits)} {Bridge Priority (16 bits) , Root Bridge MAC Address (48 bits)}
This mechanism could be used only if it produces ESIs that satisfy This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above. the uniqueness requirement specified above.
4. The ESI may be configured. 3. The ESI may be configured.
7. Ethernet Tag 7. Ethernet Tag
An Ethernet Tag identifies a particular broadcast domain, e.g. a An Ethernet Tag identifies a particular broadcast domain, e.g. a
VLAN, in an EVI. An EVI consists of one or more broadcast domains. VLAN, in an EVPN Instance. An EVPN Instance consists of one or more
Ethernet Tags are assigned to the broadcast domains of a given EVI by broadcast domains (one or more VLANs). VLANs are assigned to a given
the provider of the E-VPN service. Each PE, in a given EVI, performs EVPN Instance by the provider of the EVPN service. A given VLAN can
a mapping between the Ethernet Tag and the corresponding broadcast itself be represented by multiple VLAN IDs (VIDs). In such cases, the
domain identifier(s) understood by each of its attached CEs (e.g. CE PEs participating in that VLAN for a given EVPN instance are
VLAN Identifiers or CE-VIDs). responsible for performing VLAN ID translation to/from locally
attached CE devices.
If the broadcast domain identifiers(s) are understood consistently by
all of the CEs in an EVI, the broadcast domain identifier(s) MAY be
used as the corresponding Ethernet Tag(s). In other words, the
Ethernet Tag ID assigned by the provider is numerically equal to the
broadcast domain identifier (e.g., CE-VID = Ethernet Tag).
Further, some deployment scenarios guarantee uniqueness of broadcast If a VLAN is represented by a single VID across all PE devices
domain identifiers across all EVIs; all points of attachment of a participating in that VLAN for that EVPN instance, then there is no
given EVI use the same broadcast domain identifier(s) and no other need for VID translation at the PEs. Furthermore, some deployment
EVI uses these broadcast domain identifier(s). This allows the RT(s) scenarios guarantee uniqueness of VIDs across all EVPN instances;
for each EVI to be derived automatically, as described in section all points of attachment for a given EVPN instance use the same VID
9.4.1.1.1 "Auto-Derivation from the Ethernet Tag ID". and no other EVPN instances use that VID. This allows the RT(s) for
each EVPN instance to be derived automatically from the corresponding
VID, as described in section 9.4.1.1.1 "Auto-Derivation from the
Ethernet Tag ID".
The following subsections discuss the relationship between Ethernet The following subsections discuss the relationship between broadcast
Tags, EVIs and broadcast domain identifiers as well as the setting of domains (e.g., VLANs), Ethernet Tags (e.g., VIDs), and MAC-VRFs as
the Ethernet Tag Identifier, in the various E-VPN BGP routes (defined well as the setting of the Ethernet Tag Identifier, in the various
in section 8), for the different types of service interfaces EVPN BGP routes (defined in section 8), for the different types of
described in [EVPN-REQ]. service interfaces described in [EVPN-REQ].
7.1 VLAN Based Service Interface 7.1 VLAN Based Service Interface
With this service interface, there is a one-to-one mapping between With this service interface, an EVPN instance consists of only a
the broadcast domain identifier understood by a CE on a port (e.g. single broadcast domain (e.g., a single VLAN). Therefore, there is a
CE-VID) and an EVI. Furthermore, there is a single bridge domain per one to one mapping between a VID on this interface and a MAC-VRF.
PE for the EVI. Different CEs connected to different PE ports MAY use Since a MAC-VRF corresponds to a single VLAN, it consists of a single
different broadcast domain identifiers (e.g. CE-VIDs) for the same bridge domain corresponding to that VLAN. If the VLAN is represented
EVI. If said identifiers are different, the frames SHOULD remain by different VIDs on different PEs, then each PE needs to perform VID
tagged with the originating CE's broadcast domain identifier (e.g. translation for frames destined to its attached CEs. In such
CE-VID). When the CE broadcast domain identifiers are not consistent, scenarios, the Ethernet frames transported over MPLS/IP network
a tag translation function MUST be supported in the data path and SHOULD remain tagged with the originating VID and a VID translation
MUST be performed on the disposition PE. The Ethernet Tag Identifier MUST be supported in the data path and MUST be performed on the
in all E-VPN routes MUST be set to 0. disposition PE. The Ethernet Tag Identifier in all EVPN routes MUST
be set to 0.
7.2 VLAN Bundle Service Interface 7.2 VLAN Bundle Service Interface
With this service interface, there is a many-to-one mapping between With this service interface, an EVPN instance corresponds to several
the broadcast domain identifier understood by a CE on a port (e.g. broadcast domains (e.g., several VLANs); however, only a single
CE-VID) and an EVI. Furthermore, there is a single bridge domain per bridge domain is maintained per MAC-VRF which means multiple VLANs
PE for the EVI. Different CEs connected to different PE ports MUST share the same bridge domain. This implies MAC addresses MUST be
use the same broadcast domain identifiers (e.g. CE-VIDs) for the same unique across different VLANs for this service to work. In other
EVI. The MPLS encapsulated frames MUST remain tagged with the words, there is a many-to-one mapping between VLANs and a MAC-VRF,
originating CE's broadcast domain identifier (e.g. CE-VID). Tag and the MAC-VRF consists of a single bridge domain. Furthermore, a
translation is NOT permitted. The Ethernet Tag Identifier in all E- single VLAN must be represented by a single VID - e.g., no VID
VPN routes MUST be set to 0. translation is allowed for this service interface type. The MPLS
encapsulated frames MUST remain tagged with the originating VID. Tag
translation is NOT permitted. The Ethernet Tag Identifier in all EVPN
routes MUST be set to 0.
7.2.1 Port Based Service Interface 7.2.1 Port Based Service Interface
This service interface is a special case of the VLAN Bundle service This service interface is a special case of the VLAN Bundle service
interface, where all of the VLANs on the port are part of the same interface, where all of the VLANs on the port are part of the same
service and map to the same bundle. The procedures are identical to service and map to the same bundle. The procedures are identical to
those described in section 7.2. those described in section 7.2.
7.3 VLAN Aware Bundle Service Interface 7.3 VLAN Aware Bundle Service Interface
With this service interface, there is a many-to-one mapping between With this service interface, an EVPN instance consists of several
the broadcast domain identifier understood by a CE on a port (e.g. broadcast domains (e.g., several VLANs) with each VLAN having its own
CE-VID) and an EVI. Furthermore, there are multiple bridge domains bridge domain - e.g., multiple bridge domains (one per VLAN) is
per PE for the EVI: one broadcast domain per CE broadcast domain maintained by a single MAC-VRF corresponding to the EVPN instance. In
identifier. In the case where the CE broadcast domain identifiers are the case where a single VLAN is represented by different VIDs on
not consistent for different CEs, a normalized Ethernet Tag MUST be different CEs and thus tag (VID) translation is required, a
carried in the MPLS encapsulated frames and a tag translation normalized Ethernet Tag (VID) MUST be carried in the MPLS
function MUST be supported in the data path. This translation MUST be encapsulated frames and a tag translation function MUST be supported
performed on both the imposition as well as the disposition PEs. The in the data path. This translation MUST be performed in data path on
Ethernet Tag Identifier in all E-VPN routes MUST be set to the both the imposition as well as the disposition PEs (translating to
normalized Ethernet Tag assigned by the E-VPN provider. normalized tag on imposition PE and translating to local tag on
disposition PE). The Ethernet Tag Identifier in all EVPN routes MUST
be set to the normalized Ethernet Tag assigned by the EVPN provider.
7.3.1 Port Based VLAN Aware Service Interface 7.3.1 Port Based VLAN Aware Service Interface
This service interface is a special case of the VLAN Aware Bundle This service interface is a special case of the VLAN Aware Bundle
service interface, where all of the VLANs on the port are part of the service interface, where all of the VLANs on the port are part of the
same service and map to the same bundle. The procedures are identical same service and map to the same bundle. The procedures are identical
to those described in section 7.3. to those described in section 7.3.
8. BGP E-VPN NLRI 8. BGP EVPN NLRI
This document defines a new BGP NLRI, called the E-VPN NLRI. This document defines a new BGP NLRI, called the EVPN NLRI.
Following is the format of the E-VPN NLRI: Following is the format of the EVPN NLRI:
+-----------------------------------+ +-----------------------------------+
| Route Type (1 octet) | | Route Type (1 octet) |
+-----------------------------------+ +-----------------------------------+
| Length (1 octet) | | Length (1 octet) |
+-----------------------------------+ +-----------------------------------+
| Route Type specific (variable) | | Route Type specific (variable) |
+-----------------------------------+ +-----------------------------------+
The Route Type field defines encoding of the rest of the E-VPN NLRI The Route Type field defines encoding of the rest of the EVPN NLRI
(Route Type specific E-VPN NLRI). (Route Type specific EVPN NLRI).
The Length field indicates the length in octets of the Route Type The Length field indicates the length in octets of the Route Type
specific field of E-VPN NLRI. specific field of EVPN NLRI.
This document defines the following Route Types: This document defines the following Route Types:
+ 1 - Ethernet Auto-Discovery (A-D) route + 1 - Ethernet Auto-Discovery (A-D) route
+ 2 - MAC advertisement route + 2 - MAC advertisement route
+ 3 - Inclusive Multicast Route + 3 - Inclusive Multicast Route
+ 4 - Ethernet Segment Route + 4 - Ethernet Segment Route
The detailed encoding and procedures for these route types are The detailed encoding and procedures for these route types are
described in subsequent sections. described in subsequent sections.
The E-VPN NLRI is carried in BGP [RFC4271] using BGP Multiprotocol The EVPN NLRI is carried in BGP [RFC4271] using BGP Multiprotocol
Extensions [RFC4760] with an AFI of 25 (L2VPN) and a SAFI of 70 (E- Extensions [RFC4760] with an AFI of 25 (L2VPN) and a SAFI of 70
VPN). The NLRI field in the MP_REACH_NLRI/MP_UNREACH_NLRI attribute (EVPN). The NLRI field in the MP_REACH_NLRI/MP_UNREACH_NLRI attribute
contains the E-VPN NLRI (encoded as specified above). contains the EVPN NLRI (encoded as specified above).
In order for two BGP speakers to exchange labeled E-VPN NLRI, they In order for two BGP speakers to exchange labeled EVPN NLRI, they
must use BGP Capabilities Advertisement to ensure that they both are must use BGP Capabilities Advertisement to ensure that they both are
capable of properly processing such NLRI. This is done as specified capable of properly processing such NLRI. This is done as specified
in [RFC4760], by using capability code 1 (multiprotocol BGP) with an in [RFC4760], by using capability code 1 (multiprotocol BGP) with an
AFI of 25 (L2VPN) and a SAFI of 70 (E-VPN). AFI of 25 (L2VPN) and a SAFI of 70 (EVPN).
8.1. Ethernet Auto-Discovery Route 8.1. Ethernet Auto-Discovery Route
A Ethernet A-D route type specific E-VPN NLRI consists of the A Ethernet A-D route type specific EVPN NLRI consists of the
following: following:
+---------------------------------------+ +---------------------------------------+
| RD (8 octets) | | RD (8 octets) |
+---------------------------------------+ +---------------------------------------+
|Ethernet Segment Identifier (10 octets)| |Ethernet Segment Identifier (10 octets)|
+---------------------------------------+ +---------------------------------------+
| Ethernet Tag ID (4 octets) | | Ethernet Tag ID (4 octets) |
+---------------------------------------+ +---------------------------------------+
| MPLS Label (3 octets) | | MPLS Label (3 octets) |
+---------------------------------------+ +---------------------------------------+
For procedures and usage of this route please see section 9.2 "Fast For procedures and usage of this route please see section 9.2 "Fast
Convergence" and section 9.4 "Aliasing". Convergence" and section 9.4 "Aliasing".
8.2. MAC Advertisement Route 8.2. MAC Advertisement Route
A MAC advertisement route type specific E-VPN NLRI consists of the A MAC advertisement route type specific EVPN NLRI consists of the
following: following:
+---------------------------------------+ +---------------------------------------+
| RD (8 octets) | | RD (8 octets) |
+---------------------------------------+ +---------------------------------------+
|Ethernet Segment Identifier (10 octets)| |Ethernet Segment Identifier (10 octets)|
+---------------------------------------+ +---------------------------------------+
| Ethernet Tag ID (4 octets) | | Ethernet Tag ID (4 octets) |
+---------------------------------------+ +---------------------------------------+
| MAC Address Length (1 octet) | | MAC Address Length (1 octet) |
skipping to change at page 13, line 4 skipping to change at page 13, line 4
ID, MAC Address Length, MAC Address, IP Address Length, and IP ID, MAC Address Length, MAC Address, IP Address Length, and IP
Address Address fields are considered to be part of the prefix in the Address Address fields are considered to be part of the prefix in the
NLRI. The Ethernet Segment Identifier and MPLS Label fields are to be NLRI. The Ethernet Segment Identifier and MPLS Label fields are to be
treated as route attributes as opposed to being part of the "route". treated as route attributes as opposed to being part of the "route".
For procedures and usage of this route please see section 10 For procedures and usage of this route please see section 10
"Determining Reachability to Unicast MAC Addresses" and section 15 "Determining Reachability to Unicast MAC Addresses" and section 15
"Load Balancing of Unicast Packets". "Load Balancing of Unicast Packets".
8.3. Inclusive Multicast Ethernet Tag Route 8.3. Inclusive Multicast Ethernet Tag Route
An Inclusive Multicast Ethernet Tag route type specific E-VPN NLRI An Inclusive Multicast Ethernet Tag route type specific EVPN NLRI
consists of the following: consists of the following:
+---------------------------------------+ +---------------------------------------+
| RD (8 octets) | | RD (8 octets) |
+---------------------------------------+ +---------------------------------------+
| Ethernet Tag ID (4 octets) | | Ethernet Tag ID (4 octets) |
+---------------------------------------+ +---------------------------------------+
| IP Address Length (1 octet) | | IP Address Length (1 octet) |
+---------------------------------------+ +---------------------------------------+
| Originating Router's IP Addr | | Originating Router's IP Addr |
| (4 or 16 octets) | | (4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
For procedures and usage of this route please see section 12 For procedures and usage of this route please see section 12
"Handling of Multi-Destination Traffic", section 13 "Processing of "Handling of Multi-Destination Traffic", section 13 "Processing of
Unknown Unicast Traffic" and section 17 "Multicast". Unknown Unicast Traffic" and section 17 "Multicast".
8.4 Ethernet Segment Route 8.4 Ethernet Segment Route
The Ethernet Segment Route is encoded in the E-VPN NLRI using the The Ethernet Segment Route is encoded in the EVPN NLRI using the
Route Type value of 4. The Route Type Specific field of the NLRI is Route Type value of 4. The Route Type Specific field of the NLRI is
formatted as follows: formatted as follows:
+---------------------------------------+ +---------------------------------------+
| RD (8 octets) | | RD (8 octets) |
+---------------------------------------+ +---------------------------------------+
|Ethernet Segment Identifier (10 octets)| |Ethernet Segment Identifier (10 octets)|
+---------------------------------------+ +---------------------------------------+
| IP Address Length (1 octet) |
+---------------------------------------+
| Originating Router's IP Addr |
| (4 or 16 octets) |
+---------------------------------------+
For procedures and usage of this route please see section 9.5 For procedures and usage of this route please see section 9.5
"Designated Forwarder Election". "Designated Forwarder Election".
