draft-ietf-l2vpn-evpn-04.txt   draft-ietf-l2vpn-evpn-05.txt 
Network Working Group A. Sajassi Network Working Group A. Sajassi
INTERNET-DRAFT Cisco INTERNET-DRAFT Cisco
Category: Standards Track Category: Standards Track
R. Aggarwal R. Aggarwal
N. Bitar Arktan N. Bitar Arktan
Verizon Verizon
W. Henderickx W. Henderickx
S. Boutros F. Balus J. Drake Alcatel-Lucent
K. Patel Alcatel-Lucent Juniper Networks
S. Salam Aldrin Isaac
Cisco Aldrin Isaac
Bloomberg Bloomberg
J. Drake
R. Shekhar J. Uttaro
Juniper Networks AT&T
Expires: January 15, 2014 July 15, 2013 J. Uttaro
AT&T
Expires: August 12, 2014 February 12, 2014
BGP MPLS Based Ethernet VPN BGP MPLS Based Ethernet VPN
draft-ietf-l2vpn-evpn-04 draft-ietf-l2vpn-evpn-05
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as other groups may also distribute working documents as
Internet-Drafts. Internet-Drafts.
skipping to change at page 2, line 25 skipping to change at page 2, line 25
Abstract Abstract
This document describes procedures for BGP MPLS based Ethernet VPNs This document describes procedures for BGP MPLS based Ethernet VPNs
(EVPN). (EVPN).
Table of Contents Table of Contents
1. Specification of requirements . . . . . . . . . . . . . . . . . 5 1. Specification of requirements . . . . . . . . . . . . . . . . . 5
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 6 4. BGP MPLS Based EVPN Overview . . . . . . . . . . . . . . . . . 6
5. BGP MPLS Based EVPN Overview . . . . . . . . . . . . . . . . . 6 5. Ethernet Segment . . . . . . . . . . . . . . . . . . . . . . . 7
6. Ethernet Segment . . . . . . . . . . . . . . . . . . . . . . . 7 6. Ethernet Tag . . . . . . . . . . . . . . . . . . . . . . . . . 10
7. Ethernet Tag . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.1 VLAN Based Service Interface . . . . . . . . . . . . . . . . 10
7.1 VLAN Based Service Interface . . . . . . . . . . . . . . . . 9 6.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 11
7.2 VLAN Bundle Service Interface . . . . . . . . . . . . . . . 9 6.2.1 Port Based Service Interface . . . . . . . . . . . . . . 11
7.2.1 Port Based Service Interface . . . . . . . . . . . . . . 10 6.3 VLAN Aware Bundle Service Interface . . . . . . . . . . . . 11
7.3 VLAN Aware Bundle Service Interface . . . . . . . . . . . . 10 6.3.1 Port Based VLAN Aware Service Interface . . . . . . . . 11
7.3.1 Port Based VLAN Aware Service Interface . . . . . . . . 10 7. BGP EVPN NLRI . . . . . . . . . . . . . . . . . . . . . . . . . 12
8. BGP EVPN NLRI . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Ethernet Auto-Discovery Route . . . . . . . . . . . . . . . 12
8.1. Ethernet Auto-Discovery Route . . . . . . . . . . . . . . . 11 7.2. MAC/IP Advertisement Route . . . . . . . . . . . . . . . . 13
8.2. MAC Advertisement Route . . . . . . . . . . . . . . . . . 12 7.3. Inclusive Multicast Ethernet Tag Route . . . . . . . . . . 14
8.3. Inclusive Multicast Ethernet Tag Route . . . . . . . . . . 12 7.4 Ethernet Segment Route . . . . . . . . . . . . . . . . . . . 14
8.4 Ethernet Segment Route . . . . . . . . . . . . . . . . . . . 13 7.5 ESI Label Extended Community . . . . . . . . . . . . . . . . 15
8.5 ESI Label Extended Community . . . . . . . . . . . . . . . . 13 7.6 ES-Import Route Target . . . . . . . . . . . . . . . . . . . 15
8.6 ES-Import Route Target . . . . . . . . . . . . . . . . . . . 14 7.7 MAC Mobility Extended Community . . . . . . . . . . . . . . 16
8.7 MAC Mobility Extended Community . . . . . . . . . . . . . . 14 7.8 Default Gateway Extended Community . . . . . . . . . . . . . 16
8.8 Default Gateway Extended Community . . . . . . . . . . . . . 15 8. Multi-homing Functions . . . . . . . . . . . . . . . . . . . . 16
9. Multi-homing Functions . . . . . . . . . . . . . . . . . . . . 15 8.1 Multi-homed Ethernet Segment Auto-Discovery . . . . . . . . 17
9.1 Multi-homed Ethernet Segment Auto-Discovery . . . . . . . . 15 8.1.1 Constructing the Ethernet Segment Route . . . . . . . . 17
9.1.1 Constructing the Ethernet Segment Route . . . . . . . . 15 8.2 Fast Convergence . . . . . . . . . . . . . . . . . . . . . . 17
9.2 Fast Convergence . . . . . . . . . . . . . . . . . . . . . . 16 8.2.1 Constructing the Ethernet A-D per Ethernet Segment
9.2.1 Constructing the Ethernet A-D Route per Ethernet (ES) Route . . . . . . . . . . . . . . . . . . . . . . . 18
Segment . . . . . . . . . . . . . . . . . . . . . . . . 16 8.2.1.1. Ethernet A-D Route Targets . . . . . . . . . . . . 18
9.2.1.1. Ethernet A-D Route Targets . . . . . . . . . . . . 17 8.3 Split Horizon . . . . . . . . . . . . . . . . . . . . . . . 19
9.3 Split Horizon . . . . . . . . . . . . . . . . . . . . . . . 17 8.3.1 ESI Label Assignment . . . . . . . . . . . . . . . . . . 19
9.3.1 ESI Label Assignment . . . . . . . . . . . . . . . . . . 18 8.3.1.1 Ingress Replication . . . . . . . . . . . . . . . . 19
9.3.1.1 Ingress Replication . . . . . . . . . . . . . . . . 18 8.3.1.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . 20
9.3.1.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . 19
9.4 Aliasing and Backup-Path . . . . . . . . . . . . . . . . . . 20 8.4 Aliasing and Backup-Path . . . . . . . . . . . . . . . . . . 21
9.4.1 Constructing the Ethernet A-D Route per EVI . . . . . . 21 8.4.1 Constructing the Ethernet A-D per EVPN Instance (EVI)
9.4.1.1 Ethernet A-D Route Targets . . . . . . . . . . . . . 22 Route . . . . . . . . . . . . . . . . . . . . . . . . . 22
9.5 Designated Forwarder Election . . . . . . . . . . . . . . . 22 8.4.1.1 Ethernet A-D Route Targets . . . . . . . . . . . . . 23
9.6. Interoperability with Single-homing PEs . . . . . . . . . . 24 8.5 Designated Forwarder Election . . . . . . . . . . . . . . . 23
10. Determining Reachability to Unicast MAC Addresses . . . . . . 25 8.6. Interoperability with Single-homing PEs . . . . . . . . . . 25
10.1. Local Learning . . . . . . . . . . . . . . . . . . . . . . 25 9. Determining Reachability to Unicast MAC Addresses . . . . . . . 26
10.2. Remote learning . . . . . . . . . . . . . . . . . . . . . 26 9.1. Local Learning . . . . . . . . . . . . . . . . . . . . . . 26
10.2.1. Constructing the BGP EVPN MAC Address Advertisement . 26 9.2. Remote learning . . . . . . . . . . . . . . . . . . . . . . 27
10.2.2 Route Resolution . . . . . . . . . . . . . . . . . . . 28 9.2.1. Constructing the BGP EVPN MAC/IP Address
11. ARP and ND . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Advertisement . . . . . . . . . . . . . . . . . . . . . 27
11.1 Default Gateway . . . . . . . . . . . . . . . . . . . . . . 29 9.2.2 Route Resolution . . . . . . . . . . . . . . . . . . . . 29
12. Handling of Multi-Destination Traffic . . . . . . . . . . . . 30 10. ARP and ND . . . . . . . . . . . . . . . . . . . . . . . . . . 30
12.1. Construction of the Inclusive Multicast Ethernet Tag 10.1 Default Gateway . . . . . . . . . . . . . . . . . . . . . . 30
Route . . . . . . . . . . . . . . . . . . . . . . . . . . 31 11. Handling of Multi-Destination Traffic . . . . . . . . . . . . 32
12.2. P-Tunnel Identification . . . . . . . . . . . . . . . . . 31 11.1. Construction of the Inclusive Multicast Ethernet Tag
13. Processing of Unknown Unicast Packets . . . . . . . . . . . . 32 Route . . . . . . . . . . . . . . . . . . . . . . . . . . 32
13.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 33 11.2. P-Tunnel Identification . . . . . . . . . . . . . . . . . 32
13.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . . . . . 33 12. Processing of Unknown Unicast Packets . . . . . . . . . . . . 33
14. Forwarding Unicast Packets . . . . . . . . . . . . . . . . . . 34 12.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 34
14.1. Forwarding packets received from a CE . . . . . . . . . . 34 12.2. P2MP MPLS LSPs . . . . . . . . . . . . . . . . . . . . . . 34
14.2. Forwarding packets received from a remote PE . . . . . . . 35 13. Forwarding Unicast Packets . . . . . . . . . . . . . . . . . . 35
14.2.1. Unknown Unicast Forwarding . . . . . . . . . . . . . . 35 13.1. Forwarding packets received from a CE . . . . . . . . . . 35
14.2.2. Known Unicast Forwarding . . . . . . . . . . . . . . . 35 13.2. Forwarding packets received from a remote PE . . . . . . . 36
15. Load Balancing of Unicast Frames . . . . . . . . . . . . . . . 36 13.2.1. Unknown Unicast Forwarding . . . . . . . . . . . . . . 36
15.1. Load balancing of traffic from an PE to remote CEs . . . . 36 13.2.2. Known Unicast Forwarding . . . . . . . . . . . . . . . 36
15.1.1 Single-Active Redundancy Mode . . . . . . . . . . . . . 36 14. Load Balancing of Unicast Frames . . . . . . . . . . . . . . . 37
15.1.2 All-Active Redundancy Mode . . . . . . . . . . . . . . 37 14.1. Load balancing of traffic from an PE to remote CEs . . . . 37
15.2. Load balancing of traffic between an PE and a local CE . . 38 14.1.1 Single-Active Redundancy Mode . . . . . . . . . . . . . 37
15.2.1. Data plane learning . . . . . . . . . . . . . . . . . 38 14.1.2 All-Active Redundancy Mode . . . . . . . . . . . . . . 38
15.2.2. Control plane learning . . . . . . . . . . . . . . . . 39 14.2. Load balancing of traffic between an PE and a local CE . . 39
16. MAC Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 39 14.2.1. Data plane learning . . . . . . . . . . . . . . . . . 40
16.1. MAC Duplication Issue . . . . . . . . . . . . . . . . . . 41 14.2.2. Control plane learning . . . . . . . . . . . . . . . . 40
16.2. Sticky MAC addresses . . . . . . . . . . . . . . . . . . . 41 15. MAC Mobility . . . . . . . . . . . . . . . . . . . . . . . . . 40
17. Multicast & Broadcast . . . . . . . . . . . . . . . . . . . . 41 15.1. MAC Duplication Issue . . . . . . . . . . . . . . . . . . 42
17.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 41 15.2. Sticky MAC addresses . . . . . . . . . . . . . . . . . . . 42
17.2. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 42 16. Multicast & Broadcast . . . . . . . . . . . . . . . . . . . . 42
17.2.1. Inclusive Trees . . . . . . . . . . . . . . . . . . . 42 16.1. Ingress Replication . . . . . . . . . . . . . . . . . . . 43
18. Convergence . . . . . . . . . . . . . . . . . . . . . . . . . 42 16.2. P2MP LSPs . . . . . . . . . . . . . . . . . . . . . . . . 43
18.1. Transit Link and Node Failures between PEs . . . . . . . . 42 16.2.1. Inclusive Trees . . . . . . . . . . . . . . . . . . . 43
18.2. PE Failures . . . . . . . . . . . . . . . . . . . . . . . 43 17. Convergence . . . . . . . . . . . . . . . . . . . . . . . . . 44
18.2. PE to CE Network Failures . . . . . . . . . . . . . . . . 43 17.1. Transit Link and Node Failures between PEs . . . . . . . . 44
19. Frame Ordering . . . . . . . . . . . . . . . . . . . . . . . . 43 17.2. PE Failures . . . . . . . . . . . . . . . . . . . . . . . 44
20. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 44 17.3. PE to CE Network Failures . . . . . . . . . . . . . . . . 44
21. Security Considerations . . . . . . . . . . . . . . . . . . . 44 18. Frame Ordering . . . . . . . . . . . . . . . . . . . . . . . . 45
22. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 44 19. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 45
23. References . . . . . . . . . . . . . . . . . . . . . . . . . . 45 20. Security Considerations . . . . . . . . . . . . . . . . . . . 46
23.1 Normative References . . . . . . . . . . . . . . . . . . . 45 21. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 47
23.2 Informative References . . . . . . . . . . . . . . . . . . 45 22. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47
24. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 45 23. References . . . . . . . . . . . . . . . . . . . . . . . . . . 47
23.1 Normative References . . . . . . . . . . . . . . . . . . . 48
23.2 Informative References . . . . . . . . . . . . . . . . . . 48
24. Author's Address . . . . . . . . . . . . . . . . . . . . . . . 48
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. Terminology 2. Terminology
Bridge Domain: Bridge Domain:
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corresponding Ethernet tag. corresponding Ethernet tag.
