draft-ietf-bfd-vxlan-09.txt   draft-ietf-bfd-vxlan-10.txt 
BFD S. Pallagatti, Ed. BFD S. Pallagatti, Ed.
Internet-Draft VMware Internet-Draft VMware
Intended status: Standards Track S. Paragiri Intended status: Standards Track S. Paragiri
Expires: June 1, 2020 Individual Contributor Expires: July 11, 2020 Individual Contributor
V. Govindan V. Govindan
M. Mudigonda M. Mudigonda
Cisco Cisco
G. Mirsky G. Mirsky
ZTE Corp. ZTE Corp.
November 29, 2019 January 8, 2020
BFD for VXLAN BFD for VXLAN
draft-ietf-bfd-vxlan-09 draft-ietf-bfd-vxlan-10
Abstract Abstract
This document describes the use of the Bidirectional Forwarding This document describes the use of the Bidirectional Forwarding
Detection (BFD) protocol in point-to-point Virtual eXtensible Local Detection (BFD) protocol in point-to-point Virtual eXtensible Local
Area Network (VXLAN) tunnels forming up an overlay network. Area Network (VXLAN) tunnels used to form an overlay network.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 1, 2020. This Internet-Draft will expire on July 11, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3 2.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
3. Deployment . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Deployment . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. BFD Packet Transmission over VXLAN Tunnel . . . . . . . . . . 5 4. BFD Packet Transmission over VXLAN Tunnel . . . . . . . . . . 6
5. Reception of BFD Packet from VXLAN Tunnel . . . . . . . . . . 7 5. Reception of BFD Packet from VXLAN Tunnel . . . . . . . . . . 8
5.1. Demultiplexing of the BFD Packet . . . . . . . . . . . . 8 5.1. Demultiplexing of the BFD Packet . . . . . . . . . . . . 9
6. Use of the Specific VNI . . . . . . . . . . . . . . . . . . . 8 6. Use of the Specific VNI . . . . . . . . . . . . . . . . . . . 9
7. Echo BFD . . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. Echo BFD . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 10
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
12.1. Normative References . . . . . . . . . . . . . . . . . . 9 12.1. Normative References . . . . . . . . . . . . . . . . . . 10
12.2. Informational References . . . . . . . . . . . . . . . . 10 12.2. Informational References . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
"Virtual eXtensible Local Area Network" (VXLAN) [RFC7348] provides an "Virtual eXtensible Local Area Network" (VXLAN) [RFC7348] provides an
encapsulation scheme that allows building an overlay network by encapsulation scheme that allows building an overlay network by
decoupling the address space of the attached virtual hosts from that decoupling the address space of the attached virtual hosts from that
of the network. of the network.
One use of VXLAN is in data centers interconnecting virtual machines One use of VXLAN is in data centers interconnecting virtual machines
(VMs) of a tenant. VXLAN addresses requirements of the Layer 2 and (VMs) of a tenant. VXLAN addresses requirements of the Layer 2 and
skipping to change at page 3, line 8 skipping to change at page 3, line 8
hypervisors. However, the concepts are equally applicable to non- hypervisors. However, the concepts are equally applicable to non-
virtualized hosts attached to VTEPs in switches. virtualized hosts attached to VTEPs in switches.
In the absence of a router in the overlay, a VM can communicate with In the absence of a router in the overlay, a VM can communicate with
another VM only if they are on the same VXLAN segment. VMs are another VM only if they are on the same VXLAN segment. VMs are
unaware of VXLAN tunnels as a VXLAN tunnel is terminated on a VTEP. unaware of VXLAN tunnels as a VXLAN tunnel is terminated on a VTEP.
VTEPs are responsible for encapsulating and decapsulating frames VTEPs are responsible for encapsulating and decapsulating frames
exchanged among VMs. exchanged among VMs.