8.5 ESI Label Extended Community 8.5 ESI Label Extended Community
This extended community is a new transitive extended community with This extended community is a new transitive extended community with
the Type field is 0x06, and the Sub-Type of 0x01. It may be the Type field is 0x06, and the Sub-Type of 0x01. It may be
advertised along with Ethernet Auto-Discovery routes and it enables advertised along with Ethernet Auto-Discovery routes and it enables
split-horizon procedures for multi-homed sites as described in split-horizon procedures for multi-homed sites as described in
skipping to change at page 15, line 14 skipping to change at page 15, line 14
This extended community is a new transitive extended community with This extended community is a new transitive extended community with
the Type field of 0x06 and the Sub-Type of 0x00. It may be advertised the Type field of 0x06 and the Sub-Type of 0x00. It may be advertised
along with MAC Advertisement routes. The procedures for using this along with MAC Advertisement routes. The procedures for using this
Extended Community are described in section 16 "MAC Mobility". Extended Community are described in section 16 "MAC Mobility".
The MAC Mobility Extended Community is encoded as a 8-octet value as The MAC Mobility Extended Community is encoded as a 8-octet value as
follows: follows:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x06 | Sub-Type=0x00 | Reserved=0 | | Type=0x06 | Sub-Type=0x00 |Flags(1 octet)| Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number | | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The low order bit of the flags octet is defined as the
"Sticky/static" flag and may be set to 1. A value of 1 means that the
MAC address is static and cannot move.
8.8 Default Gateway Extended Community 8.8 Default Gateway Extended Community
The Default Gateway community is an Extended Community of an Opaque The Default Gateway community is an Extended Community of an Opaque
Type (see 3.3 of rfc4360). It is a transitive community, which means Type (see 3.3 of rfc4360). It is a transitive community, which means
that the first octet is 0x03. The value of the second octet (Sub- that the first octet is 0x03. The value of the second octet (Sub-
Type) is 0x030d (Default Gateway) as defined by IANA. The Value field Type) is 0x030d (Default Gateway) as defined by IANA. The Value field
of this community is reserved (set to 0 by the senders, ignored by of this community is reserved (set to 0 by the senders, ignored by
the receivers). the receivers).
9. Multi-homing Functions 9. Multi-homing Functions
This section discusses the functions, procedures and associated BGP This section discusses the functions, procedures and associated BGP
routes used to support multi-homing in E-VPN. This covers both multi- routes used to support multi-homing in EVPN. This covers both multi-
homed device (MHD) as well as multi-homed network (MHN) scenarios. homed device (MHD) as well as multi-homed network (MHN) scenarios.
9.1 Multi-homed Ethernet Segment Auto-Discovery 9.1 Multi-homed Ethernet Segment Auto-Discovery
PEs connected to the same Ethernet segment can automatically discover PEs connected to the same Ethernet segment can automatically discover
each other with minimal to no configuration through the exchange of each other with minimal to no configuration through the exchange of
the Ethernet Segment route. the Ethernet Segment route.
9.1.1 Constructing the Ethernet Segment Route 9.1.1 Constructing the Ethernet Segment Route
skipping to change at page 16, line 13 skipping to change at page 16, line 19
also carry an ES-Import extended community attribute, as defined in also carry an ES-Import extended community attribute, as defined in
section 8.6. section 8.6.
The Ethernet Segment Route filtering MUST be done such that the The Ethernet Segment Route filtering MUST be done such that the
Ethernet Segment Route is imported only by the PEs that are multi- Ethernet Segment Route is imported only by the PEs that are multi-
homed to the same Ethernet Segment. To that end, each PE that is homed to the same Ethernet Segment. To that end, each PE that is
connected to a particular Ethernet segment constructs an import connected to a particular Ethernet segment constructs an import
filtering rule to import a route that carries the ES-Import extended filtering rule to import a route that carries the ES-Import extended
community, constructed from the ESI. community, constructed from the ESI.
Note that the new ES-Import extended community is not the same as the
Route Target Extended Community. The Ethernet Segment route carries
this new ES-Import extended community. The PEs apply filtering on
this new extended community. As a result the Ethernet Segment route
is imported only by the PEs that are connected to the same Ethernet
segment.
9.2 Fast Convergence 9.2 Fast Convergence
In E-VPN, MAC address reachability is learnt via the BGP control- In EVPN, MAC address reachability is learnt via the BGP control-plane
plane over the MPLS network. As such, in the absence of any fast over the MPLS network. As such, in the absence of any fast protection
protection mechanism, the network convergence time is a function of mechanism, the network convergence time is a function of the number
the number of MAC Advertisement routes that must be withdrawn by the of MAC Advertisement routes that must be withdrawn by the PE
PE encountering a failure. For highly scaled environments, this encountering a failure. For highly scaled environments, this scheme
scheme yields slow convergence. yields slow convergence.
To alleviate this, E-VPN defines a mechanism to efficiently and To alleviate this, EVPN defines a mechanism to efficiently and
quickly signal, to remote PE nodes, the need to update their quickly signal, to remote PE nodes, the need to update their
forwarding tables upon the occurrence of a failure in connectivity to forwarding tables upon the occurrence of a failure in connectivity to
an Ethernet segment. This is done by having each PE advertise an an Ethernet segment. This is done by having each PE advertise an
Ethernet A-D Route per Ethernet segment for each locally attached Ethernet A-D Route per Ethernet segment for each locally attached
segment (refer to section 9.2.1 below for details on how this route segment (refer to section 9.2.1 below for details on how this route
is constructed). Upon a failure in connectivity to the attached is constructed). Upon a failure in connectivity to the attached
segment, the PE withdraws the corresponding Ethernet A-D route. This segment, the PE withdraws the corresponding Ethernet A-D route. This
triggers all PEs that receive the withdrawal to update their next-hop triggers all PEs that receive the withdrawal to update their next-hop
adjacencies for all MAC addresses associated with the Ethernet adjacencies for all MAC addresses associated with the Ethernet
segment in question. If no other PE had advertised an Ethernet A-D segment in question. If no other PE had advertised an Ethernet A-D
skipping to change at page 17, line 40 skipping to change at page 17, line 38
If the Ethernet Segment is connected to more than one PE and Single- If the Ethernet Segment is connected to more than one PE and Single-
Active multi-homing is desired, then the "Active-Standby" bit in the Active multi-homing is desired, then the "Active-Standby" bit in the
flags of the ESI Label Extended Community MUST be set to 1 and ESI flags of the ESI Label Extended Community MUST be set to 1 and ESI
label MUST be set to zero. label MUST be set to zero.
9.2.1.1. Ethernet A-D Route Targets 9.2.1.1. Ethernet A-D Route Targets
The Ethernet A-D route MUST carry one or more Route Target (RT) The Ethernet A-D route MUST carry one or more Route Target (RT)
attributes. These RTs MUST be the set of RTs associated with all the attributes. These RTs MUST be the set of RTs associated with all the
EVIs to which the Ethernet Segment, corresponding to the Ethernet A-D EVPN instances to which the Ethernet Segment, corresponding to the
route, belongs. Ethernet A-D route, belongs.
9.3 Split Horizon 9.3 Split Horizon
Consider a CE that is multi-homed to two or more PEs on an Ethernet Consider a CE that is multi-homed to two or more PEs on an Ethernet
segment ES1 operating in All-Active mode. If the CE sends a segment ES1 operating in All-Active mode. If the CE sends a
broadcast, unknown unicast, or multicast (BUM) packet to one of the broadcast, unknown unicast, or multicast (BUM) packet to one of the
non-DF (Designated Forwarder) PEs, say PE1, then PE1 will forward non-DF (Designated Forwarder) PEs, say PE1, then PE1 will forward
that packet to all or subset of the other PEs in the EVI including that packet to all or subset of the other PEs in that EVPN instance
the DF PE for that Ethernet segment. In this case the DF PE that the including the DF PE for that Ethernet segment. In this case the DF PE
CE is multi-homed to MUST drop the packet and not forward back to the that the CE is multi-homed to MUST drop the packet and not forward
CE. This filtering is referred to as "split horizon" filtering in back to the CE. This filtering is referred to as "split horizon"
this document. filtering in this document.
In order to achieve this split horizon function, every BUM packet In order to achieve this split horizon function, every BUM packet
originating from a non-DF PE is encapsulated with an MPLS label that originating from a non-DF PE is encapsulated with an MPLS label that
identifies the Ethernet segment of origin (i.e. the segment from identifies the Ethernet segment of origin (i.e. the segment from
which the frame entered the E-VPN network). This label is referred to which the frame entered the EVPN network). This label is referred to
as the ESI label, and MUST be distributed by all PEs when operating as the ESI label, and MUST be distributed by all PEs when operating
in All-Active multi-homing mode using the "Ethernet A-D route per in All-Active multi-homing mode using the "Ethernet A-D route per
Ethernet Segment" as per the procedures in section 9.2.1 above. This Ethernet Segment" as per the procedures in section 9.2.1 above. This
route is imported by the PEs connected to the Ethernet Segment and route is imported by the PEs connected to the Ethernet Segment and
also by the PEs that have at least one EVI in common with the also by the PEs that have at least one EVPN instance in common with
Ethernet Segment in the route. As described in section 9.1.1, the the Ethernet Segment in the route. As described in section 9.1.1, the
route MUST carry an ESI Label Extended Community with a valid ESI route MUST carry an ESI Label Extended Community with a valid ESI
label. The disposition DF PE rely on the value of the ESI label to label. The disposition DF PE rely on the value of the ESI label to
determine whether or not a BUM frame is allowed to egress a specific determine whether or not a BUM frame is allowed to egress a specific
Ethernet segment. It should be noted that if the BUM frame is Ethernet segment. It should be noted that if the BUM frame is
originated from the DF PE operating in All-Active multi-homing mode, originated from the DF PE operating in All-Active multi-homing mode,
then the DF PE MAY not encapsulate the frame with the ESI label. then the DF PE MAY not encapsulate the frame with the ESI label.
Furthermore, if the multi-homed PEs operate in active/standby mode, Furthermore, if the multi-homed PEs operate in active/standby mode,
then the packet MUST not be encapsulated with the ESI label and the then the packet MUST NOT be encapsulated with the ESI label and the
label value MUST be set to zero in ESI Label Extended Community per label value MUST be set to zero in ESI Label Extended Community per
section 9.2.1 above. section 9.2.1 above.
9.3.1 ESI Label Assignment 9.3.1 ESI Label Assignment
The following subsections describe the assignment procedures for the The following subsections describe the assignment procedures for the
ESI label, which differ depending on the type of tunnels being used ESI label, which differ depending on the type of tunnels being used
to deliver multi-destination packets in the E-VPN network. to deliver multi-destination packets in the EVPN network.
9.3.1.1 Ingress Replication 9.3.1.1 Ingress Replication
All PEs operating in an All-Active multi-homing mode that rely on All PEs operating in an All-Active multi-homing mode that rely on
ingress replication for the reception of BUM traffic, distribute to ingress replication for the reception of BUM traffic, distribute to
other PEs, that belong to the Ethernet segment, a downstream assigned other PEs, that belong to the Ethernet segment, a downstream assigned
"ESI label" in the Ethernet A-D route per ESI. This label MUST be "ESI label" in the Ethernet A-D route per ESI. This label MUST be
programmed in the platform label space by the advertising PE. Further programmed in the platform label space by the advertising PE. Further
the forwarding entry for this label must result in NOT forwarding the forwarding entry for this label must result in NOT forwarding
packets received with this label onto the Ethernet segment that the packets received with this label onto the Ethernet segment that the
label was distributed for. label was distributed for.
Consider PE1 and PE2 that are multi-homed to CE1 on ES1 and operating Consider PE1 and PE2 that are multi-homed to CE1 on ES1 and operating
in All-Active multi-homing mode. Further consider that PE1 is using in All-Active multi-homing mode. Further consider that PE1 is using
P2P or MP2P LSPs to send packets to PE2. Consider that PE1 is the P2P or MP2P LSPs to send packets to PE2. Consider that PE1 is the
non-DF for VLAN1 and PE2 is the DF for VLAN1, and PE1 receives a BUM non-DF for VLAN1 and PE2 is the DF for VLAN1, and PE1 receives a BUM
packet from CE1 on VLAN1 on ES1. In this scenario, PE2 distributes an packet from CE1 on VLAN1 on ES1. In this scenario, PE2 distributes an
Inclusive Multicast Ethernet Tag route for VLAN1 in the associated Inclusive Multicast Ethernet Tag route for VLAN1 corresponding to an
EVI. So, when PE1 sends a BUM packet, that it receives from CE1, it EVPN instance. So, when PE1 sends a BUM packet, that it receives from
MUST first push onto the MPLS label stack the ESI label that PE2 has CE1, it MUST first push onto the MPLS label stack the ESI label that
distributed for ES1. It MUST then push on the MPLS label distributed PE2 has distributed for ES1. It MUST then push on the MPLS label
by PE2 in the Inclusive Multicast Ethernet Tag route for VLAN1. The distributed by PE2 in the Inclusive Multicast Ethernet Tag route for
resulting packet is further encapsulated in the P2P or MP2P LSP label VLAN1. The resulting packet is further encapsulated in the P2P or
stack required to transmit the packet to PE2. When PE2 receives this MP2P LSP label stack required to transmit the packet to PE2. When
packet, it determines the set of ESIs to replicate the packet to from PE2 receives this packet, it determines the set of ESIs to replicate
the top MPLS label, after any P2P or MP2P LSP labels have been the packet to from the top MPLS label, after any P2P or MP2P LSP
removed. If the next label is the ESI label assigned by PE2 for ES1, labels have been removed. If the next label is the ESI label assigned
then PE2 MUST NOT forward the packet onto ES1. If the next label is by PE2 for ES1, then PE2 MUST NOT forward the packet onto ES1. If the
an ESI label which has not been assigned by PE2, then PE2 MUST drop next label is an ESI label which has not been assigned by PE2, then
the packet. It should be noted that in this scenario, if PE2 receives PE2 MUST drop the packet. It should be noted that in this scenario,
a BUM traffic for VLAN1 from CE1, then it doesn't need to encapsulate if PE2 receives a BUM traffic for VLAN1 from CE1, then it doesn't
the packet with an ESI label when sending it to the PE1 since PE1 can need to encapsulate the packet with an ESI label when sending it to
use its DF logic to filter the BUM packets and thus doesn't need to the PE1 since PE1 can use its DF logic to filter the BUM packets and
use split-horizon filtering for ES1. thus doesn't need to use split-horizon filtering for ES1.