LACP: Link Aggregation Control Protocol LACP: Link Aggregation Control Protocol
MP2MP: Multipoint to Multipoint MP2MP: Multipoint to Multipoint
P2MP: Point to Multipoint P2MP: Point to Multipoint
P2P: Point to Point P2P: Point to Point
Single-Active Mode: When a device or a network is multi-homed to two Single-Active Redundancy Mode: When only a single PE, among a group
or more PEs and when only a single PE in such redundancy group can of PEs attached to an Ethernet segment, is allowed to forward traffic
forward traffic to/from the multi-homed device or network for a given to/from that Ethernet Segment, then the Ethernet segment is defined
VLAN, then such multi-homing or redundancy is referred to as "Single- to be operating in Single-Active redundancy mode.
Active".
All-Active Mode: When a device is multi-homed to two or more PEs and All-Active Redundancy Mode: When all PEs attached to an Ethernet
when all PEs in such redundancy group can forward traffic to/from the segment are allowed to forward traffic to/from that Ethernet Segment,
multi-homed device for a given VLAN, then such multi-homing or then the Ethernet segment is defined to be operating in All-Active
redundancy is referred to as "All-Active". redundancy mode.
3. Introduction 3. Introduction
This document describes procedures for BGP MPLS based Ethernet VPNs This document describes procedures for BGP MPLS based Ethernet VPNs
(EVPN). The procedures described here are intended to meet the (EVPN). The procedures described here are intended to meet the
requirements specified in [EVPN-REQ]. Please refer to [EVPN-REQ] for requirements specified in [EVPN-REQ]. Please refer to [EVPN-REQ] for
the detailed requirements and motivation. EVPN requires extensions to the detailed requirements and motivation. EVPN requires extensions to
existing IP/MPLS protocols as described in this document. In addition existing IP/MPLS protocols as described in this document. In addition
to these extensions EVPN uses several building blocks from existing to these extensions EVPN uses several building blocks from existing
MPLS technologies. MPLS technologies.
4. Contributors 4. BGP MPLS Based EVPN Overview
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 This section provides an overview of EVPN. An EVPN instance comprises
CEs that are connected to PEs that form the edge of the MPLS 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 infrastructure. A CE may be a host, a router or a switch. The PEs
provide virtual Layer 2 bridged connectivity between the CEs. There provide virtual Layer 2 bridged connectivity between the CEs. There
may be multiple EVPN instances in the provider's network. 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
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EVPN instance requires a Route-Distinguisher (RD) which is unique per EVPN instance requires a Route-Distinguisher (RD) which is unique per
PE and one or more globally unique Route-Targets (RTs). A CE attaches PE and one or more globally unique Route-Targets (RTs). A CE attaches
to a MAC-VRF on an PE, on an Ethernet interface which may be to a MAC-VRF on an PE, on an Ethernet interface which may be
configured for one or more Ethernet Tags, e.g., VLAN IDs. Some configured for one or more Ethernet Tags, e.g., VLAN IDs. Some
deployment scenarios guarantee uniqueness of VLAN IDs across EVPN deployment scenarios guarantee uniqueness of VLAN IDs across EVPN
instances: all points of attachment for a given EVPN instance use the instances: all points of attachment for a given EVPN instance use the
same VLAN ID, and no other EVPN instance uses this VLAN ID. This 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 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 5. 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 EVPN instances on all the PEs). unique network wide (e.g., across all EVPN instances on all the PEs).
If the 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 guaranteed; 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.
ESI can be assigned using various mechanisms:
1. If IEEE 802.1AX LACP is used between the PEs and CEs, then In a network with managed and not-managed CEs, the ESI has the
the ESI is determined from LACP by concatenating the following following format:
parameters:
+ CE LACP System Identifier comprised of two octets of System +---+---+---+---+---+---+---+---+---+---+
Priority and six octets of System MAC address, where the | T | ESI Value |
System Priority is encoded in the most significant two octets. +---+---+---+---+---+---+---+---+---+---+
The CE LACP identifier MUST be encoded in the high order eight
octets of the ESI.
+ CE LACP two octets Port Key. The CE LACP port key MUST be Where:
encoded in the low order two octets of the ESI.
As far as the CE is concerned, it would treat the multiple PEs T (ESI Type) is a 1-byte field (most significant octet) that
that it is connected to as the same switch. This allows the CE specifies the format of the remaining nine bytes (ESI Value). The
to aggregate links that are attached to different PEs in the following 6 ESI types can be used:
same bundle.
This mechanism could be used only if it produces ESIs that satisfy - Type 0 (T=0x00) - This type indicates an arbitrary nine-octet ESI
the uniqueness requirement specified above. value, which is managed and configured by the operator.
2. In the case of indirectly connected hosts via a bridged LAN - Type 1 (T=0x01) - When IEEE 802.1AX LACP is used between the PEs
between the CEs and the PEs, the ESI is determined based on the and CEs, this ESI type indicates an auto-generated ESI value
Layer 2 bridge protocol as follows: If MST is used in the bridged determined from LACP by concatenating the following parameters:
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
run MST. However the PE must learn the Root Bridge MAC address
and Bridge Priority of the root of the Internal Spanning Tree
(IST) by listening to the BPDUs. The ESI is constructed as
follows:
{Bridge Priority (16 bits) , Root Bridge MAC Address (48 bits)} + CE LACP six octets System MAC address. The CE LACP System MAC
This mechanism could be used only if it produces ESIs that satisfy address MUST be encoded in the high order six octets of the ESI
the uniqueness requirement specified above. Value field.
3. The ESI may be configured. + CE LACP two octets Port Key. The CE LACP port key MUST be
encoded in the two octets next to the System MAC address.
7. Ethernet Tag + The remaining octet will be set to 0x00.
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
to aggregate links that are attached to different PEs in the
same bundle.
This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above.
- Type 2 (T=0x02) - This type is used in the case of indirectly
connected hosts via a bridged LAN between the CEs and the PEs. The
ESI Value is auto-generated and determined based on the 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 the Ethernet
segment. To achieve this the PE is not required to run MST. However
the PE must learn the Root Bridge MAC address and Bridge Priority of
the root of the Internal Spanning Tree (IST) by listening to the
BPDUs. The ESI Value is constructed as follows:
+ Root Bridge six octets MAC address. The Root Bridge MAC
address MUST be encoded in the high order six octets of the
ESI Value field.
+ Root Bridge two octets Priority. The CE LACP port key MUST be
encoded in the two octets next to the Root Bridge MAC address.
+ The remaining octet will be set to 0x00.
This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above.
- Type 3 (T=0x03) - This type indicates a MAC-based ESI Value that
can be auto-generated or configured by the operator. The ESI Value is
constructed as follows:
+ System MAC address (six octets). The System MAC address MUST
be encoded in the high order six octets of the ESI Value field.
+ Local Discriminator value (three octets). The Local
Discriminator MUST be encoded in the low order three octets
of the ESI Value.
This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above.
- Type 4 (T=0x04) - This type indicates an IP-based ESI Value that
can be auto-generated or configured by the operator. The ESI Value is
constructed as follows:
+ IP address (four octets). This is an IPv4 address owned by
the system and MUST be encoded in the high order four octets
of the ESI Value field.
+ Local Discriminator value (four octets). The Local Discriminator
MUST be encoded in the four octets next to the IP address.
+ The low order octet of the ESI Value will be set to 0x00.
This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above.
- Type 5 (T=0x05) - This type indicates an AS-based ESI Value that
can be auto-generated or configured by the operator. The ESI Value is
constructed as follows:
+ AS number (four octets). This is an AS number owned by the
system and MUST be encoded in the high order four octets of the
ESI Value field. If a two-octet AS number is used, the high order
extra two bytes will be 0x0000.
+ Local Discriminator value (four octets). The Local Discriminator
MUST be encoded in the four octets next to the AS number.
+ The low order octet of the ESI Value will be set to 0x00.
This mechanism could be used only if it produces ESIs that satisfy
the uniqueness requirement specified above.
6. 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 EVPN Instance. An EVPN Instance consists of one or more VLAN, in an EVPN Instance. An EVPN Instance consists of one or more
broadcast domains (one or more VLANs). VLANs are assigned to a given broadcast domains (one or more VLANs). VLANs are assigned to a given
EVPN Instance by the provider of the EVPN service. A given VLAN can EVPN Instance by the provider of the EVPN service. A given VLAN can
itself be represented by multiple VLAN IDs (VIDs). In such cases, the itself be represented by multiple VLAN IDs (VIDs). In such cases, the
PEs participating in that VLAN for a given EVPN instance are PEs participating in that VLAN for a given EVPN instance are
responsible for performing VLAN ID translation to/from locally responsible for performing VLAN ID translation to/from locally
attached CE devices. attached CE devices.
skipping to change at page 9, line 36 skipping to change at page 10, line 40
each EVPN instance to be derived automatically from the corresponding each EVPN instance to be derived automatically from the corresponding
VID, as described in section 9.4.1.1.1 "Auto-Derivation from the VID, as described in section 9.4.1.1.1 "Auto-Derivation from the
Ethernet Tag ID". Ethernet Tag ID".
The following subsections discuss the relationship between broadcast The following subsections discuss the relationship between broadcast
domains (e.g., VLANs), Ethernet Tags (e.g., VIDs), and MAC-VRFs as domains (e.g., VLANs), Ethernet Tags (e.g., VIDs), and MAC-VRFs as
well as the setting of the Ethernet Tag Identifier, in the various well as the setting of the Ethernet Tag Identifier, in the various
EVPN BGP routes (defined in section 8), for the different types of EVPN BGP routes (defined in section 8), for the different types of
service interfaces described in [EVPN-REQ]. service interfaces described in [EVPN-REQ].
7.1 VLAN Based Service Interface The following Ethernet Tag value is reserved:
- Ethernet Tag {0xFFFFFFFF} is known as MAX-ET
6.1 VLAN Based Service Interface
With this service interface, an EVPN instance consists of only a With this service interface, an EVPN instance consists of only a
single broadcast domain (e.g., a single VLAN). Therefore, there is a single broadcast domain (e.g., a single VLAN). Therefore, there is a
one to one mapping between a VID on this interface and a MAC-VRF. one to one mapping between a VID on this interface and a MAC-VRF.