Ability to monitor path continuity, i.e., perform proactive The ability to monitor path continuity, i.e., perform proactive
continuity check (CC) for point-to-point (p2p) VXLAN tunnels, is continuity check (CC) for point-to-point (p2p) VXLAN tunnels, is
important. The asynchronous mode of BFD, as defined in [RFC5880], is important. The asynchronous mode of BFD, as defined in [RFC5880], is
used to monitor a p2p VXLAN tunnel. used to monitor a p2p VXLAN tunnel.
In the case where a Multicast Service Node (MSN) (as described in In the case where a Multicast Service Node (MSN) (as described in
Section 3.3 of [RFC8293]) resides behind a Network Virtualization Section 3.3 of [RFC8293]) resides behind a Network Virtualization
Endpoint (NVE), the mechanisms described in this document apply and Endpoint (NVE), the mechanisms described in this document apply and
can, therefore, be used to test the connectivity from the source NVE can, therefore, be used to test the connectivity from the source NVE
to the MSN. to the MSN.
skipping to change at page 4, line 14 skipping to change at page 4, line 14
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
3. Deployment 3. Deployment
Figure 1 illustrates the scenario with two servers, each of them Figure 1 illustrates the scenario with two servers, each of them
hosting two VMs. The servers host VTEPs that terminate two VXLAN hosting two VMs. The servers host VTEPs that terminate two VXLAN
tunnels with VXLAN Network Identifier (VNI) number 100 and 200 tunnels with VXLAN Network Identifier (VNI) number 100 and 200
respectively. Separate BFD sessions can be established between the respectively. Separate BFD sessions can be established between the
VTEPs (IP1 and IP2) for monitoring each of the VXLAN tunnels (VNI 100 VTEPs (IP1 and IP2) for monitoring each of the VXLAN tunnels (VNI 100
and 200). An implementation that supports this specification MUST be and 200). Using a BFD session to monitor a set of VXLAN VNIs between
able to control the number of BFD sessions that can be created the same pair of VTEPs might help to detect and localize problems
between the same pair of VTEPs. BFD packets intended for a VTEP MUST caused by misconfiguration. An implementation that supports this
NOT be forwarded to a VM as a VM may drop BFD packets leading to a specification MUST be able to control the number of BFD sessions that
false negative. This method is applicable whether the VTEP is a can be created between the same pair of VTEPs. BFD packets intended
virtual or physical device. for a VTEP MUST NOT be forwarded to a VM, as a VM may drop BFD
packets, leading to a false negative. This method is applicable
whether the VTEP is a virtual or physical device.
+------------+-------------+ +------------+-------------+
| Server 1 | | Server 1 |
| +----+----+ +----+----+ | | +----+----+ +----+----+ |
| |VM1-1 | |VM1-2 | | | |VM1-1 | |VM1-2 | |
| |VNI 100 | |VNI 200 | | | |VNI 100 | |VNI 200 | |
| | | | | | | | | | | |
| +---------+ +---------+ | | +---------+ +---------+ |
| VTEP (IP1) | | VTEP (IP1) |
+--------------------------+ +--------------------------+
skipping to change at page 5, line 6 skipping to change at page 5, line 35
| |VM2-1 | |VM2-2 | | | |VM2-1 | |VM2-2 | |
| |VNI 100 | |VNI 200 | | | |VNI 100 | |VNI 200 | |
| | | | | | | | | | | |
| +---------+ +---------+ | | +---------+ +---------+ |
| Server 2 | | Server 2 |
+--------------------------+ +--------------------------+
Figure 1: Reference VXLAN Domain Figure 1: Reference VXLAN Domain
At the same time, a service layer BFD session may be used between the At the same time, a service layer BFD session may be used between the
tenants of VTEPs IP1 and IP2 to provide end-to-end fault management. tenants of VTEPs IP1 and IP2 to provide end-to-end fault management
In such case, for VTEPs BFD Control packets of that session are (this use case is outside the scope of this document). In such case,
indistinguishable from data packets. for VTEPs BFD Control packets of that session are indistinguishable
from data packets.