9.3.1.2. P2MP MPLS LSPs 9.3.1.2. P2MP MPLS LSPs
The non-DF PEs operating in an All-Active multi-homing mode that is The non-DF PEs operating in an All-Active multi-homing mode that is
using P2MP LSPs for sending BUM traffic, distribute to other PEs, using P2MP LSPs for sending BUM traffic, distribute to other PEs,
that belong to the Ethernet segment or have an E-VPN in common with that belong to the Ethernet segment or have an EVPN instance in
the Ethernet Segment, an upstream assigned "ESI label" in the common with the Ethernet Segment, an upstream assigned "ESI label" in
Ethernet A-D route. This label is upstream assigned by the PE that the Ethernet A-D route. This label is upstream assigned by the PE
advertises the route. This label MUST be programmed by the other PEs, that advertises the route. This label MUST be programmed by the other
that are connected to the ESI advertised in the route, in the context PEs, that are connected to the ESI advertised in the route, in the
label space for the advertising PE. Further the forwarding entry for context label space for the advertising PE. Further the forwarding
this label must result in NOT forwarding packets received with this entry for this label must result in NOT forwarding packets received
label onto the Ethernet segment that the label was distributed for. with this label onto the Ethernet segment that the label was
This label MUST also be programmed by the other PEs, that import the distributed for. This label MUST also be programmed by the other PEs,
route but are not connected to the ESI advertised in the route, in that import the route but are not connected to the ESI advertised in
the context label space for the advertising PE. Further the the route, in the context label space for the advertising PE. Further
forwarding entry for this label must be a POP with no other the forwarding entry for this label must be a POP with no other
associated action. associated action.
Consider PE1 and PE2 that are multi-homed to CE1 on ES1 and operating Consider PE1 and PE2 that are multi-homed to CE1 on ES1 and operating
in All-Active multi-homing mode. Also consider PE3 that is in the in All-Active multi-homing mode. Also consider PE3 belongs to one of
same EVI as one of the EVIs to which ES1 belongs. Further, assume the EVPN instances of ES1. Further, assume that PE1 which is the
that PE1 which is the non-DF, using P2MP MPLS LSPs to send BUM non-DF, using P2MP MPLS LSPs to send BUM packets. When PE1 sends a
packets. When PE1 sends a BUM packet, that it receives from CE1, it BUM packet, that it receives from CE1, it MUST first push onto the
MUST first push onto the MPLS label stack the ESI label that it has MPLS label stack the ESI label that it has assigned for the ESI that
assigned for the ESI that the packet was received on. The resulting the packet was received on. The resulting packet is further
packet is further encapsulated in the P2MP MPLS label stack necessary encapsulated in the P2MP MPLS label stack necessary to transmit the
to transmit the packet to the other PEs. Penultimate hop popping MUST packet to the other PEs. Penultimate hop popping MUST be disabled on
be disabled on the P2MP LSPs used in the MPLS transport the P2MP LSPs used in the MPLS transport infrastructure for EVPN.
infrastructure for E-VPN. When PE2 receives this packet, it de- When PE2 receives this packet, it de-capsulates the top MPLS label
capsulates the top MPLS label and forwards the packet using the and forwards the packet using the context label space determined by
context label space determined by the top label. If the next label is the top label. If the next label is the ESI label assigned by PE1 to
the ESI label assigned by PE1 to ES1, then PE2 MUST NOT forward the ES1, then PE2 MUST NOT forward the packet onto ES1. When PE3 receives
packet onto ES1. When PE3 receives this packet, it de-capsulates the this packet, it de-capsulates the top MPLS label and forwards the
top MPLS label and forwards the packet using the context label space packet using the context label space determined by the top label. If
determined by the top label. If the next label is the ESI label the next label is the ESI label assigned by PE1 to ES1 and PE3 is not
assigned by PE1 to ES1 and PE3 is not connected to ES1, then PE3 MUST connected to ES1, then PE3 MUST pop the label and flood the packet
pop the label and flood the packet over all local ESIs in the EVI. It over all local ESIs in that EVPN instance. It should be noted that
should be noted that when PE2 sends a BUM frame over a P2MP LSP, it when PE2 sends a BUM frame over a P2MP LSP, it does not need to
does not need to encapsulate the frame with an ESI label because it encapsulate the frame with an ESI label because it is the DF for that
is the DF for that VLAN. VLAN.
9.3.1.3. MP2MP LSPs
The procedures for ESI Label assignment and usage for MP2MP LSPs will
be described in a future version.
9.4 Aliasing and Backup-Path 9.4 Aliasing and Backup-Path
In the case where a CE is multi-homed to multiple PE nodes, using a In the case where a CE is multi-homed to multiple PE nodes, using a
LAG with All-Active redundancy, it is possible that only a single PE LAG with All-Active redundancy, it is possible that only a single PE
learns a set of the MAC addresses associated with traffic transmitted learns a set of the MAC addresses associated with traffic transmitted
by the CE. This leads to a situation where remote PE nodes receive by the CE. This leads to a situation where remote PE nodes receive
MAC advertisement routes, for these addresses, from a single PE even MAC advertisement routes, for these addresses, from a single PE even
though multiple PEs are connected to the multi-homed segment. As a though multiple PEs are connected to the multi-homed segment. As a
result, the remote PEs are not able to effectively load-balance result, the remote PEs are not able to effectively load-balance
traffic among the PE nodes connected to the multi-homed Ethernet traffic among the PE nodes connected to the multi-homed Ethernet
segment. This could be the case, for e.g. when the PEs perform data- segment. This could be the case, for e.g. when the PEs perform data-
path learning on the access, and the load-balancing function on the path learning on the access, and the load-balancing function on the
CE hashes traffic from a given source MAC address to a single PE. CE hashes traffic from a given source MAC address to a single PE.
Another scenario where this occurs is when the PEs rely on control Another scenario where this occurs is when the PEs rely on control
plane learning on the access (e.g. using ARP), since ARP traffic will plane learning on the access (e.g. using ARP), since ARP traffic will
be hashed to a single link in the LAG. be hashed to a single link in the LAG.
To alleviate this issue, E-VPN introduces the concept of 'Aliasing'. To alleviate this issue, EVPN introduces the concept of 'Aliasing'.
Aliasing refers to the ability of a PE to signal that it has Aliasing refers to the ability of a PE to signal that it has
reachability to a given locally attached Ethernet segment, even when reachability to a given locally attached Ethernet segment, even when
it has learnt no MAC addresses from that segment. The Ethernet A-D it has learnt no MAC addresses from that segment. The Ethernet A-D
route per EVI is used to that end. Remote PEs which receive MAC route per EVI is used to that end. Remote PEs which receive MAC
advertisement routes with non-reserved ESI SHOULD consider the advertisement routes with non-reserved ESI SHOULD consider the
advertised MAC address as reachable via all PEs which have advertised advertised MAC address as reachable via all PEs which have advertised
reachability to the relevant Segment using: (1) Ethernet A-D routes reachability to the relevant Segment using: (1) Ethernet A-D routes
per EVI with the same ESI (and Ethernet Tag if applicable) AND per EVI with the same ESI (and Ethernet Tag if applicable) AND
(2)Ethernet A-D routes per ESI with the same ESI and with the (2)Ethernet A-D routes per ESI with the same ESI and with the
Active/Standby bit set to 0 in the ESI Label Extended Community. Active/Standby bit set to 0 in the ESI Label Extended Community.
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Backup-Path is a closely related function, albeit it applies to the Backup-Path is a closely related function, albeit it applies to the
case where the redundancy mode is Active/Standby. In this case, the case where the redundancy mode is Active/Standby. In this case, the
PE advertises that it has reachability to a given locally attached PE advertises that it has reachability to a given locally attached
Ethernet Segment using the Ethernet A-D route as well. Remote PEs Ethernet Segment using the Ethernet A-D route as well. Remote PEs
which receive the MAC advertisement routes, with non-reserved ESI, which receive the MAC advertisement routes, with non-reserved ESI,
MUST consider the MAC address as reachable via the advertising PE. MUST consider the MAC address as reachable via the advertising PE.
Furthermore, the remote PEs SHOULD install a Backup-Path, for said Furthermore, the remote PEs SHOULD install a Backup-Path, for said
MAC, to the PE which had advertised reachability to the relevant MAC, to the PE which had advertised reachability to the relevant
Segment using (1) an Ethernet A-D routes per EVI with the same ESI Segment using (1) an Ethernet A-D routes per EVI with the same ESI
(and Ethernet Tag if applicable) AND (2)Ethernet A-D routes per ESI (and Ethernet Tag if applicable) AND (2) Ethernet A-D routes per ESI
with the same ESI and with the Active/Standby bit set to 1 in the ESI with the same ESI and with the Active/Standby bit set to 1 in the ESI
Label Extended Community. Label Extended Community.
9.4.1 Constructing the Ethernet A-D Route per EVI 9.4.1 Constructing the Ethernet A-D Route per EVI
This section describes procedures to construct the Ethernet A-D route This section describes procedures to construct the Ethernet A-D route
when one or more such routes are advertised by an PE for a given EVI. when one or more such routes are advertised by an PE for a given EVI.
This flavor of the Ethernet A-D route is used for aliasing, and This flavor of the Ethernet A-D route is used for aliasing, and
support of this route flavor is OPTIONAL. support of this route flavor is OPTIONAL.
Route-Distinguisher (RD) MUST be set to the RD of the EVI that is Route-Distinguisher (RD) MUST be set to the RD of the EVI that is
advertising the NLRI. An RD MUST be assigned for a given EVI on an advertising the NLRI. An RD MUST be assigned for a given EVI on an
PE. This RD MUST be unique across all EVIs on an PE. It is PE. This RD MUST be unique across all EVIs on an PE. It is
RECOMMENDED to use the Type 1 RD [RFC4364]. The value field comprises RECOMMENDED to use the Type 1 RD [RFC4364]. The value field comprises
an IP address of the PE (typically, the loopback address) followed by an IP address of the PE (typically, the loopback address) followed by
a number unique to the PE. This number may be generated by the PE. a number unique to the PE. This number may be generated by the PE.
Or in the Unique VLAN E-VPN case, the low order 12 bits may be the 12 Or in the Unique VLAN EVPN case, the low order 12 bits may be the 12
bit VLAN ID, with the remaining high order 4 bits set to 0. bit VLAN ID, with the remaining high order 4 bits set to 0.
The Ethernet Segment Identifier MUST be a ten octet entity as The Ethernet Segment Identifier MUST be a ten octet entity as
described in section "Ethernet Segment Identifier". This document described in section "Ethernet Segment Identifier". This document
does not specify the use of the Ethernet A-D route when the Segment does not specify the use of the Ethernet A-D route when the Segment
Identifier is set to 0. Identifier is set to 0.
The Ethernet Tag ID is the identifier of an Ethernet Tag on the The Ethernet Tag ID is the identifier of an Ethernet Tag on the
Ethernet segment. This value may be a 12 bit VLAN ID, in which case Ethernet segment. This value may be a 12 bit VLAN ID, in which case
the low order 12 bits are set to the VLAN ID and the high order 20 the low order 12 bits are set to the VLAN ID and the high order 20
bits are set to 0. Or it may be another Ethernet Tag used by the E- bits are set to 0. Or it may be another Ethernet Tag used by the
VPN. It MAY be set to the default Ethernet Tag on the Ethernet EVPN. It MAY be set to the default Ethernet Tag on the Ethernet
segment or to the value 0. segment or to the value 0.
Note that the above allows the Ethernet A-D route to be advertised Note that the above allows the Ethernet A-D route to be advertised
with one of the following granularities: with one of the following granularities:
+ One Ethernet A-D route for a given <ESI, Ethernet Tag ID> tuple + One Ethernet A-D route for a given <ESI, Ethernet Tag ID> tuple
per EVI. This is applicable when the PE uses MPLS-based per EVI. This is applicable when the PE uses MPLS-based
disposition. disposition.
+ One Ethernet A-D route per <ESI, EVI> (where the Ethernet + One Ethernet A-D route per <ESI, EVI> (where the Ethernet
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+ The Global Administrator field of the RT MUST + The Global Administrator field of the RT MUST
be set to the Autonomous System (AS) number that the PE be set to the Autonomous System (AS) number that the PE
belongs to. belongs to.
+ The Local Administrator field of the RT contains a 4 + The Local Administrator field of the RT contains a 4
octets long number that encodes the Ethernet Tag-ID. If the octets long number that encodes the Ethernet Tag-ID. If the
Ethernet Tag-ID is a two octet VLAN ID then it MUST be Ethernet Tag-ID is a two octet VLAN ID then it MUST be
encoded in the lower two octets of the Local Administrator encoded in the lower two octets of the Local Administrator
field and the higher two octets MUST be set to zero. field and the higher two octets MUST be set to zero.
For the "Unique VLAN E-VPN" this results in auto-deriving the RT from For the "Unique VLAN EVPN" this results in auto-deriving the RT from
the Ethernet Tag, e.g., VLAN ID for that E-VPN. the Ethernet Tag, e.g., VLAN ID for that EVPN.
9.5 Designated Forwarder Election 9.5 Designated Forwarder Election
Consider a CE that is a host or a router that is multi-homed directly Consider a CE that is a host or a router that is multi-homed directly
to more than one PE in an E-VPN on a given Ethernet segment. One or to more than one PE in an EVPN instance on a given Ethernet segment.
more Ethernet Tags may be configured on the Ethernet segment. In this One or more Ethernet Tags may be configured on the Ethernet segment.
scenario only one of the PEs, referred to as the Designated Forwarder In this scenario only one of the PEs, referred to as the Designated
(DF), is responsible for certain actions: Forwarder (DF), is responsible for certain actions:
- Sending multicast and broadcast traffic, on a given Ethernet - Sending multicast and broadcast traffic, on a given Ethernet
Tag on a particular Ethernet segment, to the CE. Tag on a particular Ethernet segment, to the CE.
- Flooding unknown unicast traffic (i.e. traffic for - Flooding unknown unicast traffic (i.e. traffic for
which an PE does not know the destination MAC address), which an PE does not know the destination MAC address),
on a given Ethernet Tag on a particular Ethernet segment on a given Ethernet Tag on a particular Ethernet segment
to the CE, if the environment requires flooding of to the CE, if the environment requires flooding of
unknown unicast traffic. unknown unicast traffic.
Note that this behavior, which allows selecting a DF at the Note that this behavior, which allows selecting a DF at the
granularity of <ESI, EVI> for multicast, broadcast and unknown granularity of <ESI, EVI> for multicast, broadcast and unknown
unicast traffic, is the default behavior in this specification. unicast traffic, is the default behavior in this specification.
Optional mechanisms, which will be specified in the future, will
allow selecting a DF at the granularity of <ESI, EVI, S, G>.
Note that a CE always sends packets belonging to a specific flow Note that a CE always sends packets belonging to a specific flow
using a single link towards an PE. For instance, if the CE is a host using a single link towards an PE. For instance, if the CE is a host
then, as mentioned earlier, the host treats the multiple links that then, as mentioned earlier, the host treats the multiple links that
it uses to reach the PEs as a Link Aggregation Group (LAG). The CE it uses to reach the PEs as a Link Aggregation Group (LAG). The CE
employs a local hashing function to map traffic flows onto links in employs a local hashing function to map traffic flows onto links in
the LAG. the LAG.