Since a MAC-VRF corresponds to a single VLAN, it consists of a single Since a MAC-VRF corresponds to a single VLAN, it consists of a single
bridge domain corresponding to that VLAN. If the VLAN is represented bridge domain corresponding to that VLAN. If the VLAN is represented
by different VIDs on different PEs, then each PE needs to perform VID by different VIDs on different PEs, then each PE needs to perform VID
translation for frames destined to its attached CEs. In such translation for frames destined to its attached CEs. In such
scenarios, the Ethernet frames transported over MPLS/IP network scenarios, the Ethernet frames transported over MPLS/IP network
SHOULD remain tagged with the originating VID and a VID translation SHOULD remain tagged with the originating VID and a VID translation
MUST be supported in the data path and MUST be performed on the MUST be supported in the data path and MUST be performed on the
disposition PE. The Ethernet Tag Identifier in all EVPN routes MUST disposition PE. The Ethernet Tag Identifier in all EVPN routes MUST
be set to 0. be set to 0.
7.2 VLAN Bundle Service Interface 6.2 VLAN Bundle Service Interface
With this service interface, an EVPN instance corresponds to several With this service interface, an EVPN instance corresponds to several
broadcast domains (e.g., several VLANs); however, only a single broadcast domains (e.g., several VLANs); however, only a single
bridge domain is maintained per MAC-VRF which means multiple VLANs bridge domain is maintained per MAC-VRF which means multiple VLANs
share the same bridge domain. This implies MAC addresses MUST be share the same bridge domain. This implies MAC addresses MUST be
unique across different VLANs for this service to work. In other unique across different VLANs for this service to work. In other
words, there is a many-to-one mapping between VLANs and a MAC-VRF, words, there is a many-to-one mapping between VLANs and a MAC-VRF,
and the MAC-VRF consists of a single bridge domain. Furthermore, a and the MAC-VRF consists of a single bridge domain. Furthermore, a
single VLAN must be represented by a single VID - e.g., no VID single VLAN must be represented by a single VID - e.g., no VID
translation is allowed for this service interface type. The MPLS translation is allowed for this service interface type. The MPLS
encapsulated frames MUST remain tagged with the originating VID. Tag encapsulated frames MUST remain tagged with the originating VID. Tag
translation is NOT permitted. The Ethernet Tag Identifier in all EVPN translation is NOT permitted. The Ethernet Tag Identifier in all EVPN
routes MUST be set to 0. routes MUST be set to 0.
7.2.1 Port Based Service Interface 6.2.1 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 6.3 VLAN Aware Bundle Service Interface
With this service interface, an EVPN instance consists of several With this service interface, an EVPN instance consists of several
broadcast domains (e.g., several VLANs) with each VLAN having its own broadcast domains (e.g., several VLANs) with each VLAN having its own
bridge domain - e.g., multiple bridge domains (one per VLAN) is bridge domain - e.g., multiple bridge domains (one per VLAN) is
maintained by a single MAC-VRF corresponding to the EVPN instance. In maintained by a single MAC-VRF corresponding to the EVPN instance. In
the case where a single VLAN is represented by different VIDs on the case where a single VLAN is represented by different VIDs on
different CEs and thus tag (VID) translation is required, a different CEs and thus tag (VID) translation is required, a
normalized Ethernet Tag (VID) MUST be carried in the MPLS normalized Ethernet Tag (VID) MUST be carried in the MPLS
encapsulated frames and a tag translation function MUST be supported encapsulated frames and a tag translation function MUST be supported
in the data path. This translation MUST be performed in data path on in the data path. This translation MUST be performed in data path on
both the imposition as well as the disposition PEs (translating to both the imposition as well as the disposition PEs (translating to
normalized tag on imposition PE and translating to local tag on normalized tag on imposition PE and translating to local tag on
disposition PE). The Ethernet Tag Identifier in all EVPN routes MUST disposition PE). The Ethernet Tag Identifier in all EVPN routes MUST
be set to the normalized Ethernet Tag assigned by the EVPN provider. be set to the normalized Ethernet Tag assigned by the EVPN provider.
7.3.1 Port Based VLAN Aware Service Interface 6.3.1 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 EVPN NLRI 7. BGP EVPN NLRI
This document defines a new BGP NLRI, called the EVPN NLRI. This document defines a new BGP NLRI, called the EVPN NLRI.
Following is the format of the EVPN NLRI: Following is the format of the EVPN NLRI:
+-----------------------------------+ +-----------------------------------+
| Route Type (1 octet) | | Route Type (1 octet) |
+-----------------------------------+ +-----------------------------------+
| Length (1 octet) | | Length (1 octet) |
+-----------------------------------+ +-----------------------------------+
skipping to change at page 11, line 40 skipping to change at page 12, line 49
Extensions [RFC4760] with an AFI of 25 (L2VPN) and a SAFI of 70 Extensions [RFC4760] with an AFI of 25 (L2VPN) and a SAFI of 70
(EVPN). 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 EVPN NLRI (encoded as specified above). contains the EVPN NLRI (encoded as specified above).
In order for two BGP speakers to exchange labeled EVPN 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 (EVPN). AFI of 25 (L2VPN) and a SAFI of 70 (EVPN).
8.1. Ethernet Auto-Discovery Route 7.1. Ethernet Auto-Discovery Route
A Ethernet A-D route type specific EVPN 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 the purpose of BGP route key processing, only the Ethernet
Segment ID and the Ethernet Tag ID are considered to be part of the
prefix in the NLRI. The MPLS Label field is to be treated as a
route attribute as opposed to being part of the route.
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 7.2. MAC/IP Advertisement Route
A MAC advertisement route type specific EVPN 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) |
+---------------------------------------+ +---------------------------------------+
| MAC Address (6 octets) | | MAC Address (6 octets) |
+---------------------------------------+ +---------------------------------------+
| IP Address Length (1 octet) | | IP Address Length (1 octet) |
+---------------------------------------+ +---------------------------------------+
| IP Address (4 or 16 octets) | | IP Address (0 or 4 or 16 octets) |
+---------------------------------------+ +---------------------------------------+
| MPLS Label (3 octets) | | MPLS Label1 (3 octets) |
+---------------------------------------+
| MPLS Label2 (0 or 3 octets) |
+---------------------------------------+ +---------------------------------------+
For the purpose of BGP route key processing, only the Ethernet Tag For the purpose of BGP route key processing, only the Ethernet Tag
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 7.3. Inclusive Multicast Ethernet Tag Route
An Inclusive Multicast Ethernet Tag route type specific EVPN 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 7.4 Ethernet Segment Route
The Ethernet Segment Route is encoded in the EVPN 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) | | 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 9.5 For procedures and usage of this route please see section 9.5
"Designated Forwarder Election". "Designated Forwarder Election". The IP address length is in bits.
8.5 ESI Label Extended Community 7.5 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
section 9.3 "Split Horizon". section 9.3 "Split Horizon".
Each ESI Label Extended Community is encoded as a 8-octet value as Each ESI Label 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=0x01 | Flags (One Octet) |Reserved=0 | | Type=0x06 | Sub-Type=0x01 | Flags (One Octet) |Reserved=0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved = 0| ESI Label | | Reserved = 0| ESI Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The low order bit of the flags octet is defined as the "Active- The low order bit of the flags octet is defined as the "Single-
Standby" bit and may be set to 1. A value of 0 means that the multi- Active" bit. A value of 0 means that the multi-homed site is
homed site is operating in All-Active mode; whereas, a value of 1 operating in All-Active redundancy mode and a value of 1 means that
means that the multi-homed site is operating in Single-Active mode. the multi-homed site is operating in Single-Active redundancy mode.
The second low order bit of the flags octet is defined as the "Root- The second low order bit of the flags octet is defined as the "Root-
Leaf". A value of 0 means that this label is associated with a Root Leaf". A value of 0 means that this label is associated with a Root
site; whereas, a value of 1 means that this label is associate with a site; whereas, a value of 1 means that this label is associate with a
Leaf site. The other bits must be set to 0. Leaf site. The other bits must be set to 0.
8.6 ES-Import Route Target 7.6 ES-Import Route Target
This is a new transitive Route Target extended community carried with This is a new transitive Route Target extended community carried with
the Ethernet Segment route. When used, it enables all the PEs the Ethernet Segment route. When used, it enables all the PEs
connected to the same multi-homed site to import the Ethernet Segment connected to the same multi-homed site to import the Ethernet Segment
routes. The value is derived automatically from the ESI by encoding routes. The value is derived automatically from the ESI by encoding
the 6-byte MAC address portion of the ESI in the ES-Import Route the high order 6-byte portion of the 9-byte ESI Value in the ES-
Target. The format of this extended community is as follows: Import Route Target. The format of this extended community is as
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=0x02 | ES-Import | | Type=0x06 | Sub-Type=0x02 | ES-Import |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ES-Import Cont'd | | ES-Import Cont'd |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This document expands the definition of the Route Target extended This document expands the definition of the Route Target extended
community to allow the value of high order octet (Type field) to be community to allow the value of high order octet (Type field) to be
skipping to change at page 14, line 51 skipping to change at page 16, line 14
low order octet (Sub-Type field) of 0x02 indicates that this extended low order octet (Sub-Type field) of 0x02 indicates that this extended
community is of type "Route Target". The new value for Type field of community is of type "Route Target". The new value for Type field of
0x06 indicates that the structure of this RT is a six bytes value 0x06 indicates that the structure of this RT is a six bytes value
(e.g., a MAC address). A BGP speaker that implements RT-Constrain (e.g., a MAC address). A BGP speaker that implements RT-Constrain
(RFC4684) MUST apply the RT-Constrain procedures to the ES-import RT (RFC4684) MUST apply the RT-Constrain procedures to the ES-import RT
as-well. as-well.
For procedures and usage of this attribute, please see section 9.1 For procedures and usage of this attribute, please see section 9.1
"Redundancy Group Discovery". "Redundancy Group Discovery".
8.7 MAC Mobility Extended Community 7.7 MAC Mobility 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 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 |Flags(1 octet)| 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 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 "Sticky/static" flag and may be set to 1. A value of 1 means that the
MAC address is static and cannot move. MAC address is static and cannot move.
8.8 Default Gateway Extended Community 7.8 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 8. 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 EVPN. 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 8.1 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 8.1.1 Constructing the Ethernet Segment Route
The Route-Distinguisher (RD) MUST be a Type 1 RD [RFC4364]. The value The Route-Distinguisher (RD) MUST be a Type 1 RD [RFC4364]. The value
field comprises an IP address of the MES (typically, the loopback field comprises an IP address of the MES (typically, the loopback
address) followed by 0's. address) followed by 0's.
The Ethernet Segment Identifier MUST be set to the ten octet ESI The Ethernet Segment Identifier MUST be set to the ten octet ESI
identifier described in section 6. identifier described in section 6.
The BGP advertisement that advertises the Ethernet Segment route MUST The BGP advertisement that advertises the Ethernet Segment route MUST
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.
9.2 Fast Convergence 8.2 Fast Convergence
In EVPN, MAC address reachability is learnt via the BGP control-plane In EVPN, MAC address reachability is learnt via the BGP control-plane
over the MPLS network. As such, in the absence of any fast protection over the MPLS network. As such, in the absence of any fast protection
mechanism, the network convergence time is a function of the number mechanism, the network convergence time is a function of the number
of MAC Advertisement routes that must be withdrawn by the PE of MAC Advertisement routes that must be withdrawn by the PE
encountering a failure. For highly scaled environments, this scheme encountering a failure. For highly scaled environments, this scheme
yields slow convergence. yields slow convergence.