As per Section 4, the inner destination IP address SHOULD be set to For BFD Control packets encapsulated in VXLAN (Figure 2), the inner
one of the loopback addresses (127/8 range for IPv4 and destination IP address SHOULD be set to one of the loopback addresses
0:0:0:0:0:FFFF:7F00:0/104 range for IPv6). There could be a firewall from 127/8 range for IPv4 or to one of IPv4-mapped IPv4 loopback
configured on VTEP to block loopback addresses if set as the addresses from ::ffff:127.0.0.0/104 range for IPv6. There could be a
firewall configured on VTEP to block loopback addresses if set as the
destination IP in the inner IP header. It is RECOMMENDED to allow destination IP in the inner IP header. It is RECOMMENDED to allow
addresses from the loopback range through a firewall only if it is addresses from the loopback range through a firewall only if they are
used as the destination IP address in the inner IP header, and the used as the destination IP addresses in the inner IP header and the
destination UDP port is set to 3784 [RFC5881]. destination UDP port is set to 3784 [RFC5881].
4. BFD Packet Transmission over VXLAN Tunnel 4. BFD Packet Transmission over VXLAN Tunnel
BFD packet MUST be encapsulated and sent to a remote VTEP as BFD packets MUST be encapsulated and sent to a remote VTEPs as
explained in this section. Implementations SHOULD ensure that the explained in this section. Implementations SHOULD ensure that the
BFD packets follow the same lookup path as VXLAN data packets within BFD packets follow the same forwarding path as VXLAN data packets
the sender system. within the sender system.
BFD packets are encapsulated in VXLAN as described below. The VXLAN BFD packets are encapsulated in VXLAN as described below. The VXLAN
packet format is defined in Section 5 of [RFC7348]. The Outer IP/UDP packet format is defined in Section 5 of [RFC7348]. The Outer IP/UDP
and VXLAN headers MUST be encoded by the sender as defined in and VXLAN headers MUST be encoded by the sender as defined in
[RFC7348]. [RFC7348].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
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| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ Inner UDP Header ~ ~ Inner UDP Header ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
~ BFD Control Packet ~ ~ BFD Control Packet ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| FCS | | Outer FCS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: VXLAN Encapsulation of BFD Control Packet Figure 2: VXLAN Encapsulation of BFD Control Packet
The BFD packet MUST be carried inside the inner Ethernet frame of the The BFD packet MUST be carried inside the inner Ethernet frame of the
VXLAN packet. The choice of Destination MAC and Destination IP VXLAN packet. The choice of Destination MAC and Destination IP
addresses for the inner Ethernet frame MUST ensure that the BFD addresses for the inner Ethernet frame MUST ensure that the BFD
Control packet is not forwarded to a tenant but is processed locally Control packet is not forwarded to a tenant but is processed locally
at the remote VTEP. The inner Ethernet frame carrying the BFD at the remote VTEP. The inner Ethernet frame carrying the BFD
Control packet- has the following format: Control packet- has the following format:
Ethernet Header: Ethernet Header:
Destination MAC: This MUST NOT be of one of tenant's MAC Destination MAC: This MUST NOT be of one of tenant's MAC
addresses. The destination MAC address MAY be the address addresses. The destination MAC address MAY be the address
associated with the destination VTEP. The MAC address MAY be associated with the destination VTEP. The MAC address may be
configured, or it MAY be learned via a control plane protocol. either configured or learned via a control plane protocol. The
The details of how the MAC address is obtained are outside the details of how the MAC address is obtained are outside the
scope of this document. scope of this document.
Source MAC: MAC address associated with the originating VTEP Source MAC: MAC address associated with the originating VTEP
IP header: IP header:
Destination IP: IP address MUST NOT be of one of tenant's IP Destination IP: IP address MUST NOT be of one of tenant's IP
addresses. The IP address SHOULD be selected from the range addresses. The IP address SHOULD be selected from the range
127/8 for IPv4, for IPv6 - from the range 127/8 for IPv4, for IPv6 - from the range ::ffff:127.0.0.0/104.