If a bridged network is multi-homed to more than one PE in an E-VPN If a bridged network is multi-homed to more than one PE in an EVPN
via switches, then the support of All-Active points of attachments, network via switches, then the support of All-Active points of
as described in this specification, requires the bridge network to be attachments, as described in this specification, requires the bridge
connected to two or more PEs using a LAG. In this case the reasons network to be connected to two or more PEs using a LAG. In this case
for doing DF election are the same as those described above when a CE the reasons for doing DF election are the same as those described
is a host or a router. above when a CE is a host or a router.
If a bridged network does not connect to the PEs using LAG, then only If a bridged network does not connect to the PEs using LAG, then only
one of the links between the switched bridged network and the PEs one of the links between the switched bridged network and the PEs
must be the active link for a given Ethernet Tag. In this case, the must be the active link for a given Ethernet Tag. In this case, the
Ethernet A-D route per Ethernet segment MUST be advertised with the Ethernet A-D route per Ethernet segment MUST be advertised with the
"Active-Standby" flag set to one. Procedures for supporting All- "Active-Standby" flag set to one. Procedures for supporting All-
Active points of attachments, when a bridge network connects to the Active points of attachments, when a bridge network connects to the
PEs using LAG, are for further study. PEs using LAG, are for further study.
The default procedure for DF election at the granularity of <ESI, The default procedure for DF election at the granularity of <ESI,
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advertises an Ethernet Segment route with the associated ES-Import advertises an Ethernet Segment route with the associated ES-Import
extended community attribute. extended community attribute.
2. The PE then starts a timer (default value = 3 seconds) to allow 2. The PE then starts a timer (default value = 3 seconds) to allow
the reception of Ethernet Segment routes from other PE nodes the reception of Ethernet Segment routes from other PE nodes
connected to the same Ethernet Segment. This timer value MUST be same connected to the same Ethernet Segment. This timer value MUST be same
across all PEs connected to the same Ethernet Segment. across all PEs connected to the same Ethernet Segment.
3. When the timer expires, each PE builds an ordered list of the IP 3. When the timer expires, each PE builds an ordered list of the IP
addresses of all the PE nodes connected to the Ethernet Segment addresses of all the PE nodes connected to the Ethernet Segment
(including itself), in increasing numeric value. Every PE is then (including itself), in increasing numeric value. Each IP address in
this list is extracted from the "Originator Router's IP address"
field of the advertised Ethernet Segment route. Every PE is then
given an ordinal indicating its position in the ordered list, given an ordinal indicating its position in the ordered list,
starting with 0 as the ordinal for the PE with the numerically lowest starting with 0 as the ordinal for the PE with the numerically lowest
IP address. The ordinals are used to determine which PE node will be IP address. The ordinals are used to determine which PE node will be
the DF for a given EVI on the Ethernet Segment using the following the DF for a given EVPN instance on the Ethernet Segment using the
rule: Assuming a redundancy group of N PE nodes, the PE with ordinal following rule: Assuming a redundancy group of N PE nodes, the PE
i is the DF for an EVI with an associated Ethernet Tag value V when with ordinal i is the DF for an EVPN instance with an associated
(V mod N) = i. In the case where multiple Ethernet Tags are Ethernet Tag value V when (V mod N) = i. In the case where multiple
associated with a single EVI, then the numerically lowest Ethernet Ethernet Tags are associated with a single EVPN instance, then the
Tag value in that EVI MUST be used in the modulo function. numerically lowest Ethernet Tag value in that EVPN instance MUST be
used in the modulo function.
4. The PE that is elected as a DF for a given EVI will unblock It should be noted that using "Originator Router's IP address" field
traffic for the Ethernet Tags associated with that EVI. Note that the in the Ethernet Segment route to get the PE IP address needed for the
DF PE unblocks multi-destination traffic in the egress direction ordered list, allows for a CE to be multi-homed across different ASes
towards the Segment. All non-DF PEs continue to drop multi- if such need every arises.
destination traffic (for the associated EVIs) in the egress direction
towards the Segment. 4. The PE that is elected as a DF for a given EVPN instance will
unblock traffic for the Ethernet Tags associated with that EVPN
instance. Note that the DF PE unblocks multi-destination traffic in
the egress direction towards the Segment. All non-DF PEs continue to
drop multi-destination traffic (for the associated EVPN instances) in
the egress direction towards the Segment.
In the case of link or port failure, the affected PE withdraws its In the case of link or port failure, the affected PE withdraws its
Ethernet Segment route. This will re-trigger the service carving Ethernet Segment route. This will re-trigger the service carving
procedures on all the PEs in the RG. For PE node failure, or upon PE procedures on all the PEs in the RG. For PE node failure, or upon PE
commissioning or decommissioning, the PEs re-trigger the service commissioning or decommissioning, the PEs re-trigger the service
carving. In case of a Single-Active multi-homing, when a service carving. In case of a Single-Active multi-homing, when a service
moves from one PE in the RG to another PE as a result of re-carving, moves from one PE in the RG to another PE as a result of re-carving,
the PE, which ends up being the elected DF for the service, must the PE, which ends up being the elected DF for the service, must
trigger a MAC address flush notification towards the associated trigger a MAC address flush notification towards the associated
Ethernet Segment. This can be done, for e.g. using IEEE 802.1ak MVRP Ethernet Segment. This can be done, for e.g. using IEEE 802.1ak MVRP
'new' declaration. 'new' declaration.
9.6. Interoperability with Single-homing PEs
Let's refer to PEs that only support single-homed CE devices as
single-homing PEs. For single-homing PEs, all the above multi-homing
procedures can be omitted; however, to allow for single-homing PEs to
fully inter-operate with multi-homing PEs, some of the multi-homing
procedures described above SHOULD be supported even by single-homing
PEs:
- procedures related to processing Ethernet A-D route for the purpose
of Fast Convergence (9.2 Fast Convergence), to let single-homing PEs
benefit from fast convergence
- procedures related to processing Ethernet A-D route for the purpose
of Aliasing (9.4 Aliasing and Backup-path), to let single-homing PEs
benefit from load balancing
- procedures related to processing Ethernet A-D route for the purpose
of Backup-path (9.4 Aliasing and Backup-path), to let single-homing
PEs to benefit from the corresponding convergence improvement
10. Determining Reachability to Unicast MAC Addresses 10. Determining Reachability to Unicast MAC Addresses
PEs forward packets that they receive based on the destination MAC PEs forward packets that they receive based on the destination MAC
address. This implies that PEs must be able to learn how to reach a address. This implies that PEs must be able to learn how to reach a
given destination unicast MAC address. given destination unicast MAC address.
There are two components to MAC address learning, "local learning" There are two components to MAC address learning, "local learning"
and "remote learning": and "remote learning":
10.1. Local Learning 10.1. Local Learning
A particular PE must be able to learn the MAC addresses from the CEs A particular PE must be able to learn the MAC addresses from the CEs
that are connected to it. This is referred to as local learning. that are connected to it. This is referred to as local learning.
The PEs in a particular E-VPN MUST support local data plane learning The PEs in a particular EVPN instance MUST support local data plane
using standard IEEE Ethernet learning procedures. An PE must be learning using standard IEEE Ethernet learning procedures. An PE must
capable of learning MAC addresses in the data plane when it receives be capable of learning MAC addresses in the data plane when it
packets such as the following from the CE network: receives packets such as the following from the CE network:
- DHCP requests - DHCP requests
- ARP request for its own MAC. - ARP request for its own MAC.
- ARP request for a peer. - ARP request for a peer.
Alternatively PEs MAY learn the MAC addresses of the CEs in the Alternatively PEs MAY learn the MAC addresses of the CEs in the
control plane or via management plane integration between the PEs and control plane or via management plane integration between the PEs and
the CEs. the CEs.
skipping to change at page 25, line 44 skipping to change at page 26, line 21
10.2. Remote learning 10.2. Remote learning
A particular PE must be able to determine how to send traffic to MAC A particular PE must be able to determine how to send traffic to MAC
addresses that belong to or are behind CEs connected to other PEs addresses that belong to or are behind CEs connected to other PEs
i.e. to remote CEs or hosts behind remote CEs. We call such MAC i.e. to remote CEs or hosts behind remote CEs. We call such MAC
addresses as "remote" MAC addresses. addresses as "remote" MAC addresses.
This document requires an PE to learn remote MAC addresses in the This document requires an PE to learn remote MAC addresses in the
control plane. In order to achieve this, each PE advertises the MAC control plane. In order to achieve this, each PE advertises the MAC
addresses it learns from its locally attached CEs in the control addresses it learns from its locally attached CEs in the control
plane, to all the other PEs in the EVI, using MP-BGP and specifically plane, to all the other PEs in that EVPN instance, using MP-BGP and
the MAC Advertisement route. specifically the MAC Advertisement route.
10.2.1. Constructing the BGP E-VPN MAC Address Advertisement 10.2.1. Constructing the BGP EVPN MAC Address Advertisement
BGP is extended to advertise these MAC addresses using the MAC BGP is extended to advertise these MAC addresses using the MAC
Advertisement route type in the E-VPN NLRI. Advertisement route type in the EVPN NLRI.
The RD MUST be the RD of the EVI that is advertising the NLRI. The The RD MUST be the RD of the EVI that is advertising the NLRI. The
procedures for setting the RD for a given EVI are described in procedures for setting the RD for a given EVI are described in
section 9.4.1. section 9.4.1.
The Ethernet Segment Identifier is set to the ten octet ESI described The Ethernet Segment Identifier is set to the ten octet ESI described
in section "Ethernet Segment". in section "Ethernet Segment".
The Ethernet Tag ID may be zero or may represent a valid Ethernet Tag The Ethernet Tag ID may be zero or may represent a valid Ethernet Tag
ID. This field may be non-zero when there are multiple bridge ID. This field may be non-zero when there are multiple bridge
domains in the EVI (e.g., the PE needs to perform qualified learning domains in the MAC-VRF (e.g., the PE needs to perform qualified
for the VLANs in that EVI). learning for the VLANs in that MAC-VRF).
When the the Ethernet Tag ID in the NLRI is set to a non-zero value, When the the Ethernet Tag ID in the NLRI is set to a non-zero value,
for a particular bridge domain, then this Ethernet Tag may either be for a particular bridge domain, then this Ethernet Tag may either be
the Ethernet tag value associated with the CE, e.g., VLAN ID, or it the Ethernet tag value associated with the CE, e.g., VLAN ID, or it
may be the Ethernet Tag Identifier, e.g., VLAN ID assigned by the E- may be the Ethernet Tag Identifier, e.g., VLAN ID assigned by the
VPN provider and mapped to the CE's Ethernet tag. The latter would be EVPN provider and mapped to the CE's Ethernet tag. The latter would
the case if the CE Ethernet tags, e.g., VLAN ID, for a particular be the case if the CE Ethernet tags, e.g., VLAN ID, for a particular
bridge domain are different on different CEs. bridge domain are different on different CEs.
The MAC address length field is typically set to 48. However this The MAC address length field is in bits and it is typically set to
specification enables specifying the MAC address as a prefix; in 48. However this specification enables specifying the MAC address as
which case, the MAC address length field is set to the length of the a prefix; in which case, the MAC address length field is set to the
prefix. This provides the ability to aggregate MAC addresses if the length of the prefix. This provides the ability to aggregate MAC
deployment environment supports that. The encoding of a MAC address addresses if the deployment environment supports that. The encoding
MUST be the 6-octet MAC address specified by [802.1D-ORIG] [802.1D- of a MAC address MUST be the 6-octet MAC address specified by
REV]. If the MAC address is advertised as a prefix then the trailing [802.1D-ORIG] [802.1D-REV]. If the MAC address is advertised as a
bits of the prefix MUST be set to 0 to ensure that the entire prefix prefix then the trailing bits of the prefix MUST be set to 0 to
is encoded as 6 octets. ensure that the entire prefix is encoded as 6 octets.
The IP Address Length field value is set to the number of octets in
the IP Address field.
The IP Address field is optional. By default, the IP Address Length The IP Address field is optional. By default, the IP Address Length
field is set to 0 and the IP address field is omitted from the route. field is set to 0 and the IP address field is omitted from the route.
When a valid IP address needs to be advertised (e.g., for ARP When a valid IP address or address prefix needs to be advertised
suppression purposes or for inter-subnet switching), it is then (e.g., for ARP suppression purposes or for inter-subnet switching),
encoded in this route. it is then encoded in this route.
The MPLS label field carries one or more labels (that corresponds to The IP Address Length field is in bits and it is the length of the IP
the stack of labels [MPLS-ENCAPS]). Each label is encoded as 3 prefix. This provides the ability to advertise IP address prefixes
octets, where the high-order 20 bits contain the label value, and the when the deployment environment supports that. The encoding of an IP
low order bit contains "Bottom of Stack" (as defined in [MPLS- address MUST be either 4 octets for IPv4 or 16 octets for IPv6. When
ENCAPS]). The MPLS label stack MUST be the downstream assigned E-VPN the IP address is advertised as a prefix, then the trailing bits of
MPLS label stack that is used by the PE to forward MPLS-encapsulated the prefix MUST be set to 0 to ensure that the entire prefix is
Ethernet frames received from remote PEs, where the destination MAC encoded as either 4 or 16 octets. The length field of EVPN NLRI
(which is in octets and is described in section 8) is sufficient to
determine whether an IP address/prefix is encoded in this route and
if so, whether the encoded IP address/prefix is IPV4 or IPv6.
The MPLS label field carries a single label and it is encoded as 3
octets, where the high-order 20 bits contain the label value. The
MPLS label MUST be the downstream assigned that is used by the PE to
forward MPLS-encapsulated Ethernet frames, where the destination MAC
address in the Ethernet frame is the MAC address advertised in the address in the Ethernet frame is the MAC address advertised in the
above NLRI. The forwarding procedures are specified in section above NLRI. The forwarding procedures are specified in section
"Forwarding Unicast Packets" and "Load Balancing of Unicast Packets". "Forwarding Unicast Packets" and "Load Balancing of Unicast Packets".
An PE may advertise the same single E-VPN label for all MAC addresses An PE may advertise the same single EVPN label for all MAC addresses
in a given EVI. This label assignment methodology is referred to as a in a given EVI. This label assignment methodology is referred to as a
per EVI label assignment. Alternatively, an PE may advertise a unique per EVI label assignment. Alternatively, an PE may advertise a unique
E-VPN label per <ESI, Ethernet Tag> combination. This label EVPN label per <ESI, Ethernet Tag> combination. This label assignment
assignment methodology is referred to as a per <ESI, Ethernet Tag> methodology is referred to as a per <ESI, Ethernet Tag> label
label assignment. As a third option, an PE may advertise a unique E- assignment. As a third option, an PE may advertise a unique EVPN
VPN label per MAC address. All of these methodologies have their label per MAC address. All of these methodologies have their
tradeoffs. tradeoffs. The choice of a particular label assignment methodology is
purely local to the PE that originates the route.
Per EVI label assignment requires the least number of E-VPN labels, Per EVI label assignment requires the least number of EVPN labels,
but requires a MAC lookup in addition to an MPLS lookup on an egress but requires a MAC lookup in addition to an MPLS lookup on an egress
PE for forwarding. On the other hand, a unique label per <ESI, PE for forwarding. On the other hand, a unique label per <ESI,
Ethernet Tag> or a unique label per MAC allows an egress PE to Ethernet Tag> or a unique label per MAC allows an egress PE to
forward a packet that it receives from another PE, to the connected forward a packet that it receives from another PE, to the connected
CE, after looking up only the MPLS labels without having to perform a CE, after looking up only the MPLS labels without having to perform a
MAC lookup. This includes the capability to perform appropriate VLAN MAC lookup. This includes the capability to perform appropriate VLAN
ID translation on egress to the CE. ID translation on egress to the CE.