To alleviate this, EVPN 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 a set
Ethernet A-D Route per Ethernet segment for each locally attached of Ethernet A-D per Ethernet segment (per ES) routes for each locally
segment (refer to section 9.2.1 below for details on how this route attached Ethernet segment (refer to section 9.2.1 below for details
is constructed). Upon a failure in connectivity to the attached on how this route is constructed). Upon a failure in connectivity to
segment, the PE withdraws the corresponding Ethernet A-D route. This the attached segment, the PE withdraws the corresponding Ethernet A-D
triggers all PEs that receive the withdrawal to update their next-hop route. This triggers all PEs that receive the withdrawal to update
adjacencies for all MAC addresses associated with the Ethernet their next-hop adjacencies for all MAC addresses associated with the
segment in question. If no other PE had advertised an Ethernet A-D Ethernet segment in question. If no other PE had advertised an
route for the same segment, then the PE that received the withdrawal Ethernet A-D route for the same segment, then the PE that received
simply invalidates the MAC entries for that segment. Otherwise, the the withdrawal simply invalidates the MAC entries for that segment.
PE updates the next-hop adjacencies to point to the backup PE(s).
9.2.1 Constructing the Ethernet A-D Route per Ethernet Segment Otherwise, the PE updates the next-hop adjacencies to point to the
backup PE(s).
This section describes procedures to construct the Ethernet A-D route 8.2.1 Constructing the Ethernet A-D per Ethernet Segment (ES) Route
when a single such route is advertised by an PE for a given Ethernet
Segment. This flavor of the Ethernet A-D route is used for fast
convergence (as discussed above) as well as for advertising the ESI
label used for split-horizon filtering (as discussed in section 9.3).
Support of this route flavor is MANDATORY.
Route-Distinguisher (RD) MUST be a Type 1 RD [RFC4364]. The value This section describes the procedures used to construct the Ethernet
A-D per ES route, which is used for fast convergence (as discussed
above) and for advertising the ESI label used for split-horizon
filtering (as discussed in section 9.3). Support of this route is
MANDATORY.
The Route-Distinguisher (RD) MUST be a Type 1 RD [RFC4364]. The value
field comprises an IP address of the PE (typically, the loopback field comprises an IP address of the PE (typically, the loopback
address) followed by 0. address) followed by a number unique to the PE.
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". This document does not described in section "Ethernet Segment". This document does not
specify the use of the Ethernet A-D route when the Segment Identifier specify the use of the Ethernet A-D route when the Segment Identifier
is set to 0. is set to 0.
The Ethernet Tag ID MUST be set to 0. The Ethernet Tag ID MUST be set to MAX-ET.
The MPLS label in the NLRI MUST be set to 0. The MPLS label in the NLRI MUST be set to 0.
The "ESI Label Extended Community" MUST be included in the route. If The "ESI Label Extended Community" MUST be included in the route. If
all-Active multi-homing is desired, then the "Active-Standby" bit in All-Active redundancy mode is desired, then the "Single-Active" bit
the flags of the ESI Label Extended Community MUST be set to 0 and in the flags of the ESI Label Extended Community MUST be set to 0 and
the MPLS label in that extended community MUST be set to a valid MPLS the MPLS label in that extended community MUST be set to a valid MPLS
label value. The MPLS label in this Extended Community is referred to label value. The MPLS label in this Extended Community is referred to
as an "ESI label". This label MUST be a downstream assigned MPLS as the ESI label and MUST have the same value in each Ethernet A-D
label if the advertising PE is using ingress replication for per ES route advertised for the ES. This label MUST be a downstream
receiving multicast, broadcast or unknown unicast traffic from other assigned MPLS label if the advertising PE is using ingress
PEs. If the advertising PE is using P2MP MPLS LSPs for sending replication for receiving multicast, broadcast or unknown unicast
multicast, broadcast or unknown unicast traffic, then this label MUST traffic from other PEs. If the advertising PE is using P2MP MPLS LSPs
be an upstream assigned MPLS label. The usage of this label is for sending multicast, broadcast or unknown unicast traffic, then
described in section 9.3. this label MUST be an upstream assigned MPLS label. The usage of this
label is described in section 9.3.
If the Ethernet Segment is connected to more than one PE and Single- If Single-Active redundancy mode is desired, then the "Single-Active"
Active multi-homing is desired, then the "Active-Standby" bit in the bit in the flags of the ESI Label Extended Community MUST be set to 1
flags of the ESI Label Extended Community MUST be set to 1 and ESI and the ESI label MUST be set to zero.
label MUST be set to zero.
9.2.1.1. Ethernet A-D Route Targets 8.2.1.1. Ethernet A-D Route Targets
The Ethernet A-D route MUST carry one or more Route Target (RT) Each Ethernet A-D per ES route MUST carry one or more Route Target
attributes. These RTs MUST be the set of RTs associated with all the (RT) attributes. The set of Ethernet A-D routes per ES MUST carry the
EVPN instances to which the Ethernet Segment, corresponding to the entire set of RTs for all the EVPN instances to which the Ethernet
Ethernet A-D route, belongs. Segment belongs.
9.3 Split Horizon 8.3 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 redundancy mode. If the CE sends
broadcast, unknown unicast, or multicast (BUM) packet to one of the a 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 that EVPN instance that packet to all or subset of the other PEs in that EVPN instance
including the DF PE for that Ethernet segment. In this case the DF PE including the DF PE for that Ethernet segment. In this case the DF PE
that the CE is multi-homed to MUST drop the packet and not forward that the CE is multi-homed to MUST drop the packet and not forward
back to the CE. This filtering is referred to as "split horizon" back to the CE. This filtering is referred to as "split horizon"
filtering in 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 EVPN 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 redundancy mode using a set of Ethernet A-D per ES
Ethernet Segment" as per the procedures in section 9.2.1 above. This routes per section 9.2.1 above. This route is imported by the PEs
route is imported by the PEs connected to the Ethernet Segment and connected to the Ethernet Segment and also by the PEs that have at
also by the PEs that have at least one EVPN instance in common with least one EVPN instance in common with the Ethernet Segment in the
the Ethernet Segment in the route. As described in section 9.1.1, the route. As described in section 9.1.1, the route MUST carry an ESI
route MUST carry an ESI Label Extended Community with a valid ESI Label Extended Community with a valid ESI label. The disposition DF
label. The disposition DF PE rely on the value of the ESI label to PE rely on the value of the ESI label to determine whether or not a
determine whether or not a BUM frame is allowed to egress a specific BUM frame is allowed to egress a specific Ethernet segment. It should
Ethernet segment. It should be noted that if the BUM frame is be noted that if the BUM frame is originated from the DF PE operating
originated from the DF PE operating in All-Active multi-homing mode, in All-Active multi-homing mode, then the DF PE MAY not encapsulate
then the DF PE MAY not encapsulate the frame with the ESI label. the frame with the ESI label. Furthermore, if the multi-homed PEs
Furthermore, if the multi-homed PEs operate in active/standby mode, operate in Single-Active redundancy mode, then the packet MUST NOT be
then the packet MUST NOT be encapsulated with the ESI label and the encapsulated with the ESI label and the label value MUST be set to
label value MUST be set to zero in ESI Label Extended Community per zero in ESI Label Extended Community per section 9.2.1 above.
section 9.2.1 above.
9.3.1 ESI Label Assignment 8.3.1 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 EVPN network. to deliver multi-destination packets in the EVPN network.
9.3.1.1 Ingress Replication 8.3.1.1 Ingress Replication
All PEs operating in an All-Active multi-homing mode that rely on The non-DF PEs attached to a given ES that is operating in All-Active
ingress replication for the reception of BUM traffic, distribute to redundancy mode and that use ingress replication to receive BUM
other PEs, that belong to the Ethernet segment, a downstream assigned traffic advertise a downstream assigned ESI label in the set of
"ESI label" in the Ethernet A-D route per ESI. This label MUST be Ethernet A-D per ES routes for that ES. This label MUST be programmed
programmed in the platform label space by the advertising PE. Further in the platform label space by the advertising PE. Further the
the forwarding entry for this label must result in NOT forwarding forwarding entry for this label must result in NOT forwarding packets
packets received with this label onto the Ethernet segment that the received with this label onto the Ethernet segment that the label was
label was distributed for. 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 corresponding to an Inclusive Multicast Ethernet Tag route for VLAN1 corresponding to an
EVPN instance. So, when PE1 sends a BUM packet, that it receives from EVPN instance. So, when PE1 sends a BUM packet, that it receives from
CE1, it MUST first push onto the MPLS label stack the ESI label that CE1, it MUST first push onto the MPLS label stack the ESI label that
PE2 has distributed for ES1. It MUST then push on the MPLS label PE2 has distributed for ES1. It MUST then push on the MPLS label
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the packet to from the top MPLS label, after any P2P or MP2P LSP the packet to from the top MPLS label, after any P2P or MP2P LSP
labels have been removed. If the next label is the ESI label assigned labels have been removed. If the next label is the ESI label assigned
by PE2 for ES1, then PE2 MUST NOT forward the packet onto ES1. If the by PE2 for ES1, then PE2 MUST NOT forward the packet onto ES1. If the
next label is an ESI label which has not been assigned by PE2, then next label is an ESI label which has not been assigned by PE2, then
PE2 MUST drop the packet. It should be noted that in this scenario, PE2 MUST drop the packet. It should be noted that in this scenario,
if PE2 receives a BUM traffic for VLAN1 from CE1, then it doesn't if PE2 receives a BUM traffic for VLAN1 from CE1, then it doesn't
need to encapsulate the packet with an ESI label when sending it to need to encapsulate the packet with an ESI label when sending it to
the PE1 since PE1 can use its DF logic to filter the BUM packets and the PE1 since PE1 can use its DF logic to filter the BUM packets and
thus doesn't need to use split-horizon filtering for ES1. thus doesn't need to use split-horizon filtering for ES1.
9.3.1.2. P2MP MPLS LSPs 8.3.1.2. P2MP MPLS LSPs
The non-DF PEs operating in an All-Active multi-homing mode that is The non-DF PEs attached to a given ES that is operating in All-Active
using P2MP LSPs for sending BUM traffic, distribute to other PEs, redundancy mode and that use P2MP LSPs to send BUM traffic advertise
that belong to the Ethernet segment or have an EVPN instance in an upstream assigned ESI label in the set of Ethernet A-D per ES
common with the Ethernet Segment, an upstream assigned "ESI label" in routes for that ES. 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 belongs to one of in All-Active multi-homing mode. Also consider PE3 belongs to one of
the EVPN instances of ES1. Further, assume that PE1 which is the the EVPN instances of ES1. Further, assume that PE1 which is the
non-DF, using P2MP MPLS LSPs to send BUM packets. When PE1 sends a non-DF, using P2MP MPLS LSPs to send BUM packets. When PE1 sends a
BUM packet, that it receives from CE1, it MUST first push onto the BUM packet, that it receives from CE1, it MUST first push onto the
MPLS label stack the ESI label that it has assigned for the ESI that MPLS label stack the ESI label that it has assigned for the ESI that
the packet was received on. The resulting packet is further the packet was received on. The resulting packet is further
encapsulated in the P2MP MPLS label stack necessary to transmit the encapsulated in the P2MP MPLS label stack necessary to transmit the
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ES1, then PE2 MUST NOT forward the packet onto ES1. When PE3 receives ES1, then PE2 MUST NOT forward the packet onto ES1. When PE3 receives
this packet, it de-capsulates the top MPLS label and forwards the this packet, it de-capsulates the top MPLS label and forwards the
packet using the context label space determined by the top label. If packet using the context label space determined by the top label. If
the next label is the ESI label assigned by PE1 to ES1 and PE3 is not the next label is the ESI label assigned by PE1 to ES1 and PE3 is not
connected to ES1, then PE3 MUST pop the label and flood the packet connected to ES1, then PE3 MUST pop the label and flood the packet
over all local ESIs in that EVPN instance. It should be noted that over all local ESIs in that EVPN instance. It should be noted that
when PE2 sends a BUM frame over a P2MP LSP, it does not need to when PE2 sends a BUM frame over a P2MP LSP, it does not need to
encapsulate the frame with an ESI label because it is the DF for that encapsulate the frame with an ESI label because it is the DF for that
VLAN. VLAN.