0:0:0:0:0:FFFF:7F00:0/104. Alternatively, the destination IP Alternatively, the destination IP address MAY be set to VTEP's
address MAY be set to VTEP's IP address. IP address.
Source IP: IP address of the originating VTEP. Source IP: IP address of the originating VTEP.
TTL or Hop Limit: MUST be set to 1 to ensure that the BFD TTL or Hop Limit: MUST be set to 1 to ensure that the BFD
packet is not routed within the Layer 3 underlay network. This packet is not routed within the Layer 3 underlay network. This
addresses the scenario when the inner IP destination address is addresses the scenario when the inner IP destination address is
of VXLAN gateway and there is a router in underlay which of the VXLAN gateway and there is a router in the underlay
removes the VXLAN header, then it is possible to route the which removes the VXLAN header, then it is possible to route
packet as VXLAN gateway address is routable address. the packet as VXLAN gateway address is routable address.
The fields of the UDP header and the BFD Control packet are The fields of the UDP header and the BFD Control packet are
encoded as specified in [RFC5881]. encoded as specified in [RFC5881].
5. Reception of BFD Packet from VXLAN Tunnel 5. Reception of BFD Packet from VXLAN Tunnel
Once a packet is received, VTEP MUST validate the packet. If the Once a packet is received, the VTEP MUST validate the packet. If the
Destination MAC of the inner Ethernet frame matches one of the MAC Destination MAC of the inner Ethernet frame matches one of the MAC
addresses associated with the VTEP the packet MUST be processed addresses associated with the VTEP the packet MUST be processed
further. If the Destination MAC of the inner Ethernet frame doesn't further. If the Destination MAC of the inner Ethernet frame doesn't
match any of VTEP's MAC addresses, then the processing of the match any of VTEP's MAC addresses, then the processing of the
received VXLAN packet MUST follow the procedures described in received VXLAN packet MUST follow the procedures described in
Section 4.1 [RFC7348]. If the BFD session is using the Management Section 4.1 of [RFC7348]. If the BFD session is using the Management
VNI (Section 6), BFD Control packets with unknown MAC address MUST VNI (Section 6), BFD Control packets with unknown MAC address MUST
NOT be forwarded to VMs. NOT be forwarded to VMs.
The UDP destination port and the TTL of the inner IP packet MUST be The UDP destination port and the TTL or Hop Limit of the inner IP
validated to determine if the received packet can be processed by packet MUST be validated to determine if the received packet can be
BFD. processed by BFD.
5.1. Demultiplexing of the BFD Packet 5.1. Demultiplexing of the BFD Packet
Demultiplexing of IP BFD packet has been defined in Section 3 of Demultiplexing of IP BFD packet has been defined in Section 3 of
[RFC5881]. Since multiple BFD sessions may be running between two [RFC5881]. Since multiple BFD sessions may be running between two
VTEPs, there needs to be a mechanism for demultiplexing received BFD VTEPs, there needs to be a mechanism for demultiplexing received BFD
packets to the proper session. For demultiplexing packets with Your packets to the proper session. For demultiplexing packets with Your
Discriminator equal to 0, a BFD session MUST be identified using the Discriminator equal to 0, a BFD session MUST be identified using the
logical link over which the BFD Control packet is received. In the logical link over which the BFD Control packet is received. In the
case of VXLAN, the VNI number identifies that logical link. If BFD case of VXLAN, the VNI number identifies that logical link. If BFD
packet is received with non-zero Your Discriminator, then BFD session packet is received with non-zero Your Discriminator, then the BFD
MUST be demultiplexed only with Your Discriminator as the key. session MUST be demultiplexed only with Your Discriminator as the
key.