The Next Hop field of the MP_REACH_NLRI attribute of the route MUST The Next Hop field of the MP_REACH_NLRI attribute of the route MUST
be set to the IPv4 or IPv6 address of the advertising PE. be set to the IPv4 or IPv6 address of the advertising PE.
The BGP advertisement for the MAC advertisement route MUST also carry The BGP advertisement for the MAC advertisement route MUST also carry
one or more Route Target (RT) attributes. RTs may be configured (as one or more Route Target (RT) attributes. RTs may be configured (as
in IP VPNs), or may be derived automatically from the Ethernet Tag in IP VPNs), or may be derived automatically from the Ethernet Tag
ID, in the Unique VLAN case, as described in section "Ethernet A-D ID, in the Unique VLAN case, as described in section "Ethernet A-D
Route per E-VPN". Route per EVPN".
It is to be noted that this document does not require PEs to create It is to be noted that this document does not require PEs to create
forwarding state for remote MACs when they are learnt in the control forwarding state for remote MACs when they are learnt in the control
plane. When this forwarding state is actually created is a local plane. When this forwarding state is actually created is a local
implementation matter. implementation matter.
10.2.2 Route Resolution 10.2.2 Route Resolution
If the Ethernet Segment Identifier field in a received MAC If the Ethernet Segment Identifier field in a received MAC
Advertisement route is set to the reserved ESI value of 0 or MAX-ESI, Advertisement route is set to the reserved ESI value of 0 or MAX-ESI,
skipping to change at page 28, line 35 skipping to change at page 29, line 19
route, then PE3 would have continued forwarding traffic destined to route, then PE3 would have continued forwarding traffic destined to
M1 to PE2. M1 to PE2.
11. ARP and ND 11. ARP and ND
The IP address field in the MAC advertisement route may optionally The IP address field in the MAC advertisement route may optionally
carry one of the IP addresses associated with the MAC address. This carry one of the IP addresses associated with the MAC address. This
provides an option which can be used to minimize the flooding of ARP provides an option which can be used to minimize the flooding of ARP
or Neighbor Discovery (ND) messages over the MPLS network and to or Neighbor Discovery (ND) messages over the MPLS network and to
remote CEs. This option also minimizes ARP (or ND) message processing remote CEs. This option also minimizes ARP (or ND) message processing
on end-stations/hosts connected to the E-VPN network. An PE may learn on end-stations/hosts connected to the EVPN network. An PE may learn
the IP address associated with a MAC address in the control or the IP address associated with a MAC address in the control or
management plane between the CE and the PE. Or, it may learn this management plane between the CE and the PE. Or, it may learn this
binding by snooping certain messages to or from a CE. When an PE binding by snooping certain messages to or from a CE. When an PE
learns the IP address associated with a MAC address, of a locally learns the IP address associated with a MAC address, of a locally
connected CE, it may advertise this address to other PEs by including connected CE, it may advertise this address to other PEs by including
it in the MAC Advertisement route. The IP Address may be an IPv4 it in the MAC Advertisement route. The IP Address may be an IPv4
address encoded using four octets, or an IPv6 address encoded using address encoded using four octets, or an IPv6 address encoded using
sixteen octets. The IP Address length field MUST be set to 32 for an sixteen octets. The IP Address length field MUST be set to 32 for an
IPv4 address or to 128 for an IPv6 address. IPv4 address or to 128 for an IPv6 address.
If there are multiple IP addresses associated with a MAC address, If there are multiple IP addresses associated with a MAC address,
then multiple MAC advertisement routes MUST be generated, one for then multiple MAC advertisement routes MUST be generated, one for
each IP address. For instance, this may be the case when there are each IP address. For instance, this may be the case when there are
both an IPv4 and an IPv6 address associated with the MAC address. both an IPv4 and an IPv6 address associated with the MAC address.
When the IP address is dissociated with the MAC address, then the MAC When the IP address is dissociated with the MAC address, then the MAC
advertisement route with that particular IP address MUST be advertisement route with that particular IP address MUST be
withdrawn. withdrawn.
When an PE receives an ARP request for an IP address from a CE, and When an PE receives an ARP request for an IP address from a CE, and
if the PE has the MAC address binding for that IP address, the PE if the PE has the MAC address binding for that IP address, the PE
SHOULD perform ARP proxy and respond to the ARP request. SHOULD perform ARP proxy by responding to the ARP request.
11.1 Default Gateway 11.1 Default Gateway
A PE MAY choose to terminate ARP messages instead of performing ARP When a PE needs to perform inter-subnet forwarding where each subnet
proxy for them. Such scenarios arises when the PE needs to perform is represented by a different broadcast domain (e.g., different VLAN)
inter-subnet forwarding where each subnet is represented by a the inter-subnet forwarding is performed at layer 3 and the PE that
different bridge domain/EVI. In such scenarios the inter-subnet performs such function is called the default gateway. In this case
forwarding is performed at layer 3 and the PE that performs such when the PE receives an ARP Request for the IP address of the default
function is called the default gateway. gateway, the PE originates an ARP Reply.
Each PE that acts as a default gateway for a given E-VPN advertises Each PE that acts as a default gateway for a given EVPN instance MAY
in the E-VPN control plane its default gateway IP and MAC address advertise in the EVPN control plane its default gateway MAC address
using the MAC advertisement route, and indicates that such route is using the MAC advertisement route, and indicates that such route is
associated with the default gateway. This is accomplished by associated with the default gateway. This is accomplished by
requiring the route to carry the Default Gateway extended community requiring the route to carry the Default Gateway extended community
defined in [Section 8.8 Default Gateway Extended Community]. defined in [Section 8.8 Default Gateway Extended Community]. The IP
address field (4 octets for IPv4, 16 octets for IPv6) is set to zero
when advertising the MAC route with the Default Gateway extended
community. Both ESI and Ethernet Tag fields are also set to zero for
this advertisement.
Unless it is known a priori (by means outside of this document) that
all PEs of a given EVPN instance act as a default gateway for that
EVPN instance, the MPLS label MUST be set to a valid downstream
assigned label.
Furthermore, even if all PEs of a given EVPN instance do act as a
default gateway for that EVPN instance, but only some, but not all,
of these PEs have sufficient (routing) information to provide inter-
subnet routing for all the inter-subnet traffic originated within the
subnet associated with the EVPN instance, then when such PE
advertises in the EVPN control plane its default gateway MAC address
using the MAC advertisement route, and indicates that such route is
associated with the default gateway, the route MUST carry a valid
downstream assigned label.
If all PEs of a given EVPN instance act as a default gateway for that
EVPN instance, and the same default gateway MAC address is used
across all gateway devices, then no such advertisement is needed.
However, if each default gateway uses a different MAC address, then
each default gateway needs to be aware of other gateways' MAC
addresses and thus the need for such advertisement. This is called
MAC address aliasing since a single default GW can be represented by
multiple MAC addresses.
Each PE that receives this route and imports it as per procedures Each PE that receives this route and imports it as per procedures
specified in this document follows the procedures in this section specified in this document follows the procedures in this section
when replying to ARP Requests that it receives if such Requests are when replying to ARP Requests that it receives if such Requests are
for the IP address in the received E-VPN route. for the IP address in the received EVPN route.
Each PE that acts as a default gateway for a given E-VPN that Each PE that acts as a default gateway for a given EVPN instance that
receives this route and imports it as per procedures specified in receives this route and imports it as per procedures specified in
this document MUST create MAC forwarding state that enables it to this document MUST create MAC forwarding state that enables it to
apply IP forwarding to the packets destined to the MAC address apply IP forwarding to the packets destined to the MAC address
carried in the route. carried in the route.
12. Handling of Multi-Destination Traffic 12. Handling of Multi-Destination Traffic
Procedures are required for a given PE to send broadcast or multicast Procedures are required for a given PE to send broadcast or multicast
traffic, received from a CE encapsulated in a given Ethernet Tag in traffic, received from a CE encapsulated in a given Ethernet Tag
an EVI, to all the other PEs that span that Ethernet Tag in the EVI. (VLAN) in an EVPN instance, to all the other PEs that span that
In certain scenarios, described in section "Processing of Unknown Ethernet Tag (VLAN) in that EVPN instance. In certain scenarios,
Unicast Packets", a given PE may also need to flood unknown unicast described in section "Processing of Unknown Unicast Packets", a given
traffic to other PEs. PE may also need to flood unknown unicast traffic to other PEs.
The PEs in a particular E-VPN may use ingress replication, P2MP LSPs The PEs in a particular EVPN instance may use ingress replication,
or MP2MP LSPs to send unknown unicast, broadcast or multicast traffic P2MP LSPs or MP2MP LSPs to send unknown unicast, broadcast or
to other PEs. multicast traffic to other PEs.
Each PE MUST advertise an "Inclusive Multicast Ethernet Tag Route" to Each PE MUST advertise an "Inclusive Multicast Ethernet Tag Route" to
enable the above. The following subsection provides the procedures to enable the above. The following subsection provides the procedures to
construct the Inclusive Multicast Ethernet Tag route. Subsequent construct the Inclusive Multicast Ethernet Tag route. Subsequent
subsections describe in further detail its usage. subsections describe in further detail its usage.
12.1. Construction of the Inclusive Multicast Ethernet Tag Route 12.1. Construction of the Inclusive Multicast Ethernet Tag Route
The RD MUST be the RD of the EVI that is advertising the NLRI. The The RD MUST be the RD of the EVI that is advertising the NLRI. The
procedures for setting the RD for a given E-VPN are described in procedures for setting the RD for a given EVPN instance on a PE are
section 9.4.1. described in section 9.4.1.
The Ethernet Tag ID is the identifier of the Ethernet Tag. It MAY be The Ethernet Tag ID is the identifier of the Ethernet Tag. It MAY be
set to 0 or to a valid Ethernet Tag value. set to 0 or to a valid Ethernet Tag value.
The Originating Router's IP address MUST be set to an IP address of The Originating Router's IP address MUST be set to an IP address of
the PE. This address SHOULD be common for all the EVIs on the PE the PE. This address SHOULD be common for all the EVIs on the PE
(e.,g., this address may be PE's loopback address). (e.,g., this address may be PE's loopback address). The IP Address
Length field is in bits.
The Next Hop field of the MP_REACH_NLRI attribute of the route MUST The Next Hop field of the MP_REACH_NLRI attribute of the route MUST
be set to the same IP address as the one carried in the Originating be set to the same IP address as the one carried in the Originating
Router's IP Address field. Router's IP Address field.
The BGP advertisement for the Inclusive Multicast Ethernet Tag route The BGP advertisement for the Inclusive Multicast Ethernet Tag route
MUST also carry one or more Route Target (RT) attributes. The MUST also carry one or more Route Target (RT) attributes. The
assignment of RTs described in the section on "Constructing the BGP assignment of RTs described in the section on "Constructing the BGP
E-VPN MAC Address Advertisement" MUST be followed. EVPN MAC Address Advertisement" MUST be followed.
12.2. P-Tunnel Identification 12.2. P-Tunnel Identification
In order to identify the P-Tunnel used for sending broadcast, unknown In order to identify the P-Tunnel used for sending broadcast, unknown
unicast or multicast traffic, the Inclusive Multicast Ethernet Tag unicast or multicast traffic, the Inclusive Multicast Ethernet Tag
route MUST carry a "PMSI Tunnel Attribute" as specified in [BGP route MUST carry a "PMSI Tunnel Attribute" as specified in [BGP
MVPN]. MVPN].
Depending on the technology used for the P-tunnel for the E-VPN on Depending on the technology used for the P-tunnel for the EVPN
the PE, the PMSI Tunnel attribute of the Inclusive Multicast Ethernet instance on the PE, the PMSI Tunnel attribute of the Inclusive
Tag route is constructed as follows. Multicast Ethernet Tag route is constructed as follows.
+ If the PE that originates the advertisement uses a + If the PE that originates the advertisement uses a
P-Multicast tree for the P-tunnel for E-VPN, the PMSI P-Multicast tree for the P-tunnel for EVPN, the PMSI
Tunnel attribute MUST contain the identity of the tree Tunnel attribute MUST contain the identity of the tree
(note that the PE could create the identity of the (note that the PE could create the identity of the
tree prior to the actual instantiation of the tree). tree prior to the actual instantiation of the tree).
+ An PE that uses a P-Multicast tree for the P-tunnel MAY + An PE that uses a P-Multicast tree for the P-tunnel MAY
aggregate two or more Ethernet Tags in the same or different aggregate two or more Ethernet Tags in the same or different
EVIs present on the PE onto the same tree. In this case, in EVIs present on the PE onto the same tree. In this case, in
addition to carrying the identity of the tree, the PMSI Tunnel addition to carrying the identity of the tree, the PMSI Tunnel
attribute MUST carry an MPLS upstream assigned label which attribute MUST carry an MPLS upstream assigned label which
the PE has bound uniquely to the Ethernet Tag for the EVI the PE has bound uniquely to the Ethernet Tag for the EVI
associated with this update (as determined by its RTs). associated with this update (as determined by its RTs).
If the PE has already advertised Inclusive Multicast If the PE has already advertised Inclusive Multicast
Ethernet Tag routes for two or more Ethernet Tags that it Ethernet Tag routes for two or more Ethernet Tags that it
now desires to aggregate, then the PE MUST re-advertise now desires to aggregate, then the PE MUST re-advertise
those routes. The re-advertised routes MUST be the same those routes. The re-advertised routes MUST be the same
as the original ones, except for the PMSI Tunnel attribute as the original ones, except for the PMSI Tunnel attribute
and the label carried in that attribute. and the label carried in that attribute.
+ If the PE that originates the advertisement uses ingress + If the PE that originates the advertisement uses ingress
replication for the P-tunnel for E-VPN, the route MUST replication for the P-tunnel for EVPN, the route MUST
include the PMSI Tunnel attribute with the Tunnel Type set to include the PMSI Tunnel attribute with the Tunnel Type set to
Ingress Replication and Tunnel Identifier set to a routable Ingress Replication and Tunnel Identifier set to a routable
address of the PE. The PMSI Tunnel attribute MUST carry a address of the PE. The PMSI Tunnel attribute MUST carry a
downstream assigned MPLS label. This label is used to downstream assigned MPLS label. This label is used to
demultiplex the broadcast, multicast or unknown unicast E-VPN demultiplex the broadcast, multicast or unknown unicast EVPN
traffic received over a MP2P tunnel by the PE. traffic received over a MP2P tunnel by the PE.
+ The Leaf Information Required flag of the PMSI Tunnel + The Leaf Information Required flag of the PMSI Tunnel
attribute MUST be set to zero, and MUST be ignored on receipt. attribute MUST be set to zero, and MUST be ignored on receipt.