9.4 Aliasing and Backup-Path 8.4 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, EVPN introduces the concept of 'Aliasing'. To address this issue, EVPN introduces the concept of 'Aliasing'
Aliasing refers to the ability of a PE to signal that it has which is the ability of a PE to signal that it has reachability to an
reachability to a given locally attached Ethernet segment, even when EVPN instance on a given ES even when it has learnt no MAC addresses
it has learnt no MAC addresses from that segment. The Ethernet A-D from that EVI/ES. The Ethernet A-D per EVI route is used for this
route per EVI is used to that end. Remote PEs which receive MAC purpose. A remote PE that receives a MAC advertisement route with
advertisement routes with non-reserved ESI SHOULD consider the non-reserved ESI SHOULD consider the advertised MAC address to be
advertised MAC address as reachable via all PEs which have advertised reachable via all PEs that have advertised reachability to that MAC
reachability to the relevant Segment using: (1) Ethernet A-D routes address' EVI/ES via the combination of an Ethernet A-D per EVI route
per EVI with the same ESI (and Ethernet Tag if applicable) AND for that EVI/ES (and Ethernet Tag if applicable) AND Ethernet A-D per
(2)Ethernet A-D routes per ESI with the same ESI and with the ES routes for that ES with the 'Single-Active' bit in the flags of
Active/Standby bit set to 0 in the ESI Label Extended Community. the ESI Label Extended Community set to 0.
This flavor of Ethernet A-D route per EVI, associated with aliasing, Note that the Ethernet A-D per EVI route may be received by a remote
can arrive at target PEs asynchronously relative to the flavor of PE before it receives the set of Ethernet A-D per ES routes.
Ethernet A-D route associated with split-horizon and mass-withdraw Therefore, in order to handle corner cases and race conditions, the
(i.e. per ESI). Therefore, if the Ethernet A-D route per EVI arrives Ethernet A-D per EVI route MUST NOT be used for traffic forwarding by
ahead of the Ethernet A-D route per ESI, then the former must NOT be a remote PE until it also receives the associated set of Ethernet A-D
used for traffic forwarding till the latter arrives. This will take per ES routes.
care of corner cases and race conditions where the Ethernet A-D route
associated with mass-withdraw is withdrawn but a PE still receives
the route associated with aliasing.
Backup-Path is a closely related function, albeit it applies to the Backup-path is a closely related function, but it is used in Single-
case where the redundancy mode is Active/Standby. In this case, the Active redundancy mode. In this case a PE also advertises that it
PE advertises that it has reachability to a given locally attached has reachability to a give EVI/ES using same combination of Ethernet
Ethernet Segment using the Ethernet A-D route as well. Remote PEs A-D per EVI route and Ethernet A-D per ES route as above, but with
which receive the MAC advertisement routes, with non-reserved ESI, the 'Single-Active' bit in the flags of the ESI Label Extended
MUST consider the MAC address as reachable via the advertising PE. Community set to 1. A remote PE that receives a MAC advertisement
Furthermore, the remote PEs SHOULD install a Backup-Path, for said route with non-reserved ESI SHOULD consider the advertised MAC
MAC, to the PE which had advertised reachability to the relevant address to be reachable via any PE that has advertised this
Segment using (1) an Ethernet A-D routes per EVI with the same ESI combination of Ethernet A-D routes and it SHOULD install a backup-
(and Ethernet Tag if applicable) AND (2) Ethernet A-D routes per ESI path for that MAC address.
with the same ESI and with the Active/Standby bit set to 1 in the ESI
Label Extended Community.
9.4.1 Constructing the Ethernet A-D Route per EVI 8.4.1 Constructing the Ethernet A-D per EVPN Instance (EVI) Route
This section describes procedures to construct the Ethernet A-D route This section describes the procedures used to construct the Ethernet
when one or more such routes are advertised by an PE for a given EVI. A-D per EVPN Instance (EVI) route, which is used for aliasing (as
This flavor of the Ethernet A-D route is used for aliasing, and discussed above). Support of this route 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 EVPN 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.
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Tag ID is set to 0). This is applicable when the PE uses Tag ID is set to 0). This is applicable when the PE uses
MAC-based disposition, or when the PE uses MPLS-based MAC-based disposition, or when the PE uses MPLS-based
disposition when no VLAN translation is required. disposition when no VLAN translation is required.
The usage of the MPLS label is described in the section on "Load The usage of the MPLS label is described in the section on "Load
Balancing of Unicast Packets". Balancing of Unicast Packets".
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.
9.4.1.1 Ethernet A-D Route Targets 8.4.1.1 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. RTs may be configured (as in IP VPNs), or may be derived attributes. RTs may be configured (as in IP VPNs), or may be derived
automatically. automatically.
If an PE uses Route Target Constrain [RT-CONSTRAIN], the PE SHOULD If an PE uses Route Target Constrain [RT-CONSTRAIN], the PE SHOULD
advertise all such RTs using Route Target Constrains. The use of RT advertise all such RTs using Route Target Constrains. The use of RT
Constrains allows each Ethernet A-D route to reach only those PEs Constrains allows each Ethernet A-D route to reach only those PEs
that are configured to import at least one RT from the set of RTs that are configured to import at least one RT from the set of RTs
carried in the Ethernet A-D route. carried in the Ethernet A-D route.
9.4.1.1.1 Auto-Derivation from the Ethernet Tag ID 8.4.1.1.1 Auto-Derivation from the Ethernet Tag ID
The following is the procedure for deriving the RT attribute The following is the procedure for deriving the RT attribute
automatically from the Ethernet Tag ID associated with the automatically from the Ethernet Tag ID associated with the
advertisement: advertisement:
+ 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 EVPN" 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 EVPN. the Ethernet Tag, e.g., VLAN ID for that EVPN.
9.5 Designated Forwarder Election 8.5 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 EVPN instance on a given Ethernet segment. to more than one PE in an EVPN instance on a given Ethernet segment.
One or more Ethernet Tags may be configured on the Ethernet segment. One or more Ethernet Tags may be configured on the Ethernet segment.
In this scenario only one of the PEs, referred to as the Designated In this scenario only one of the PEs, referred to as the Designated
Forwarder (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.
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unicast traffic, is the default behavior in this specification. unicast traffic, is the default behavior in this specification.
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 EVPN If a bridged network is multi-homed to more than one PE in an EVPN
network via switches, then the support of All-Active points of network via switches, then the support of All-Active redundancy mode
attachments, as described in this specification, requires the bridge requires the bridge network to be connected to two or more PEs using
network to be connected to two or more PEs using a LAG. In this case a LAG.
the reasons for doing DF election are the same as those described
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 EVPN instance. In this case, the
Ethernet A-D route per Ethernet segment MUST be advertised with the set of Ethernet A-D per ES routes advertised by each PE MUST have the
"Active-Standby" flag set to one. Procedures for supporting All- 'Single-Active' bit in the flags of the ESI Label Extended Community
Active points of attachments, when a bridge network connects to the set to 1.
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,
EVI> is referred to as "service carving". With service carving, it is EVI> is referred to as "service carving". With service carving, it is
possible to elect multiple DFs per Ethernet Segment (one per EVI) in possible to elect multiple DFs per Ethernet Segment (one per EVI) in
order to perform load-balancing of multi-destination traffic destined order to perform load-balancing of multi-destination traffic destined
to a given Segment. The load-balancing procedures carve up the EVI to a given Segment. The load-balancing procedures carve up the EVI
space among the PE nodes evenly, in such a way that every PE is the space among the PE nodes evenly, in such a way that every PE is the
DF for a disjoint set of EVIs. The procedure for service carving is DF for a disjoint set of EVIs. The procedure for service carving is
as follows: as follows:
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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 8.6. Interoperability with Single-homing PEs
Let's refer to PEs that only support single-homed CE devices as 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 single-homing PEs. For single-homing PEs, all the above multi-homing
procedures can be omitted; however, to allow for single-homing PEs to procedures can be omitted; however, to allow for single-homing PEs to
fully inter-operate with multi-homing PEs, some of the multi-homing fully inter-operate with multi-homing PEs, some of the multi-homing
procedures described above SHOULD be supported even by single-homing procedures described above SHOULD be supported even by single-homing
PEs: PEs:
- procedures related to processing Ethernet A-D route for the purpose - procedures related to processing Ethernet A-D route for the purpose
of Fast Convergence (9.2 Fast Convergence), to let single-homing PEs of Fast Convergence (9.2 Fast Convergence), to let single-homing PEs
benefit from fast convergence benefit from fast convergence
- procedures related to processing Ethernet A-D route for the purpose - procedures related to processing Ethernet A-D route for the purpose
of Aliasing (9.4 Aliasing and Backup-path), to let single-homing PEs of Aliasing (9.4 Aliasing and Backup-path), to let single-homing PEs
benefit from load balancing benefit from load balancing
- procedures related to processing Ethernet A-D route for the purpose - procedures related to processing Ethernet A-D route for the purpose
of Backup-path (9.4 Aliasing and Backup-path), to let single-homing of Backup-path (9.4 Aliasing and Backup-path), to let single-homing
PEs to benefit from the corresponding convergence improvement PEs to benefit from the corresponding convergence improvement
10. Determining Reachability to Unicast MAC Addresses 9. 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 9.1. 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 EVPN instance MUST support local data plane The PEs in a particular EVPN instance MUST support local data plane
learning using standard IEEE Ethernet learning procedures. An PE must learning using standard IEEE Ethernet learning procedures. An PE must
be capable of learning MAC addresses in the data plane when it be capable of learning MAC addresses in the data plane when it
receives packets such as the following from the CE network: receives packets such as the following from the CE network:
- DHCP requests - DHCP requests
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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.
There are applications where a MAC address that is reachable via a There are applications where a MAC address that is reachable via a
given PE on a locally attached Segment (e.g. with ESI X) may move given PE on a locally attached Segment (e.g. with ESI X) may move
such that it becomes reachable via another PE on another Segment such that it becomes reachable via another PE on another Segment
(e.g. with ESI Y). This is referred to as a "MAC Mobility". (e.g. with ESI Y). This is referred to as a "MAC Mobility".
Procedures to support this are described in section "MAC Mobility". Procedures to support this are described in section "MAC Mobility".
10.2. Remote learning 9.2. 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 that EVPN instance, using MP-BGP and plane, to all the other PEs in that EVPN instance, using MP-BGP and
specifically the MAC Advertisement route. specifically the MAC Advertisement route.
10.2.1. Constructing the BGP EVPN MAC Address Advertisement 9.2.1. Constructing the BGP EVPN MAC/IP Address Advertisement
BGP is extended to advertise these MAC addresses using the MAC BGP is extended to advertise these MAC addresses using the MAC/IP
Advertisement route type in the EVPN 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
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prefix. This provides the ability to advertise IP address prefixes prefix. This provides the ability to advertise IP address prefixes
when the deployment environment supports that. The encoding of an IP when the deployment environment supports that. The encoding of an IP
address MUST be either 4 octets for IPv4 or 16 octets for IPv6. When address MUST be either 4 octets for IPv4 or 16 octets for IPv6. When
the IP address is advertised as a prefix, then the trailing bits of the IP address is advertised as a prefix, then the trailing bits of
the prefix MUST be set to 0 to ensure that the entire prefix is the prefix MUST be set to 0 to ensure that the entire prefix is
encoded as either 4 or 16 octets. The length field of EVPN NLRI 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 (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 determine whether an IP address/prefix is encoded in this route and
if so, whether the encoded IP address/prefix is IPV4 or IPv6. 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 The MPLS label1 field is encoded as 3 octets, where the high-order 20
octets, where the high-order 20 bits contain the label value. The bits contain the label value. The MPLS label1 MUST be downstream
MPLS label MUST be the downstream assigned that is used by the PE to assigned and it is associated with the MAC address being advertised
forward MPLS-encapsulated Ethernet frames, where the destination MAC by the advertising PE. The advertising PE uses this label when it
address in the Ethernet frame is the MAC address advertised in the receives an MPLS-encapsulated packet to perform forwarding based on
above NLRI. The forwarding procedures are specified in section the destination MAC address. The forwarding procedures are specified
"Forwarding Unicast Packets" and "Load Balancing of Unicast Packets". in section "Forwarding Unicast Packets" and "Load Balancing of
Unicast Packets".