6. Use of the Specific VNI 6. Use of the Specific VNI
In most cases, a single BFD session is sufficient for the given VTEP In most cases, a single BFD session is sufficient for the given VTEP
to monitor the reachability of a remote VTEP, regardless of the to monitor the reachability of a remote VTEP, regardless of the
number of VNIs. When the single BFD session is used to monitor the number of VNIs. When the single BFD session is used to monitor the
reachability of the remote VTEP, an implementation SHOULD choose any reachability of the remote VTEP, an implementation SHOULD choose any
of the VNIs. An implementation MAY support the use of the Management of the VNIs. An implementation MAY support the use of the Management
VNI as control and management channel between VTEPs. The selection VNI as control and management channel between VTEPs. The selection
of the VNI number of the Management VNI MUST be controlled through of the VNI number of the Management VNI MUST be controlled through
skipping to change at page 8, line 42 skipping to change at page 9, line 43
Support for echo BFD is outside the scope of this document. Support for echo BFD is outside the scope of this document.
8. IANA Considerations 8. IANA Considerations
This specification has no IANA action requested. This section may be This specification has no IANA action requested. This section may be
deleted before the publication. deleted before the publication.
9. Security Considerations 9. Security Considerations
The document requires setting the inner IP TTL to 1, which could be The document requires setting the inner IP TTL or Hop Limit to 1,
used as a DDoS attack vector. Thus the implementation MUST have which could be used as a DDoS attack vector. Thus the implementation
throttling in place to control the rate of BFD Control packets sent MUST have throttling in place to control the rate of BFD Control
to the control plane. On the other hand, over-aggressive throttling packets sent to the control plane. On the other hand, over-
of BFD Control packets may become the cause of the inability to form aggressive throttling of BFD Control packets may become the cause of
and maintain BFD session at scale. Hence, throttling of BFD Control the inability to form and maintain BFD session at scale. Hence,
packets SHOULD be adjusted to permit BFD to work according to its throttling of BFD Control packets SHOULD be adjusted to permit BFD to
procedures. work according to its procedures.
This document recommends using an address from the Internal host This document recommends using an address from the Internal host
loopback addresses (127/8 range for IPv4 and loopback addresses 127/8 range for IPv4 or an IP4-mapped IPv4
0:0:0:0:0:FFFF:7F00:0/104 range for IPv6) as the destination IP loopback address from ::ffff:127.0.0.0/104 range for IPv6 as the
address in the inner IP header. Using such address prevents the destination IP address in the inner IP header. Using such an address
forwarding of the encapsulated BFD control message by a transient prevents the forwarding of the encapsulated BFD control message by a
node in case the VXLAN tunnel is broken as according to [RFC1812]: transient node in case the VXLAN tunnel is broken as according to
[RFC1812]:
A router SHOULD NOT forward, except over a loopback interface, any A router SHOULD NOT forward, except over a loopback interface, any
packet that has a destination address on network 127. A router packet that has a destination address on network 127. A router
MAY have a switch that allows the network manager to disable these MAY have a switch that allows the network manager to disable these
checks. If such a switch is provided, it MUST default to checks. If such a switch is provided, it MUST default to
performing the checks. performing the checks.
If the implementation supports establishing multiple BFD sessions If the implementation supports establishing multiple BFD sessions
between the same pair of VTEPs, there SHOULD be a mechanism to between the same pair of VTEPs, there SHOULD be a mechanism to
control the maximum number of such sessions that can be active at the control the maximum number of such sessions that can be active at the
same time. same time.
Other than inner IP TTL set to 1 and limit the number of BFD sessions Other than setting the value of inner IP TTL or Hop Limit to 1 and
between the same pair of VTEPs, this specification does not raise any limit the number of BFD sessions between the same pair of VTEPs, this
additional security issues beyond those of the specifications specification does not raise any additional security issues beyond
referred to in the list of normative references. those discussed in [RFC5880], [RFC5881], and [RFC7348].
10. Contributors 10. Contributors
Reshad Rahman Reshad Rahman
rrahman@cisco.com rrahman@cisco.com
Cisco Cisco
11. Acknowledgments 11. Acknowledgments
Authors would like to thank Jeff Haas of Juniper Networks for his Authors would like to thank Jeff Haas of Juniper Networks for his
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