13. Processing of Unknown Unicast Packets 13. Processing of Unknown Unicast Packets
The procedures in this document do not require the PEs to flood The procedures in this document do not require the PEs to flood
unknown unicast traffic to other PEs. If PEs learn CE MAC addresses unknown unicast traffic to other PEs. If PEs learn CE MAC addresses
via a control plane protocol, the PEs can then distribute MAC via a control plane protocol, the PEs can then distribute MAC
addresses via BGP, and all unicast MAC addresses will be learnt prior addresses via BGP, and all unicast MAC addresses will be learnt prior
to traffic to those destinations. to traffic to those destinations.
However, if a destination MAC address of a received packet is not However, if a destination MAC address of a received packet is not
known by the PE, the PE may have to flood the packet. Flooding must known by the PE, the PE may have to flood the packet. When flooding,
take into account "split horizon forwarding" as follows: The one must take into account "split horizon forwarding" as follows: The
principles behind the following procedures are borrowed from the principles behind the following procedures are borrowed from the
split horizon forwarding rules in VPLS solutions [RFC4761] and split horizon forwarding rules in VPLS solutions [RFC4761] and
[RFC4762]. When an PE capable of flooding (say PEx) receives a
broadcast or multicast Ethernet frame, or one with an unknown [RFC4762]. When an PE capable of flooding (say PEx) receives an
destination MAC address, it must flood the frame. If the frame unknown destination MAC address, it floods the frame. If the frame
arrived from an attached CE, PEx must send a copy of the frame to arrived from an attached CE, PEx must send a copy of the frame to
every other attached CE participating in the EVI, on a different ESI every other attached CE participating in that EVPN instance, on a
than the one it received the frame on, as long as the PE is the DF different ESI than the one it received the frame on, as long as the
for the egress ESI. In addition, the PE must flood the frame to all PE is the DF for the egress ESI. In addition, the PE must flood the
other PEs participating in the EVI. If, on the other hand, the frame frame to all other PEs participating in that EVPN instance. If, on
arrived from another PE (say PEy), PEx must send a copy of the packet the other hand, the frame arrived from another PE (say PEy), PEx must
only to attached CEs as long as it is the DF for the egress ESI. PEx send a copy of the packet only to attached CEs as long as it is the
MUST NOT send the frame to other PEs, since PEy would have already DF for the egress ESI. PEx MUST NOT send the frame to other PEs,
done so. Split horizon forwarding rules apply to broadcast and since PEy would have already done so. Split horizon forwarding rules
multicast packets, as well as packets to an unknown MAC address. apply to unknown MAC addresses.
Whether or not to flood packets to unknown destination MAC addresses Whether or not to flood packets to unknown destination MAC addresses
should be an administrative choice, depending on how learning happens should be an administrative choice, depending on how learning happens
between CEs and PEs. between CEs and PEs.
The PEs in a particular E-VPN may use ingress replication using RSVP- The PEs in a particular EVPN instance may use ingress replication
TE P2P LSPs or LDP MP2P LSPs for sending broadcast, multicast and using RSVP-TE P2P LSPs or LDP MP2P LSPs for sending unknown unicast
unknown unicast traffic to other PEs. Or they may use RSVP-TE P2MP or traffic to other PEs. Or they may use RSVP-TE P2MP or LDP P2MP for
LDP P2MP or LDP MP2MP LSPs for sending such traffic to other PEs. sending such traffic to other PEs.
13.1. Ingress Replication 13.1. Ingress Replication
If ingress replication is in use, the P-Tunnel attribute, carried in If ingress replication is in use, the P-Tunnel attribute, carried in
the Inclusive Multicast Ethernet Tag routes for the EVI, specifies the Inclusive Multicast Ethernet Tag routes for the EVPN instance,
the downstream label that the other PEs can use to send unknown specifies the downstream label that the other PEs can use to send
unicast, multicast or broadcast traffic for the EVI to this unknown unicast, multicast or broadcast traffic for that EVPN
particular PE. instance to this particular PE.
The PE that receives a packet with this particular MPLS label MUST The PE that receives a packet with this particular MPLS label MUST
treat the packet as a broadcast, multicast or unknown unicast packet. treat the packet as a broadcast, multicast or unknown unicast packet.
Further if the MAC address is a unicast MAC address, the PE MUST Further if the MAC address is a unicast MAC address, the PE MUST
treat the packet as an unknown unicast packet. treat the packet as an unknown unicast packet.
13.2. P2MP MPLS LSPs 13.2. P2MP MPLS LSPs
The procedures for using P2MP LSPs are very similar to VPLS The procedures for using P2MP LSPs are very similar to VPLS
procedures [VPLS-MCAST]. The P-Tunnel attribute used by an PE for procedures [VPLS-MCAST]. The P-Tunnel attribute used by an PE for
sending unknown unicast, broadcast or multicast traffic for a sending unknown unicast, broadcast or multicast traffic for a
particular EVI is advertised in the Inclusive Ethernet Tag Multicast particular EVPN instance is advertised in the Inclusive Ethernet Tag
route as described in section "Handling of Multi-Destination Multicast route as described in section "Handling of Multi-
Traffic". Destination Traffic".
The P-Tunnel attribute specifies the P2MP LSP identifier. This is the The P-Tunnel attribute specifies the P2MP LSP identifier. This is the
equivalent of an Inclusive tree in [VPLS-MCAST]. Note that multiple equivalent of an Inclusive tree in [VPLS-MCAST]. Note that multiple
Ethernet Tags, which may be in different EVIs, may use the same P2MP Ethernet Tags, which may be in different EVPN instances, may use the
LSP, using upstream labels [VPLS-MCAST]. This is the equivalent of an same P2MP LSP, using upstream labels [VPLS-MCAST]. This is the
Aggregate Inclusive tree in [VPLS-MCAST]. When P2MP LSPs are used for equivalent of an Aggregate Inclusive tree in [VPLS-MCAST]. When P2MP
flooding unknown unicast traffic, packet re-ordering is possible. LSPs are used for flooding unknown unicast traffic, packet re-
ordering is possible.
The PE that receives a packet on the P2MP LSP specified in the PMSI The PE that receives a packet on the P2MP LSP specified in the PMSI
Tunnel Attribute MUST treat the packet as a broadcast, multicast or Tunnel Attribute MUST treat the packet as a broadcast, multicast or
unknown unicast packet. Further if the MAC address is a unicast MAC unknown unicast packet. Further if the MAC address is a unicast MAC
address, the PE MUST treat the packet as an unknown unicast packet. address, the PE MUST treat the packet as an unknown unicast packet.
14. Forwarding Unicast Packets 14. Forwarding Unicast Packets
This section describes procedures for forwarding unicast packets by
PEs, where such packets are received from either directly connected
CEs, or from some other PEs.
14.1. Forwarding packets received from a CE 14.1. Forwarding packets received from a CE
When an PE receives a packet from a CE, on a given Ethernet Tag, it When an PE receives a packet from a CE, on a given Ethernet Tag, it
must first look up the source MAC address of the packet. In certain must first look up the source MAC address of the packet. In certain
environments the source MAC address MAY be used to authenticate the environments the source MAC address MAY be used to authenticate the
CE and determine that traffic from the host can be allowed into the CE and determine that traffic from the host can be allowed into the
network. Source MAC lookup MAY also be used for local MAC address network. Source MAC lookup MAY also be used for local MAC address
learning. learning.
If the PE decides to forward the packet, the destination MAC address If the PE decides to forward the packet, the destination MAC address
of the packet must be looked up. If the PE has received MAC address of the packet must be looked up. If the PE has received MAC address
advertisements for this destination MAC address from one or more advertisements for this destination MAC address from one or more
other PEs or learned it from locally connected CEs, it is considered other PEs or learned it from locally connected CEs, it is considered
as a known MAC address. Otherwise, the MAC address is considered as as a known MAC address. Otherwise, the MAC address is considered as
an unknown MAC address. an unknown MAC address.
For known MAC addresses the PE forwards this packet to one of the For known MAC addresses the PE forwards this packet to one of the
remote PEs or to a locally attached CE. When forwarding to a remote remote PEs or to a locally attached CE. When forwarding to a remote
PE, the packet is encapsulated in the E-VPN MPLS label advertised by PE, the packet is encapsulated in the EVPN MPLS label advertised by
the remote PE, for that MAC address, and in the MPLS LSP label stack the remote PE, for that MAC address, and in the MPLS LSP label stack
to reach the remote PE. to reach the remote PE.
If the MAC address is unknown and if the administrative policy on the If the MAC address is unknown and if the administrative policy on the
PE requires flooding of unknown unicast traffic then: PE requires flooding of unknown unicast traffic then:
- The PE MUST flood the packet to other PEs. The - The PE MUST flood the packet to other PEs. The PE MUST first
PE MUST first encapsulate the packet in the ESI MPLS encapsulate the packet in the ESI MPLS label as described in section
label as described in section 9.3. 9.3. If ingress replication is used, the packet MUST be replicated
If ingress replication is used, the packet MUST be replicated one or more times to each remote PE with the outermost label being an
one or more times to each remote PE with the outermost MPLS label determined as follows: This is the MPLS label advertised
label being an MPLS label determined as follows: This by the remote PE in a PMSI Tunnel Attribute in the Inclusive
is the MPLS label advertised by the remote PE in a PMSI Multicast Ethernet Tag route for an <EVPN instance, Ethernet Tag>
Tunnel Attribute in the Inclusive Multicast Ethernet Tag combination. The Ethernet Tag in the route must be the same as the
route for an <EVI, Ethernet Tag> combination. The Ethernet Ethernet Tag associated with the interface on which the ingress PE
Tag in the route must be the same as the Ethernet Tag receives the packet. If P2MP LSPs are being used the packet MUST be
associated with the interface on which the ingress PE sent on the P2MP LSP that the PE is the root of for the Ethernet Tag
receives the packet. If P2MP LSPs are being used the packet in the EVPN instance. If the same P2MP LSP is used for all Ethernet
MUST be sent on the P2MP LSP that the PE is the root of for Tags, then all the PEs in the EVPN instance MUST be the leaves of the
the Ethernet Tag in the EVI. If the same P2MP LSP is used P2MP LSP. If a distinct P2MP LSP is used for a given Ethernet Tag in
for all Ethernet Tags, then all the PEs in the EVI MUST the EVPN instance, then only the PEs in the Ethernet Tag MUST be the
be the leaves of the P2MP LSP. If a distinct P2MP LSP is leaves of the P2MP LSP. The packet MUST be encapsulated in the P2MP
used for a given Ethernet Tag in the EVI, then only the LSP label stack.
PEs in the Ethernet Tag MUST be the leaves of the P2MP
LSP. The packet MUST be encapsulated in the P2MP LSP label
stack.
If the MAC address is unknown then, if the administrative policy on If the MAC address is unknown then, if the administrative policy on
the PE does not allow flooding of unknown unicast traffic: the PE does not allow flooding of unknown unicast traffic:
- The PE MUST drop the packet. - The PE MUST drop the packet.
14.2. Forwarding packets received from a remote PE 14.2. Forwarding packets received from a remote PE
This section described the procedures for forwarding known and
unknown unicast packets received from a remote PE.
14.2.1. Unknown Unicast Forwarding 14.2.1. Unknown Unicast Forwarding
When an PE receives an MPLS packet from a remote PE then, after When an PE receives an MPLS packet from a remote PE then, after
processing the MPLS label stack, if the top MPLS label ends up being processing the MPLS label stack, if the top MPLS label ends up being
a P2MP LSP label associated with an EVI or the downstream label a P2MP LSP label associated with an EVPN instance or in case of
advertised in the P-Tunnel attribute, and after performing the split ingress replication the downstream label advertised in the P-Tunnel
horizon procedures described in section "Split Horizon": attribute, and after performing the split horizon procedures
described in section "Split Horizon":
- If the PE is the designated forwarder of unknown unicast, broadcast - If the PE is the designated forwarder of BUM traffic on a
or multicast traffic, on a particular set of ESIs for the Ethernet particular set of ESIs for the Ethernet Tag, the default behavior is
Tag, the default behavior is for the PE to flood the packet on these for the PE to flood the packet on these ESIs. In other words, the
ESIs. In other words, the default behavior is for the PE to assume default behavior is for the PE to assume that for BUM traffic, it is
that the destination MAC address is unknown unicast, broadcast or not required to perform a destination MAC address lookup. As an
multicast and it is not required to perform a destination MAC address option, the PE may perform a destination MAC lookup to flood the
lookup. As an option, the PE may perform a destination MAC lookup to packet to only a subset of the CE interfaces in the Ethernet Tag. For
flood the packet to only a subset of the CE interfaces in the instance the PE may decide to not flood an BUM packet on certain
Ethernet Tag. For instance the PE may decide to not flood an unknown Ethernet segments even if it is the DF on the Ethernet segment, based
unicast packet on certain Ethernet segments even if it is the DF on on administrative policy.
the Ethernet segment, based on administrative policy.
- If the PE is not the designated forwarder on any of the ESIs for - If the PE is not the designated forwarder on any of the ESIs for
the Ethernet Tag, the default behavior is for it to drop the packet. the Ethernet Tag, the default behavior is for it to drop the packet.
14.2.2. Known Unicast Forwarding 14.2.2. Known Unicast Forwarding
If the top MPLS label ends up being an E-VPN label that was If the top MPLS label ends up being an EVPN label that was advertised
advertised in the unicast MAC advertisements, then the PE either in the unicast MAC advertisements, then the PE either forwards the
forwards the packet based on CE next-hop forwarding information packet based on CE next-hop forwarding information associated with
associated with the label or does a destination MAC address lookup to the label or does a destination MAC address lookup to forward the
forward the packet to a CE. packet to a CE.
15. Load Balancing of Unicast Frames 15. Load Balancing of Unicast Frames
This section specifies the load balancing procedures for sending This section specifies the load balancing procedures for sending
known unicast frames to a multi-homed CE. known unicast frames to a multi-homed CE.
15.1. Load balancing of traffic from an PE to remote CEs 15.1. Load balancing of traffic from an PE to remote CEs
Whenever a remote PE imports a MAC advertisement for a given <ESI, Whenever a remote PE imports a MAC advertisement for a given <ESI,
Ethernet Tag> in an EVI, it MUST examine all imported Ethernet A-D Ethernet Tag> in an EVI, it MUST examine all imported Ethernet A-D
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LAG interface (ES1), and is sending packets with MAC address MAC1 on LAG interface (ES1), and is sending packets with MAC address MAC1 on
VLAN1. A remote PE, say PE3, is able to learn that MAC1 is reachable VLAN1. A remote PE, say PE3, is able to learn that MAC1 is reachable
via PE1 and PE2. Both PE1 and PE2 may advertise MAC1 in BGP if they via PE1 and PE2. Both PE1 and PE2 may advertise MAC1 in BGP if they
receive packets with MAC1 from CE1. If this is not the case, and if receive packets with MAC1 from CE1. If this is not the case, and if
MAC1 is advertised only by PE1, PE3 still considers MAC1 as reachable MAC1 is advertised only by PE1, PE3 still considers MAC1 as reachable
via both PE1 and PE2 as both PE1 and PE2 advertise a Ethernet A-D via both PE1 and PE2 as both PE1 and PE2 advertise a Ethernet A-D
route per ESI for ES1 as well as an Ethernet A-D route per EVI for route per ESI for ES1 as well as an Ethernet A-D route per EVI for
<ES1, VLAN1>. <ES1, VLAN1>.