An PE may advertise the same single EVPN 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
EVPN label per <ESI, Ethernet Tag> combination. This label assignment EVPN label per <ESI, Ethernet Tag> combination. This label assignment
methodology is referred to as a per <ESI, Ethernet Tag> label methodology is referred to as a per <ESI, Ethernet Tag> label
assignment. As a third option, an PE may advertise a unique EVPN assignment. As a third option, an PE may advertise a unique EVPN
label per MAC address. All of these methodologies have their label per MAC address. All of these methodologies have their
tradeoffs. The choice of a particular label assignment methodology is tradeoffs. The choice of a particular label assignment methodology is
purely local to the PE that originates the route. purely local to the PE that originates the route.
Per EVI label assignment requires the least number of EVPN 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 MPLS label2 field is an optional field and if it is present, then
it is encoded as 3 octets, where the high-order 20 bits contain the
label value. The use of MPLS label2 is for further study.
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 EVPN". 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 9.2.2 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,
then the receiving PE MUST install forwarding state for the then the receiving PE MUST install forwarding state for the
associated MAC Address based on the MAC Advertisement route alone. associated MAC Address based on the MAC Advertisement route alone.
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 a non-reserved ESI, and the receiving Advertisement route is set to a non-reserved ESI, and the receiving
PE is locally attached to the same ESI, then the PE does not alter PE is locally attached to the same ESI, then the PE does not alter
its forwarding state based on the received route. This ensures that its forwarding state based on the received route. This ensures that
local routes are preferred to remote routes. local routes are preferred to remote routes.
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 a non-reserved ESI, then the receiving Advertisement route is set to a non-reserved ESI, then the receiving
PE MUST install forwarding state for a given MAC address only when PE MUST install forwarding state for a given MAC address only when
both the MAC Advertisement route AND the associated Ethernet A-D both the MAC Advertisement route AND the associated set of Ethernet
route per ESI have been received. A-D per ES routes have been received.
To illustrate this with an example, consider two PEs (PE1 and PE2) To illustrate this with an example, consider two PEs (PE1 and PE2)
connected to a multi-homed Ethernet Segment ES1. All-Active connected to a multi-homed Ethernet Segment ES1. All-Active
redundancy mode is assumed. A given MAC address M1 is learnt by PE1 redundancy mode is assumed. A given MAC address M1 is learnt by PE1
but not PE2. On PE3, the following states may arise: but not PE2. On PE3, the following states may arise:
T1- When the MAC Advertisement Route from PE1 and the Ethernet A-D T1- When the MAC Advertisement Route from PE1 and the set of Ethernet
routes per ESI from PE1 and PE2 are received, PE3 can forward traffic A-D per ES routes from PE1 and PE2 are received, PE3 can forward
destined to M1 to both PE1 and PE2. traffic destined to M1 to both PE1 and PE2.
T2- If after T1, PE1 withdraws its Ethernet A-D route per ESI, then T2- If after T1, PE1 withdraws its set of Ethernet A-D per ES routes,
PE3 forwards traffic destined to M1 to PE2 only. then PE3 forwards traffic destined to M1 to PE2 only.
T3- If after T1, PE2 withdraws its Ethernet A-D route per ESI, then T3- If after T1, PE2 withdraws its set of Ethernet A-D per ES routes,
PE3 forwards traffic destined to M1 to PE1 only. then PE3 forwards traffic destined to M1 to PE1 only.
T4- If after T1, PE1 withdraws its MAC Advertisement route, then PE3 T4- If after T1, PE1 withdraws its MAC Advertisement route, then PE3
treats traffic to M1 as unknown unicast. Note, here, that had PE2 treats traffic to M1 as unknown unicast. Note, here, that had PE2
also advertised a MAC route for M1 before PE1 withdraws its MAC also advertised a MAC route for M1 before PE1 withdraws its MAC
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 10. 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 EVPN 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. For ARP and ND purposes, the IP Address length field
IPv4 address or to 128 for an IPv6 address. MUST be set to 32 for an 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 by responding to the ARP request. SHOULD perform ARP proxy by responding to the ARP request.
11.1 Default Gateway 10.1 Default Gateway
When a PE needs to perform inter-subnet forwarding where each subnet When a PE needs to perform inter-subnet forwarding where each subnet
is represented by a different broadcast domain (e.g., different VLAN) is represented by a different broadcast domain (e.g., different VLAN)
the inter-subnet forwarding is performed at layer 3 and the PE that the inter-subnet forwarding is performed at layer 3 and the PE that
performs such function is called the default gateway. In this case performs such function is called the default gateway. In this case
when the PE receives an ARP Request for the IP address of the default when the PE receives an ARP Request for the IP address of the default
gateway, the PE originates an ARP Reply. gateway, the PE originates an ARP Reply.
Each PE that acts as a default gateway for a given EVPN instance MAY Each PE that acts as a default gateway for a given EVPN instance MAY
advertise in the EVPN control plane its default gateway 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]. The IP defined in [Section 8.8 Default Gateway Extended Community]. The ESI
address field (4 octets for IPv4, 16 octets for IPv6) is set to zero field is set to zero when advertising the MAC route with the Default
when advertising the MAC route with the Default Gateway extended Gateway extended community.
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 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 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 EVPN instance, the MPLS label MUST be set to a valid downstream
assigned label. assigned label.
Furthermore, even if all PEs of a given EVPN instance do act as a 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, default gateway for that EVPN instance, but only some, but not all,
of these PEs have sufficient (routing) information to provide inter- of these PEs have sufficient (routing) information to provide inter-
subnet routing for all the inter-subnet traffic originated within the subnet routing for all the inter-subnet traffic originated within the
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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 EVPN route. for the IP address in the received EVPN route.
Each PE that acts as a default gateway for a given EVPN instance 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 11. 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 traffic, received from a CE encapsulated in a given Ethernet Tag
(VLAN) in an EVPN instance, to all the other PEs that span that (VLAN) in an EVPN instance, to all the other PEs that span that
Ethernet Tag (VLAN) in that EVPN instance. In certain scenarios, Ethernet Tag (VLAN) in that EVPN instance. In certain scenarios,
described in section "Processing of Unknown Unicast Packets", a given described in section "Processing of Unknown Unicast Packets", a given
PE may also need to flood unknown unicast traffic to other PEs. PE may also need to flood unknown unicast traffic to other PEs.
The PEs in a particular EVPN instance may use ingress replication, The PEs in a particular EVPN instance may use ingress replication,
P2MP LSPs or MP2MP LSPs to send unknown unicast, broadcast or P2MP LSPs or MP2MP LSPs to send unknown unicast, broadcast or
multicast traffic 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 11.1. 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 EVPN instance on a PE are procedures for setting the RD for a given EVPN instance on a PE are
described in 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
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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
EVPN MAC Address Advertisement" MUST be followed. EVPN MAC Address Advertisement" MUST be followed.
12.2. P-Tunnel Identification 11.2. 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 EVPN Depending on the technology used for the P-tunnel for the EVPN
instance on the PE, the PMSI Tunnel attribute of the Inclusive instance on the PE, the PMSI Tunnel attribute of the Inclusive
Multicast Ethernet Tag route is constructed as follows. Multicast Ethernet Tag route is constructed as follows.
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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 EVPN 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 12. 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. When flooding, known by the PE, the PE may have to flood the packet. When flooding,
one must take into account "split horizon forwarding" as follows: The one must take into account "split horizon forwarding" as follows: The
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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 EVPN instance may use ingress replication The PEs in a particular EVPN instance may use ingress replication
using RSVP-TE P2P LSPs or LDP MP2P LSPs for sending unknown unicast using RSVP-TE P2P LSPs or LDP MP2P LSPs for sending unknown unicast
traffic to other PEs. Or they may use RSVP-TE P2MP or LDP P2MP for traffic to other PEs. Or they may use RSVP-TE P2MP or LDP P2MP for
sending such traffic to other PEs. sending such traffic to other PEs.
13.1. Ingress Replication 12.1. 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 EVPN instance, the Inclusive Multicast Ethernet Tag routes for the EVPN instance,
specifies the downstream label that the other PEs can use to send specifies the downstream label that the other PEs can use to send
unknown unicast, multicast or broadcast traffic for that EVPN unknown unicast, multicast or broadcast traffic for that EVPN
instance to this 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 12.2. 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 EVPN instance is advertised in the Inclusive Ethernet Tag particular EVPN instance is advertised in the Inclusive Ethernet Tag
Multicast route as described in section "Handling of Multi- Multicast route as described in section "Handling of Multi-
Destination 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
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same P2MP LSP, using upstream labels [VPLS-MCAST]. This is the same P2MP LSP, using upstream labels [VPLS-MCAST]. This is the
equivalent of an Aggregate Inclusive tree in [VPLS-MCAST]. When P2MP equivalent of an Aggregate Inclusive tree in [VPLS-MCAST]. When P2MP
LSPs are used for flooding unknown unicast traffic, packet re- LSPs are used for flooding unknown unicast traffic, packet re-
ordering is possible. 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 13. Forwarding Unicast Packets
This section describes procedures for forwarding unicast packets by This section describes procedures for forwarding unicast packets by
PEs, where such packets are received from either directly connected PEs, where such packets are received from either directly connected
CEs, or from some other PEs. CEs, or from some other PEs.
14.1. Forwarding packets received from a CE 13.1. 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
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P2MP LSP. If a distinct P2MP LSP is used for a given Ethernet Tag in P2MP LSP. If a distinct P2MP LSP is used for a given Ethernet Tag in
the EVPN instance, then only the PEs in the Ethernet Tag MUST be the the EVPN instance, then only the PEs in the Ethernet Tag MUST be the
leaves of the P2MP LSP. The packet MUST be encapsulated in the P2MP leaves of the P2MP LSP. The packet MUST be encapsulated in the P2MP
LSP label stack. 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 13.2. Forwarding packets received from a remote PE
This section described the procedures for forwarding known and This section described the procedures for forwarding known and
unknown unicast packets received from a remote PE. unknown unicast packets received from a remote PE.
14.2.1. Unknown Unicast Forwarding 13.2.1. 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 EVPN instance or in case of a P2MP LSP label associated with an EVPN instance or in case of
ingress replication the downstream label advertised in the P-Tunnel ingress replication the downstream label advertised in the P-Tunnel
attribute, and after performing the split horizon procedures attribute, and after performing the split horizon procedures
described in section "Split Horizon": described in section "Split Horizon":
- If the PE is the designated forwarder of BUM traffic on a - If the PE is the designated forwarder of BUM traffic on a
particular set of ESIs for the Ethernet Tag, the default behavior is particular set of ESIs for the Ethernet Tag, the default behavior is
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not required to perform a destination MAC address lookup. As an not required to perform a destination MAC address lookup. As an
option, the PE may perform a destination MAC lookup to flood the option, the PE may perform a destination MAC lookup to flood the
packet to only a subset of the CE interfaces in the Ethernet Tag. For packet to only a subset of the CE interfaces in the Ethernet Tag. For
instance the PE may decide to not flood an BUM packet on certain instance the PE may decide to not flood an BUM packet on certain
Ethernet segments even if it is the DF on the Ethernet segment, based Ethernet segments even if it is the DF on the Ethernet segment, based
on administrative policy. 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 13.2.2. Known Unicast Forwarding
If the top MPLS label ends up being an EVPN label that was advertised If the top MPLS label ends up being an EVPN label that was advertised
in the unicast MAC advertisements, then the PE either forwards the in the unicast MAC advertisements, then the PE either forwards the
packet based on CE next-hop forwarding information associated with packet based on CE next-hop forwarding information associated with
the label or does a destination MAC address lookup to forward the the label or does a destination MAC address lookup to forward the
packet to a CE. packet to a CE.