The MPLS label stack to send the packets to PE1 is the MPLS LSP stack The MPLS label stack to send the packets to PE1 is the MPLS LSP stack
to get to PE1 and the E-VPN label advertised by PE1 for CE1's MAC. to get to PE1 and the EVPN label advertised by PE1 for CE1's MAC.
The MPLS label stack to send packets to PE2 is the MPLS LSP stack to The MPLS label stack to send packets to PE2 is the MPLS LSP stack to
get to PE2 and the MPLS label in the Ethernet A-D route advertised by get to PE2 and the MPLS label in the Ethernet A-D route advertised by
PE2 for <ES1, VLAN1>, if PE2 has not advertised MAC1 in BGP. PE2 for <ES1, VLAN1>, if PE2 has not advertised MAC1 in BGP.
We will refer to these label stacks as MPLS next-hops. We will refer to these label stacks as MPLS next-hops.
The remote PE (PE3) can now load balance the traffic it receives from The remote PE (PE3) can now load balance the traffic it receives from
its CEs, destined for CE1, between PE1 and PE2. PE3 may use N-Tuple its CEs, destined for CE1, between PE1 and PE2. PE3 may use N-Tuple
flow information to hash traffic into one of the MPLS next-hops for flow information to hash traffic into one of the MPLS next-hops for
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to the CE is determined based on which of the two is the DF. to the CE is determined based on which of the two is the DF.
If the connectivity between the multi-homed CE and one of the PEs If the connectivity between the multi-homed CE and one of the PEs
that it is attached to fails, the PE MUST withdraw the Ethernet Tag that it is attached to fails, the PE MUST withdraw the Ethernet Tag
A-D routes, that had been previously advertised, for the Ethernet A-D routes, that had been previously advertised, for the Ethernet
Segment to the CE. When the MAC entry on the PE ages out, the PE MUST Segment to the CE. When the MAC entry on the PE ages out, the PE MUST
withdraw the MAC address from BGP. Note that to aid convergence, the withdraw the MAC address from BGP. Note that to aid convergence, the
Ethernet Tag A-D routes MAY be withdrawn before the MAC routes. This Ethernet Tag A-D routes MAY be withdrawn before the MAC routes. This
enables the remote PEs to remove the MPLS next-hop to this particular enables the remote PEs to remove the MPLS next-hop to this particular
PE from the set of MPLS next-hops that can be used to forward traffic PE from the set of MPLS next-hops that can be used to forward traffic
to the CE. For further details and procedures on withdrawal of E-VPN to the CE. For further details and procedures on withdrawal of EVPN
route types in the event of PE to CE failures please section "PE to route types in the event of PE to CE failures please section "PE to
CE Network Failures". CE Network Failures".
15.2. Load balancing of traffic between an PE and a local CE 15.2. Load balancing of traffic between an PE and a local CE
A CE may be configured with more than one interface connected to A CE may be configured with more than one interface connected to
different PEs or the same PE for load balancing, using a technology different PEs or the same PE for load balancing, using a technology
such as LAG. The PE(s) and the CE can load balance traffic onto these such as LAG. The PE(s) and the CE can load balance traffic onto these
interfaces using one of the following mechanisms. interfaces using one of the following mechanisms.
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multiple interfaces is dependent on the CE implementation. multiple interfaces is dependent on the CE implementation.
15.2.2. Control plane learning 15.2.2. Control plane learning
The CE can be a host that advertises the same MAC address using a The CE can be a host that advertises the same MAC address using a
control protocol on both interfaces. This enables the PE(s) to learn control protocol on both interfaces. This enables the PE(s) to learn
the host's MAC address and associate it with one or more interfaces. the host's MAC address and associate it with one or more interfaces.
The PEs can now load balance traffic destined to the host on the The PEs can now load balance traffic destined to the host on the
multiple interfaces. The host can also load balance the traffic it multiple interfaces. The host can also load balance the traffic it
generates onto these interfaces and the PE that receives the traffic generates onto these interfaces and the PE that receives the traffic
employs E-VPN forwarding procedures to forward the traffic. employs EVPN forwarding procedures to forward the traffic.
16. MAC Mobility 16. MAC Mobility
It is possible for a given host or end-station (as defined by its MAC It is possible for a given host or end-station (as defined by its MAC
address) to move from one Ethernet segment to another; this is address) to move from one Ethernet segment to another; this is
referred to as 'MAC Mobility' or 'MAC move' and it is different from referred to as 'MAC Mobility' or 'MAC move' and it is different from
the multi-homing situation in which a given MAC address is reachable the multi-homing situation in which a given MAC address is reachable
via multiple PEs for the same Ethernet segment. In a MAC move, there via multiple PEs for the same Ethernet segment. In a MAC move, there
would be two sets of MAC Advertisement routes, one set with the new would be two sets of MAC Advertisement routes, one set with the new
Ethernet segment and one set with the previous Ethernet segment, and Ethernet segment and one set with the previous Ethernet segment, and
the MAC address would appear to be reachable via each of these the MAC address would appear to be reachable via each of these
segments. segments.
In order to allow all of the PEs in the E-VPN to correctly determine In order to allow all of the PEs in the EVPN instance to correctly
the current location of the MAC address, all advertisements of it determine the current location of the MAC address, all advertisements
being reachable via the previous Ethernet segment MUST be withdrawn of it being reachable via the previous Ethernet segment MUST be
by the PEs, for the previous Ethernet segment, that had advertised withdrawn by the PEs, for the previous Ethernet segment, that had
it. advertised it.
If local learning is performed using the data plane, these PEs will If local learning is performed using the data plane, these PEs will
not be able to detect that the MAC address has moved to another not be able to detect that the MAC address has moved to another
Ethernet segment and the receipt of MAC Advertisement routes, with Ethernet segment and the receipt of MAC Advertisement routes, with
the MAC Mobility extended community attribute, from other PEs serves the MAC Mobility extended community attribute, from other PEs serves
as the trigger for these PEs to withdraw their advertisements. If as the trigger for these PEs to withdraw their advertisements. If
local learning is performed using the control or management planes, local learning is performed using the control or management planes,
these interactions serve as the trigger for these PEs to withdraw these interactions serve as the trigger for these PEs to withdraw
their advertisements. their advertisements.
In a situation where there are multiple moves of a given MAC, In a situation where there are multiple moves of a given MAC,
possibly between the same two Ethernet segments, there may be possibly between the same two Ethernet segments, there may be
multiple withdrawals and re-advertisements. In order to ensure that multiple withdrawals and re-advertisements. In order to ensure that
all PEs in the E-VPN receive all of these correctly through the all PEs in the EVPN instance receive all of these correctly through
intervening BGP infrastructure, it is necessary to introduce a the intervening BGP infrastructure, it is necessary to introduce a
sequence number into the MAC Mobility extended community attribute. sequence number into the MAC Mobility extended community attribute.
Since the sequence number is an unsigned 32 bit integer, all sequence An implementation MUST handle the scenarios where the sequence number
number comparisons must be performed modulo 2**32. This unsigned wraps around to process mobility event correctly.
arithmetic preserves the relationship of sequence numbers as they
cycle from 2**32 - 1 to 0.
Every MAC mobility event for a given MAC address will contain a Every MAC mobility event for a given MAC address will contain a
sequence number that is set using the following rules: sequence number that is set using the following rules:
- A PE advertising a MAC address for the first time advertises it - A PE advertising a MAC address for the first time advertises it
with no MAC Mobility extended community attribute. with no MAC Mobility extended community attribute.
- A PE detecting a locally attached MAC address for which it had - A PE detecting a locally attached MAC address for which it had
previously received a MAC Advertisement route with a different previously received a MAC Advertisement route with a different
Ethernet segment identifier advertises the MAC address in a MAC Ethernet segment identifier advertises the MAC address in a MAC
Advertisement route tagged with a MAC Mobility extended community Advertisement route tagged with a MAC Mobility extended community
attribute with a sequence number one greater than the sequence number attribute with a sequence number one greater than the sequence number
in the MAC mobility attribute of the received MAC Advertisement in the MAC mobility attribute of the received MAC Advertisement
route. In the case of the first mobility event for a given MAC route. In the case of the first mobility event for a given MAC
address, where the received MAC Advertisement route does not carry a address, where the received MAC Advertisement route does not carry a
MAC Mobility attribute, the value of the sequence number in the MAC Mobility attribute, the value of the sequence number in the
received route is assumed to be 0 for purpose of this processing. received route is assumed to be 0 for purpose of this processing.
- A PE detecting a locally attached MAC address for which it had - A PE detecting a locally attached MAC address for which it had
previously received a MAC Advertisement route with the same Ethernet previously received a MAC Advertisement route with the same non-zero
segment identifier advertises it with: Ethernet segment identifier advertises it with:
i. no MAC Mobility extended community attribute, if the received i. no MAC Mobility extended community attribute, if the received
route did not carry said attribute. route did not carry said attribute.
ii. a MAC Mobility extended community attribute with the sequence ii. a MAC Mobility extended community attribute with the sequence
number equal to the highest of the sequence number(s) in the number equal to the highest of the sequence number(s) in the
received MAC Advertisement route(s), if the received route(s) is received MAC Advertisement route(s), if the received route(s) is
(are) tagged with a MAC Mobility extended community attribute. (are) tagged with a MAC Mobility extended community attribute.
- A PE detecting a locally attached MAC address for which it had
previously received a MAC Advertisement route with the same zero
Ethernet segment identifier (single-homed scenarios) advertises it
with MAC mobility extended community attribute with the sequence
number set properly. In case of single-homed scenarios, there is no
need for ESI comparison. The reason ESI comparison is done for multi-
homing, is to prevent false detection of MAC move among the PEs
attached to the same multi-homed site.
A PE receiving a MAC Advertisement route for a MAC address with a A PE receiving a MAC Advertisement route for a MAC address with a
different Ethernet segment identifier and a higher sequence number different Ethernet segment identifier and a higher sequence number
than that which it had previously advertised, withdraws its MAC than that which it had previously advertised, withdraws its MAC
Advertisement route. If two (or more) PEs advertise the same MAC Advertisement route. If two (or more) PEs advertise the same MAC
address with same sequence number but different Ethernet segment address with same sequence number but different Ethernet segment
identifiers, a PE that receives these routes selects the route identifiers, a PE that receives these routes selects the route
advertised by the PE with lowest IP address as the best route. advertised by the PE with lowest IP address as the best route.
16.1. MAC Duplication Issue 16.1. MAC Duplication Issue
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important to recognize such situation and avoid incrementing the important to recognize such situation and avoid incrementing the
sequence number (in the MAC Mobility attribute) to infinity. In order sequence number (in the MAC Mobility attribute) to infinity. In order
to remedy such situation, a PE that detects a MAC mobility event by to remedy such situation, a PE that detects a MAC mobility event by
way of local learning starts an M-second timer (default value of M = way of local learning starts an M-second timer (default value of M =
5) and if it detects N MAC moves before the timer expires (default 5) and if it detects N MAC moves before the timer expires (default
value for N = 3), it concludes that a duplicate MAC situation has value for N = 3), it concludes that a duplicate MAC situation has
occurred. The PE MUST alert the operator and stop sending and occurred. The PE MUST alert the operator and stop sending and
processing any BGP MAC Advertisement routes for that MAC address till processing any BGP MAC Advertisement routes for that MAC address till
a corrective action is taken by the operator. The values of M and N a corrective action is taken by the operator. The values of M and N
MUST be configurable to allow for flexibility in operator control. MUST be configurable to allow for flexibility in operator control.
Note that the other PEs in the E-VPN instance will forward the
traffic for the duplicate MAC address to one of the PEs advertising
the duplicate MAC address.
17. Multicast 16.2. Sticky MAC addresses
The PEs in a particular E-VPN may use ingress replication or P2MP There are scenarios in which it is desired to configure some MAC
LSPs to send multicast traffic to other PEs. addresses as static so that they are not subjected to MAC move. In
such scenarios, these MAC addresses are advertised with MAC Mobility
Extended Community where static flag is set to 1 and sequence number
is set to zero. If a PE receives such advertisements and later learns
the same MAC address(es) via local learning, then the PE MUST alert
the operator.
17. Multicast & Broadcast
The PEs in a particular EVPN instance may use ingress replication or
P2MP LSPs to send multicast traffic to other PEs.
17.1. Ingress Replication 17.1. Ingress Replication
The PEs may use ingress replication for flooding unknown unicast, The PEs may use ingress replication for flooding BUM traffic as
multicast or broadcast traffic as described in section "Handling of described in section "Handling of Multi-Destination Traffic". A given
Multi-Destination Traffic". A given unknown unicast or broadcast broadcast packet must be sent to all the remote PEs. However a given
packet must be sent to all the remote PEs. However a given multicast multicast packet for a multicast flow may be sent to only a subset of
packet for a multicast flow may be sent to only a subset of the PEs. the PEs. Specifically a given multicast flow may be sent to only
Specifically a given multicast flow may be sent to only those PEs those PEs that have receivers that are interested in the multicast
that have receivers that are interested in the multicast flow. flow. Determining which of the PEs have receivers for a given
Determining which of the PEs have receivers for a given multicast multicast flow is done using explicit tracking described below.
flow is done using explicit tracking described below.
17.2. P2MP LSPs 17.2. P2MP LSPs
An PE may use an "Inclusive" tree for sending an unknown unicast, An PE may use an "Inclusive" tree for sending an BUM packet. This
broadcast or multicast packet or a "Selective" tree. This terminology terminology is borrowed from [VPLS-MCAST].
is borrowed from [VPLS-MCAST].
A variety of transport technologies may be used in the SP network. A variety of transport technologies may be used in the SP network.
For inclusive P-Multicast trees, these transport technologies include For inclusive P-Multicast trees, these transport technologies include
point-to-multipoint LSPs created by RSVP-TE or mLDP. For selective P- point-to-multipoint LSPs created by RSVP-TE or mLDP.
Multicast trees, only unicast PE-PE tunnels (using MPLS or IP/GRE
encapsulation) and P2MP LSPs are supported, and the supported P2MP
LSP signaling protocols are RSVP-TE, and mLDP.
17.3. MP2MP LSPs
The root of the MP2MP LDP LSP advertises the Inclusive Multicast Tag
route with the PMSI Tunnel attribute set to the MP2MP Tunnel
identifier. This advertisement is then sent to all PEs in the E-VPN.
Upon receiving the Inclusive Multicast Tag routes with a PMSI Tunnel
attribute that contains the MP2MP Tunnel identifier, the receiving
PEs initiate the setup of the MP2MP tunnel towards the root using the
procedures in [MLDP].