15. Load Balancing of Unicast Frames 14. 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 14.1. 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
routes for that ESI in order to determine the load-balancing routes for that ESI in order to determine the load-balancing
characteristics of the Ethernet segment. characteristics of the Ethernet segment.
15.1.1 Single-Active Redundancy Mode 14.1.1 Single-Active Redundancy Mode
For a given ESI, if the remote PE has imported an Ethernet A-D route For a given ES, if the remote PE has imported the set of Ethernet A-D
per Ethernet Segment from at least one PE, where the "Active-Standby" per ES routes from at least one PE, where the "Single-Active" flag in
flag in the ESI Label Extended Community is set, then the remote PE the ESI Label Extended Community is set, then the remote PE MUST
MUST deduce that the Ethernet segment is operating in Single-Active deduce that the ES is operating in Single-Active redundancy mode. As
redundancy mode. As such, the MAC address will be reachable only via such, the MAC address will be reachable only via the PE announcing
the PE announcing the associated MAC Advertisement route - this is the associated MAC Advertisement route - this is referred to as the
referred to as the primary PE. The set of other PE nodes advertising primary PE. The other PEs advertising the set of Ethernet A-D per ES
Ethernet A-D routes per Ethernet Segment for the same ESI serve as routes for the same ES provide backup paths for that ES, in case the
backup paths, in case the active PE encounters a failure. These are primary PE encounters a failure, and are referred to as backup PEs.
referred to as the backup PEs. It should be noted that the primary PE It should be noted that the primary PE for a given <ES, EVI> is the
for a given <ESI, EVI> is the DF for that <ESI, EVI>. DF for that <ES, EVI>.
If the primary PE encounters a failure, it MAY withdraw its Ethernet If the primary PE encounters a failure, it MAY withdraw its set of
A-D route for the affected segment prior to withdrawing the entire Ethernet A-D per ES routes for the affected ES prior to withdrawing
set of MAC Advertisement routes. it set of MAC Advertisement routes.
In the case where only a single other backup PE in the network had If there is only one backup PE for a given ES, the remote PE MAY use
advertised an Ethernet A-D route for the same ESI, the remote PE can the primary PE's withdrawal of its set of Ethernet A-D per ES routes
then use the Ethernet A-D route withdrawal as a trigger to update its as a trigger to update its forwarding entries, for the associated MAC
forwarding entries, for the associated MAC addresses, to point addresses, to point towards the backup PE. As the backup PE starts
towards the backup PE. As the backup PE starts learning the MAC learning the MAC addresses over its attached ES, it will start
addresses over its attached Ethernet segment, it will start sending sending MAC Advertisement routes while the failed PE withdraws its
MAC Advertisement routes while the failed PE withdraws its own. This routes. This mechanism minimizes the flooding of traffic during fail-
mechanism minimizes the flooding of traffic during fail-over events. over events.
In the case where multiple other backup PE in the network had If there is more than one backup PE for a given ES, the remote PE
advertised an Ethernet A-D route for the same ESI, the remote PE MUST MUST use the primary PE's withdrawal of its set of Ethernet A-D per
then use the Ethernet A-D route withdrawal as a trigger to start ES routes as a trigger to start flooding traffic for the associated
flooding traffic destined to the associated MAC addresses (as long as MAC addresses (as long as flooding of unknown unicast is
flooding of unknown unicast is administratively allowed). It is not administratively allowed), as it is not possible to select a single
possible to select a single backup path in this case. backup PE.
15.1.2 All-Active Redundancy Mode 14.1.2 All-Active Redundancy Mode
If for the given ESI, none of the Ethernet A-D routes per Ethernet For a given ES, if the remote PE has imported the set of Ethernet A-D
Segment imported by the remote PE have the "Active-Standby" flag set per ES routes from one or more PEs and none of them have the "Single-
in the ESI Label Extended Community, then the remote PE MUST treat Active" flag in the ESI Label Extended Community set, then the remote
the Ethernet segment as operating in All-Active redundancy mode. The PE MUST deduce that the ES is operating in All-Active redundancy
remote PE would then treat the MAC address as reachable via all of mode. A remote PE that receives a MAC advertisement route with non-
the PE nodes from which it has received both an Ethernet A-D route reserved ESI SHOULD consider the advertised MAC address to be
per Ethernet Segment as well as an Ethernet A-D route per EVI for the reachable via all PEs that have advertised reachability to that MAC
ESI in question. The remote PE MUST use the MAC advertisement and address' EVI/ES via the combination of an Ethernet A-D per EVI route
eligible Ethernet A-D routes to construct the set of next-hops that for that EVI/ES (and Ethernet Tag if applicable) AND an Ethernet A-D
it can use to send the packet to the destination MAC. Each next-hop per ES route for that ES. The remote PE MUST use received MAC
comprises an MPLS label stack that is to be used by the egress PE to Advertisement routes and Ethernet A-D per EVI/per ES routes to
forward the packet. This label stack is determined as follows: construct the set of next-hops for the advertised MAC address.
The remote PE MUST use the MAC advertisement and eligible Ethernet A-
D routes to construct the set of next-hops that it can use to send
the packet to the destination MAC. Each next-hop comprises an MPLS
label stack that is to be used by the egress PE to forward the
packet. This label stack is determined as follows:
-If the next-hop is constructed as a result of a MAC route then this -If the next-hop is constructed as a result of a MAC route then this
label stack MUST be used. However, if the MAC route doesn't exist, label stack MUST be used. However, if the MAC route doesn't exist,
then the next-hop and MPLS label stack is constructed as a result of then the next-hop and MPLS label stack is constructed as a result of
the Ethernet A-D routes. Note that the following description applies the Ethernet A-D routes. Note that the following description applies
to determining the label stack for a particular next-hop to reach a to determining the label stack for a particular next-hop to reach a
given PE, from which the remote PE has received and imported Ethernet given PE, from which the remote PE has received and imported Ethernet
A-D routes that have the matching ESI and Ethernet Tag as the one A-D routes that have the matching ESI and Ethernet Tag as the one
present in the MAC advertisement. The Ethernet A-D routes mentioned present in the MAC advertisement. The Ethernet A-D routes mentioned
in the following description refer to the ones imported from this in the following description refer to the ones imported from this
given PE. given PE.
-If an Ethernet A-D route per Ethernet Segment for that ESI exists, -If a set of Ethernet A-D per ES routes for that ES AND an Ethernet
together with an Ethernet A-D route per EVI, then the label from that A-D route per EVI exist, then the label from that latter route must
latter route must be used. be used.
The following example explains the above. The following example explains the above.
Consider a CE (CE1) that is dual-homed to two PEs (PE1 and PE2) on a Consider a CE (CE1) that is dual-homed to two PEs (PE1 and PE2) on a
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 (mapped to EVI1). A remote PE, say PE3, is able to learn that
via PE1 and PE2. Both PE1 and PE2 may advertise MAC1 in BGP if they MAC1 is reachable via PE1 and PE2. Both PE1 and PE2 may advertise
receive packets with MAC1 from CE1. If this is not the case, and if MAC1 in BGP if they receive packets with MAC1 from CE1. If this is
MAC1 is advertised only by PE1, PE3 still considers MAC1 as reachable not the case, and if MAC1 is advertised only by PE1, PE3 still
via both PE1 and PE2 as both PE1 and PE2 advertise a Ethernet A-D considers MAC1 as reachable via both PE1 and PE2 as both PE1 and PE2
route per ESI for ES1 as well as an Ethernet A-D route per EVI for advertise a set of Ethernet A-D per ES routes for ES1 as well as an
<ES1, VLAN1>. Ethernet A-D per EVI route for <EVI1, ES1>.
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 EVPN 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.
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send a particular packet to PE1, then PE3 can choose from multiple send a particular packet to PE1, then PE3 can choose from multiple
RSVP-TE LSPs that have PE1 as their destination. RSVP-TE LSPs that have PE1 as their destination.
When PE1 or PE2 receive the packet destined for CE1 from PE3, if the When PE1 or PE2 receive the packet destined for CE1 from PE3, if the
packet is a unicast MAC packet it is forwarded to CE1. If it is a packet is a unicast MAC packet it is forwarded to CE1. If it is a
multicast or broadcast MAC packet then only one of PE1 or PE2 must multicast or broadcast MAC packet then only one of PE1 or PE2 must
forward the packet to the CE. Which of PE1 or PE2 forward this packet forward the packet to the CE. Which of PE1 or PE2 forward this packet
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 set of
A-D routes, that had been previously advertised, for the Ethernet Ethernet A-D per ES routes that had been previously advertised for
Segment to the CE. When the MAC entry on the PE ages out, the PE MUST that ES. When the MAC entry on the PE ages out, the PE MUST withdraw
withdraw the MAC address from BGP. Note that to aid convergence, the the MAC address from BGP. Note that to aid convergence, the Ethernet
Ethernet Tag A-D routes MAY be withdrawn before the MAC routes. This Tag A-D routes MAY be withdrawn before the MAC routes. This enables
enables the remote PEs to remove the MPLS next-hop to this particular the remote PEs to remove the MPLS next-hop to this particular PE from
PE from the set of MPLS next-hops that can be used to forward traffic the set of MPLS next-hops that can be used to forward traffic to the
to the CE. For further details and procedures on withdrawal of EVPN CE. For further details and procedures on withdrawal of EVPN route
route types in the event of PE to CE failures please section "PE to types in the event of PE to CE failures please section "PE to CE
CE Network Failures". Network Failures".
15.2. Load balancing of traffic between an PE and a local CE 14.2. 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.
15.2.1. Data plane learning 14.2.1. Data plane learning
Consider that the PEs perform data plane learning for local MAC Consider that the PEs perform data plane learning for local MAC
addresses learned from local CEs. This enables the PE(s) to learn a addresses learned from local CEs. This enables the PE(s) to learn a
particular MAC address and associate it with one or more interfaces, particular MAC address and associate it with one or more interfaces,
if the technology between the PE and the CE supports multi-pathing. if the technology between the PE and the CE supports multi-pathing.
The PEs can now load balance traffic destined to that MAC address on The PEs can now load balance traffic destined to that MAC address on
the multiple interfaces. the multiple interfaces.
Whether the CE can load balance traffic that it generates on the Whether the CE can load balance traffic that it generates on the
multiple interfaces is dependent on the CE implementation. multiple interfaces is dependent on the CE implementation.
15.2.2. Control plane learning 14.2.2. 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 EVPN forwarding procedures to forward the traffic. employs EVPN forwarding procedures to forward the traffic.
16. MAC Mobility 15. 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.
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attached to the same multi-homed site. 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 15.1. MAC Duplication Issue
A situation may arise where the same MAC address is learned by A situation may arise where the same MAC address is learned by
different PEs in the same VLAN because of two (or more hosts) being different PEs in the same VLAN because of two (or more hosts) being
mis-configured with the same (duplicate) MAC address. In such mis-configured with the same (duplicate) MAC address. In such
situation, the traffic originating from these hosts would trigger situation, the traffic originating from these hosts would trigger
continuous MAC moves among the PEs attached to these hosts. It is continuous MAC moves among the PEs attached to these hosts. It is
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 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 traffic for the duplicate MAC address to one of the PEs advertising
the duplicate MAC address. the duplicate MAC address.
16.2. Sticky MAC addresses 15.2. Sticky MAC addresses
There are scenarios in which it is desired to configure some MAC There are scenarios in which it is desired to configure some MAC
addresses as static so that they are not subjected to MAC move. In addresses as static so that they are not subjected to MAC move. In
such scenarios, these MAC addresses are advertised with MAC Mobility such scenarios, these MAC addresses are advertised with MAC Mobility
Extended Community where static flag is set to 1 and sequence number 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 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 same MAC address(es) via local learning, then the PE MUST alert
the operator. the operator.
17. Multicast & Broadcast 16. Multicast & Broadcast
The PEs in a particular EVPN instance may use ingress replication or The PEs in a particular EVPN instance may use ingress replication or
P2MP LSPs to send multicast traffic to other PEs. P2MP LSPs to send multicast traffic to other PEs.
17.1. Ingress Replication 16.1. Ingress Replication
The PEs may use ingress replication for flooding BUM traffic as The PEs may use ingress replication for flooding BUM traffic as
described in section "Handling of Multi-Destination Traffic". A given described in section "Handling of Multi-Destination Traffic". A given
broadcast packet must be sent to all the remote PEs. However a given broadcast packet must be sent to all the remote PEs. However a given
multicast packet for a multicast flow may be sent to only a subset of multicast packet for a multicast flow may be sent to only a subset of
the PEs. Specifically a given multicast flow may be sent to only the PEs. Specifically a given multicast flow may be sent to only
those PEs that have receivers that are interested in the multicast those PEs that have receivers that are interested in the multicast
flow. Determining which of the PEs have receivers for a given flow. Determining which of the PEs have receivers for a given
multicast flow is done using explicit tracking described below. multicast flow is done using explicit tracking described below.
17.2. P2MP LSPs 16.2. P2MP LSPs
An PE may use an "Inclusive" tree for sending an BUM packet. This An PE may use an "Inclusive" tree for sending an BUM packet. This
terminology is borrowed from [VPLS-MCAST]. terminology 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. point-to-multipoint LSPs created by RSVP-TE or mLDP.
17.2.1. Inclusive Trees 16.2.1. 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 EVPN to carry all the multicast traffic from a specified set of EVPN
instances on a given PE. A particular P-Multicast tree can be set up instances on a given PE. A particular P-Multicast tree can be set up
to carry the traffic originated by sites belonging to a single EVPN to carry the traffic originated by sites belonging to a single EVPN
instance, or to carry the traffic originated by sites belonging to instance, or to carry the traffic originated by sites belonging to
different EVPN instances. The ability to carry the traffic of more different EVPN instances. The ability to carry the traffic of more
than one EVPN instance on the same tree is termed 'Aggregation'. The than one EVPN instance on the same tree is termed 'Aggregation'. The
tree needs to include every PE that is a member of any of the EVPN tree needs to include every PE that is a member of any of the EVPN
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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
EVPN instances on the same P2MP LSP using upstream labels. The EVPN instances on the same P2MP LSP using upstream labels. The
procedures for aggregation are the same as those described in [VPLS- procedures for aggregation are the same as those described in [VPLS-
MCAST], with VPLS A-D routes replaced by EVPN Inclusive Multicast MCAST], with VPLS A-D routes replaced by EVPN Inclusive Multicast
routes. routes.
18. Convergence 17. 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 17.1. 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 17.2. 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
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. PE to CE Network Failures 17.3. 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. Frame Ordering 18. Frame Ordering
In a MAC address, bit-1 of the most significant byte is used for In a MAC address, bit-1 of the most significant byte is used for
unicast/multicast indication and bit-2 is used for globally unique unicast/multicast indication and bit-2 is used for globally unique
versus locally administered MAC address. If the value of the 2nd versus locally administered MAC address. If the value of the 2nd
nibble (bits 4 thorough 8) of the most significant byte of the nibble (bits 4 thorough 8) of the most significant byte of the
destination MAC address (which follows the last MPLS label) happens destination MAC address (which follows the last MPLS label) happens
to be 0x4 or 0x6, then the Ethernet frame can be misinterpreted as an 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 IPv4 or IPv6 packet by intermediate P nodes performing ECMP based on
in load balancing packets belonging to the same flow on different deep packet inspection, thus resulting in load balancing packets
ECMP paths, thus subjecting them to different delays. Therefore, belonging to the same flow on different ECMP paths and subjecting
packets belonging to the same flow can arrive at the destination out them to different delays. Therefore, packets belonging to the same
of order. This out of order delivery can happen during steady state flow can arrive at the destination out of order. This out of order
in absence of any failures resulting in significant impact to the delivery can happen during steady state in absence of any failures
network operation. resulting in significant impact to the network operation.
In order to avoid any such mis-ordering, the usage of control word In order to avoid any such mis-ordering, the following rules are
SHALL adhere to the following rules: applied:
- A PE MUST use the control world when sending EVPN encapsulated - If a network uses deep packet inspection for its ECMP, then the
packets over a MP2P or a P2P LSP control word SHOULD be used when sending EVPN encapsulated packets
over a MP2P LSP.
- A PE MUST NOT use the control world when sending EVPN encapsulated - If a network uses Entropy label [RFC6790], then the control word
packets over a P2MP LSP SHOULD NOT be used when sending EVPN encapsulated packet over a MP2P
LSP.
- When sending EVPN encapsulated packets over a P2MP LSP or TE P2P
LSP, then the control world SHOULD NOT be used.
The control word is defined as follows: The control word is defined as follows:
0 1 2 3 0 1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0| Reserved | Sequence Number | |0 0 0 0| Reserved | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In the above diagram the first 4 bits MUST be set to 0. The rest of In the above diagram the first 4 bits MUST be set to 0. The rest of
the first 16 bits are reserved for future use. They MUST be set to 0 the first 16 bits are reserved for future use. They MUST be set to 0
when transmitting, and MUST be ignored upon receipt. The next 16 bits when transmitting, and MUST be ignored upon receipt. The next 16 bits
provide a sequence number that MUST also be set to zero by default. provide a sequence number that MUST also be set to zero by default.
20. Acknowledgements 19. Acknowledgements
Special thanks to Yakov Rekhter for reviewing this draft several Special thanks to Yakov Rekhter for reviewing this draft several
times and providing valuable comments and for his very engaging times and providing valuable comments and for his very engaging
discussions on several topics of this draft that helped shape this discussions on several topics of this draft that helped shape this
document. We would also like to thank Pedro Marques, Kaushik Ghosh, 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 We would like to thank Jorge Rabadan for his contribution to section
improve several sections of this draft. 5 of this draft. We like to thank Thomas Morin for his review of this
draft and his contribution of section 8.6. Last but not least, many
thanks to Jakob Heitz for his help to improve several sections of
this draft.
21. Security Considerations 20. Security Considerations
Security considerations discussed in [RFC4761] and [RFC4762] apply to
this document for MAC learning in data-plane over an Attachment
Circuit (AC) and for flooding of unknown unicast and ARP messages
over the MPLS/IP core. Security considerations discussed in [RFC4364]
apply to this document for MAC learning in control-plane over the
MPLS/IP core. This section describes additional considerations.
As mentioned in [RFC4761], there are two aspects to achieving data
privacy and protecting against denial-of-service attacks in a VPN:
securing the control plane and protecting the forwarding path.
Compromise of the control plane could result in a PE sending customer
data belonging to some EVPN to another EVPN, or black-holing EVPN
customer data, or even sending it to an eavesdropper; none of which
are acceptable from a data privacy point of view. In addition,
compromise of the control plane could result in black-holing EVPN
customer data and could provide opportunities for unauthorized EVPN
data usage (e.g., exploiting traffic replication within a multicast
tree to amplify a denial-of-service attack based on sending large
amounts of traffic).
The mechanisms in this document use BGP for the control plane. Hence,
techniques such as in [RFC5925] help authenticate BGP messages,
making it harder to spoof updates (which can be used to divert EVPN
traffic to the wrong EVPN instance) or withdrawals (denial-of-service
attacks). In the multi-AS methods (b) and (c), this also means
protecting the inter-AS BGP sessions, between the ASBRs, the PEs, or
the Route Reflectors.
Note that [RFC5925] will not help in keeping MPLS labels private --
knowing the labels, one can eavesdrop on EVPN traffic. However, this
requires access to the data path within an SP network, which is
assumed to be composed of trusted nodes/links.
One of the requirements for protecting the data plane is that the
MPLS labels be accepted only from valid interfaces. For a PE, valid
interfaces comprise links from other routers in the PE's own AS. For
an ASBR, valid interfaces comprise links from other routers in the
ASBR's own AS, and links from other ASBRs in ASes that have instances
of a given EVPN. It is especially important in the case of multi-AS
EVPN instances that one accept EVPN packets only from valid
interfaces.
It is also important to help limit malicious traffic into a network
for an imposter MAC address. The mechanism described in section 16.1,
shows how duplicate MAC addresses can be detected and continous false
MAC mobility can be prevented. The mechanism described in section
16.2, shows how MAC addresses can be pinned to a given Ethernet
Segment, such that if they appear behind any other Ethernet Segments,
the traffic for those MAC addresses be prevented from entering the
EVPN network from the other Ethernet Segments.
21. Contributors
In addition to the authors listed above, the following individuals
also contributed to this document:
Samer Salam
Sami Boutros
Keyur Patel
Clarence Filsfils
Dennis Cai
Cisco
Ravi Shekhar
Quaizar Vohra
Kireeti Kompella
Apurva Mehta
Nadeem Mohammad
Juniper Networks
Florin Balus
Nuage Networks
22. IANA Considerations 22. IANA Considerations
23. References
This document defines a new NLRI, called "EVPN", to be carried in BGP
using multiprotocol extensions. This NLRI uses the existing AFI of
25 (L2VPN). IANA has assigned it a SAFI value of 70.
23. References
23.1 Normative References 23.1 Normative References
[RFC4364] "BGP/MPLS IP VPNs", Rosen, Rekhter, et. al., February 2006 [RFC4364] "BGP/MPLS IP VPNs", Rosen, Rekhter, et. al., February 2006
[RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service [RFC4761] Kompella, K. and Y. Rekhter, "Virtual Private LAN Service
(VPLS) Using BGP for Auto-Discovery and Signaling", RFC (VPLS) Using BGP for Auto-Discovery and Signaling", RFC
4761, January 2007. 4761, January 2007.
[RFC4762] Lasserre, M. and V. Kompella, "Virtual Private LAN Service [RFC4762] Lasserre, M. and V. Kompella, "Virtual Private LAN Service
(VPLS) Using Label Distribution Protocol (LDP) Signaling", (VPLS) Using Label Distribution Protocol (LDP) Signaling",
skipping to change at page 45, line 39 skipping to change at page 48, line 37
[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-04.txt, July Ethernet VPN", draft-ietf-l2vpn-evpn-req-04.txt, July
2013. 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-14.txt, July 2013. 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.
[RFC6790] K. Kompella et. al, "The Use of Entropy Labels in MPLS
Forwarding", RFC 6790, November 2012.
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
skipping to change at page 46, line 23 skipping to change at page 49, line 23
AT&T AT&T
200 S. Laurel Avenue 200 S. Laurel Avenue
Middletown, NJ 07748 Middletown, NJ 07748
USA USA
Email: uttaro@att.com Email: uttaro@att.com
Nabil Bitar Nabil Bitar
Verizon Communications Verizon Communications
Email : nabil.n.bitar@verizon.com Email : nabil.n.bitar@verizon.com
Ravi Shekhar
Juniper Networks
1194 N. Mathilda Ave.
Sunnyvale, CA 94089 US
Email: rshekhar@juniper.net
Florin Balus
Alcatel-Lucent
e-mail: Florin.Balus@alcatel-lucent.com
Keyur Patel
Cisco
170 West Tasman Drive
San Jose, CA 95134, US
Email: keyupate@cisco.com
Sami Boutros
Cisco
170 West Tasman Drive
San Jose, CA 95134, US
Email: sboutros@cisco.com
Samer Salam
Cisco
Email: ssalam@cisco.com
John Drake John Drake
Juniper Networks Juniper Networks
Email: jdrake@juniper.net Email: jdrake@juniper.net
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