17.3.1. Inclusive Trees 17.2.1. Inclusive Trees
An Inclusive Tree allows the use of a single multicast distribution An Inclusive Tree allows the use of a single multicast distribution
tree, referred to as an Inclusive P-Multicast tree, in the SP network tree, referred to as an Inclusive P-Multicast tree, in the SP network
to carry all the multicast traffic from a specified set of EVIs on a to carry all the multicast traffic from a specified set of EVPN
given PE. A particular P-Multicast tree can be set up to carry the instances on a given PE. A particular P-Multicast tree can be set up
traffic originated by sites belonging to a single E-VPN, or to carry to carry the traffic originated by sites belonging to a single EVPN
the traffic originated by sites belonging to different E-VPNs. The instance, or to carry the traffic originated by sites belonging to
ability to carry the traffic of more than one E-VPN on the same tree different EVPN instances. The ability to carry the traffic of more
is termed 'Aggregation'. The tree needs to include every PE that is a than one EVPN instance on the same tree is termed 'Aggregation'. The
member of any of the E-VPNs that are using the tree. This implies tree needs to include every PE that is a member of any of the EVPN
that an PE may receive multicast traffic for a multicast stream even instances that are using the tree. This implies that an PE may
if it doesn't have any receivers that are interested in receiving receive multicast traffic for a multicast stream even if it doesn't
traffic for that stream. have any receivers that are interested in receiving traffic for that
stream.
An Inclusive P-Multicast tree as defined in this document is a P2MP An Inclusive P-Multicast tree as defined in this document is a P2MP
tree. A P2MP tree is used to carry traffic only for E-VPN CEs that tree. A P2MP tree is used to carry traffic only for EVPN CEs that
are connected to the PE that is the root of the tree. are connected to the PE that is the root of the tree.
The procedures for signaling an Inclusive Tree are the same as those The procedures for signaling an Inclusive Tree are the same as those
in [VPLS-MCAST] with the VPLS-AD route replaced with the Inclusive in [VPLS-MCAST] with the VPLS-AD route replaced with the Inclusive
Multicast Ethernet Tag route. The P-Tunnel attribute [VPLS-MCAST] for Multicast Ethernet Tag route. The P-Tunnel attribute [VPLS-MCAST] for
an Inclusive tree is advertised in the Inclusive Multicast route as an Inclusive tree is advertised in the Inclusive Multicast route as
described in section "Handling of Multi-Destination Traffic". Note described in section "Handling of Multi-Destination Traffic". Note
that an PE can "aggregate" multiple inclusive trees for different that an PE can "aggregate" multiple inclusive trees for different
EVIs on the same P2MP LSP using upstream labels. The procedures for EVPN instances on the same P2MP LSP using upstream labels. The
aggregation are the same as those described in [VPLS-MCAST], with procedures for aggregation are the same as those described in [VPLS-
VPLS A-D routes replaced by E-VPN Inclusive Multicast routes. MCAST], with VPLS A-D routes replaced by EVPN Inclusive Multicast
routes.
17.3.2. Selective Trees
A Selective P-Multicast tree is used by an PE to send IP multicast
traffic for one or more specific IP multicast streams, originated by
CEs connected to the PE, that belong to the same or different E-VPNs,
to a subset of the PEs that belong to those E-VPNs. Each of the PEs
in the subset should be on the path to a receiver of one or more
multicast streams that are mapped onto the tree. The ability to use
the same tree for multicast streams that belong to different E-VPNs
is termed an PE the ability to create separate SP multicast trees for
specific multicast streams, e.g. high bandwidth multicast streams.
This allows traffic for these multicast streams to reach only those
PE routers that have receivers in these streams. This avoids flooding
other PE routers in the E-VPN.
An SP can use both Inclusive P-Multicast trees and Selective P-
Multicast trees or either of them for a given E-VPN on an PE, based
on local configuration.
The granularity of a selective tree is <RD, PE, S, G> where S is an
IP multicast source address and G is an IP multicast group address or
G is a multicast MAC address. Wildcard sources and wildcard groups
are supported. Selective trees require explicit tracking as described
below.
A E-VPN PE advertises a selective tree using a E-VPN selective A-D
route. The procedures are the same as those in [VPLS-MCAST] with S-
PMSI A-D routes in [VPLS-MCAST] replaced by E-VPN Selective A-D
routes. The information elements of the E-VPN selective A-D route
are similar to those of the VPLS S-PMSI A-D route with the following
differences. A E-VPN Selective A-D route includes an optional
Ethernet Tag field. Also an E-VPN selective A-D route may encode a
MAC address in the Group field. The encoding details of the E-VPN
selective A-D route will be described in the next revision.
Selective trees can also be aggregated on the same P2MP LSP using
aggregation as described in [VPLS-MCAST].
17.4. Explicit Tracking
[VPLS-MCAST] describes procedures for explicit tracking that rely on
Leaf A-D routes. The same procedures are used for explicit tracking
in this specification with VPLS Leaf A-D routes replaced with E-VPN
Leaf A-D routes. These procedures allow a root PE to request
multicast membership information for a given (S, G), from leaf PEs.
Leaf PEs rely on IGMP snooping or PIM snooping between the PE and the
CE to determine the multicast membership information. Note that the
procedures in [VPLS-MCAST] do not describe how explicit tracking is
performed if the CEs are enabled with join suppression. The
procedures for this case will be described in a future version.
18. Convergence 18. Convergence
This section describes failure recovery from different types of This section describes failure recovery from different types of
network failures. network failures.
18.1. Transit Link and Node Failures between PEs 18.1. Transit Link and Node Failures between PEs
The use of existing MPLS Fast-Reroute mechanisms can provide failure The use of existing MPLS Fast-Reroute mechanisms can provide failure
recovery in the order of 50ms, in the event of transit link and node recovery in the order of 50ms, in the event of transit link and node
failures in the infrastructure that connects the PEs. failures in the infrastructure that connects the PEs.
18.2. PE Failures 18.2. PE Failures
Consider a host host1 that is dual homed to PE1 and PE2. If PE1 Consider a host host1 that is dual homed to PE1 and PE2. If PE1
fails, a remote PE, PE3, can discover this based on the failure of fails, a remote PE, PE3, can discover this based on the failure of
the BGP session. This failure detection can be in the sub-second the BGP session. This failure detection can be in the sub-second
range if BFD is used to detect BGP session failure. PE3 can update range if BFD is used to detect BGP session failure. PE3 can update
skipping to change at page 42, line 46 skipping to change at page 43, line 20
Consider a host host1 that is dual homed to PE1 and PE2. If PE1 Consider a host host1 that is dual homed to PE1 and PE2. If PE1
fails, a remote PE, PE3, can discover this based on the failure of fails, a remote PE, PE3, can discover this based on the failure of
the BGP session. This failure detection can be in the sub-second the BGP session. This failure detection can be in the sub-second
range if BFD is used to detect BGP session failure. PE3 can update range if BFD is used to detect BGP session failure. PE3 can update
its forwarding state to start sending all traffic for host1 to only its forwarding state to start sending all traffic for host1 to only
PE2. It is to be noted that this failure recovery is potentially PE2. It is to be noted that this failure recovery is potentially
faster than what would be possible if data plane learning were to be faster than what would be possible if data plane learning were to be
used. As in that case PE3 would have to rely on re-learning of MAC used. As in that case PE3 would have to rely on re-learning of MAC
addresses via PE2. addresses via PE2.
18.2.1. Local Repair 18.2. PE to CE Network Failures
It is possible to perform local repair in the case of PE failures.
Details will be specified in the future.
18.3. PE to CE Network Failures
When an Ethernet segment connected to an PE fails or when a Ethernet When an Ethernet segment connected to an PE fails or when a Ethernet
Tag is decommissioned on an Ethernet segment, then the PE MUST Tag is decommissioned on an Ethernet segment, then the PE MUST
withdraw the Ethernet A-D route(s) announced for the <ESI, Ethernet withdraw the Ethernet A-D route(s) announced for the <ESI, Ethernet
Tags> that are impacted by the failure or decommissioning. In Tags> that are impacted by the failure or decommissioning. In
addition, the PE MUST also withdraw the MAC advertisement routes that addition, the PE MUST also withdraw the MAC advertisement routes that
are impacted by the failure or decommissioning. are impacted by the failure or decommissioning.
The Ethernet A-D routes should be used by an implementation to The Ethernet A-D routes should be used by an implementation to
optimize the withdrawal of MAC advertisement routes. When an PE optimize the withdrawal of MAC advertisement routes. When an PE
receives a withdrawal of a particular Ethernet A-D route from an PE receives a withdrawal of a particular Ethernet A-D route from an PE
it SHOULD consider all the MAC advertisement routes, that are learned it SHOULD consider all the MAC advertisement routes, that are learned
from the same <ESI, Ethernet Tag> as in the Ethernet A-D route, from from the same <ESI, Ethernet Tag> as in the Ethernet A-D route, from
the advertising PE, as having been withdrawn. This optimizes the the advertising PE, as having been withdrawn. This optimizes the
network convergence times in the event of PE to CE failures. network convergence times in the event of PE to CE failures.
19. LACP State Synchronization 19. Frame Ordering
This section requires review and discussion amongst the authors and
will be revised in the next version.
To support CE multi-homing with multi-chassis Ethernet bundles, the
PEs connected to a given CE should synchronize [802.1AX] LACP state
amongst each other. This ensures that the PEs can present a single
LACP bundle to the CE. This is required for initial system bring-up
and upon any configuration change.
This includes at least the following LACP specific configuration In a MAC address, bit-1 of the most significant byte is used for
parameters: unicast/multicast indication and bit-2 is used for globally unique
versus locally administered MAC address. If the value of the 2nd
nibble (bits 4 thorough 8) of the most significant byte of the
destination MAC address (which follows the last MPLS label) happens
to be 0x4 or 0x6, then the Ethernet frame can be misinterpreted as an
IPv4 or IPv6 packet by intermediate P nodes performing ECMP resulting
in load balancing packets belonging to the same flow on different
ECMP paths, thus subjecting them to different delays. Therefore,
packets belonging to the same flow can arrive at the destination out
of order. This out of order delivery can happen during steady state
in absence of any failures resulting in significant impact to the
network operation.
- System Identifier (MAC Address): uniquely identifies a LACP In order to avoid any such mis-ordering, the usage of control word
speaker. SHALL adhere to the following rules:
- System Priority: determines which LACP speaker's port
priorities are used in the Selection logic.
- Aggregator Identifier: uniquely identifies a bundle within
a LACP speaker.
- Aggregator MAC Address: identifies the MAC address of the
bundle.
- Aggregator Key: used to determine which ports can join an
Aggregator.
- Port Number: uniquely identifies an interface within a LACP
speaker.
- Port Key: determines the set of ports that can be bundled.
- Port Priority: determines a port's precedence level to join
a bundle in case the number of eligible ports exceeds the
maximum number of links allowed in a bundle.
Furthermore, the PEs should also synchronize operational (run-time) - A PE MUST use the control world when sending EVPN encapsulated
data, in order for the LACP Selection logic state-machines to packets over a MP2P or a P2P LSP
execute. This operational data includes the following LACP
operational parameters, on a per port basis:
- Partner System Identifier: this is the CE System MAC address. - A PE MUST NOT use the control world when sending EVPN encapsulated
- Partner System Priority: the CE LACP System Priority packets over a P2MP LSP
- Partner Port Number: CE's AC port number.
- Partner Port Priority: CE's AC Port Priority.
- Partner Key: CE's key for this AC.
- Partner State: CE's LACP State for the AC.
- Actor State: PE's LACP State for the AC.
- Port State: PE's AC port status.
The above state needs to be communicated between PEs forming a multi- The control word is defined as follows:
chassis bundle during LACP initial bringup, upon any configuration
change and upon the occurrence of a failure.
It should be noted that the above configuration and operational state 0 1 2 3
is localized in scope and is only relevant to PEs which connect to 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
the same multi-homed CE over a given Ethernet bundle. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0| Reserved | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Furthermore, the communication of state changes, upon failures, must In the above diagram the first 4 bits MUST be set to 0. The rest of
occur with minimal latency, in order to minimize the switchover time the first 16 bits are reserved for future use. They MUST be set to 0
and consequent service disruption. The protocol details for when transmitting, and MUST be ignored upon receipt. The next 16 bits
synchronizing the LACP state will be described in the following provide a sequence number that MUST also be set to zero by default.
version.
20. Acknowledgements 20. Acknowledgements
We would like to thank Yakov Rekhter, Pedro Marques, Kaushik Ghosh, Special thanks to Yakov Rekhter for reviewing this draft several
times and providing valuable comments and for his very engaging
discussions on several topics of this draft that helped shape this
document. We would also like to thank Pedro Marques, Kaushik Ghosh,
Nischal Sheth, Robert Raszuk, Amit Shukla and Nadeem Mohammed for Nischal Sheth, Robert Raszuk, Amit Shukla and Nadeem Mohammed for
discussions that helped shape this document. We would also like to discussions that helped shape this document. We would also like to
thank Han Nguyen for his comments and support of this work. We would thank Han Nguyen for his comments and support of this work. We would
also like to thank Steve Kensil and Reshad Rahman for their reviews. also like to thank Steve Kensil and Reshad Rahman for their reviews.
Last but not least, many thanks to Jakob Heitz for his help to Last but not least, many thanks to Jakob Heitz for his help to
improve several sections of this draft. improve several sections of this draft.
21. Security Considerations 21. Security Considerations
22. IANA Considerations 22. IANA Considerations
skipping to change at page 45, line 27 skipping to change at page 45, line 30
[RFC4760] T. Bates et. al., "Multiprotocol Extensions for BGP-4", RFC [RFC4760] T. Bates et. al., "Multiprotocol Extensions for BGP-4", RFC
4760, January 2007 4760, January 2007
23.2 Informative References 23.2 Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[EVPN-REQ] A. Sajassi, R. Aggarwal et. al., "Requirements for [EVPN-REQ] A. Sajassi, R. Aggarwal et. al., "Requirements for
Ethernet VPN", draft-ietf-l2vpn-evpn-req-01.txt Ethernet VPN", draft-ietf-l2vpn-evpn-req-04.txt, July
2013.
[VPLS-MCAST] "Multicast in VPLS". R. Aggarwal et.al., draft-ietf- [VPLS-MCAST] "Multicast in VPLS". R. Aggarwal et.al., draft-ietf-
l2vpn-vpls-mcast-11.txt l2vpn-vpls-mcast-14.txt, July 2013.
[RT-CONSTRAIN] P. Marques et. al., "Constrained Route Distribution [RT-CONSTRAIN] P. Marques et. al., "Constrained Route Distribution
for Border Gateway Protocol/MultiProtocol Label Switching for Border Gateway Protocol/MultiProtocol Label Switching
(BGP/MPLS) Internet Protocol (IP) Virtual Private Networks (BGP/MPLS) Internet Protocol (IP) Virtual Private Networks
(VPNs)", RFC 4684, November 2006 (VPNs)", RFC 4684, November 2006
[BGP-VPLS-MH] "BGP based Multi-homing in Virtual Private LAN
Service", K. Kompella et. al., draft-ietf-l2vpn-vpls-
multihoming-04.txt
24. Author's Address 24. Author's Address
Ali Sajassi Ali Sajassi
Cisco Cisco
Email: sajassi@cisco.com Email: sajassi@cisco.com
Rahul Aggarwal Rahul Aggarwal
Email: raggarwa_1@yahoo.com Email: raggarwa_1@yahoo.com
Wim Henderickx Wim Henderickx
Alcatel-Lucent Alcatel-Lucent
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