draft-ietf-bfd-vxlan-03.txt   draft-ietf-bfd-vxlan-04.txt 
Internet Engineering Task Force S. Pallagatti, Ed. BFD S. Pallagatti, Ed.
Internet-Draft Rtbrick Internet-Draft Rtbrick
Intended status: Standards Track S. Paragiri Intended status: Standards Track S. Paragiri
Expires: April 11, 2019 Juniper Networks Expires: May 27, 2019 Juniper Networks
V. Govindan V. Govindan
M. Mudigonda M. Mudigonda
Cisco Cisco
G. Mirsky G. Mirsky
ZTE Corp. ZTE Corp.
October 8, 2018 November 23, 2018
BFD for VXLAN BFD for VXLAN
draft-ietf-bfd-vxlan-03 draft-ietf-bfd-vxlan-04
Abstract Abstract
This document describes the use of the Bidirectional Forwarding This document describes the use of the Bidirectional Forwarding
Detection (BFD) protocol in Virtual eXtensible Local Area Network Detection (BFD) protocol in Virtual eXtensible Local Area Network
(VXLAN) overlay networks. (VXLAN) overlay networks.
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
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 11, 2019. This Internet-Draft will expire on May 27, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
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. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Use cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Deployment . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Deployment . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. BFD Packet Transmission over VXLAN Tunnel . . . . . . . . . . 5 5. BFD Packet Transmission over VXLAN Tunnel . . . . . . . . . . 5
5.1. BFD Packet Encapsulation in VXLAN . . . . . . . . . . . . 6 5.1. BFD Packet Encapsulation in VXLAN . . . . . . . . . . . . 6
6. Reception of BFD packet from VXLAN Tunnel . . . . . . . . . . 7 6. Reception of BFD packet from VXLAN Tunnel . . . . . . . . . . 7
6.1. Demultiplexing of the BFD packet . . . . . . . . . . . . 7 6.1. Demultiplexing of the BFD packet . . . . . . . . . . . . 7
7. Use of reserved VNI . . . . . . . . . . . . . . . . . . . . . 8 7. Use of reserved VNI . . . . . . . . . . . . . . . . . . . . . 8
8. Echo BFD . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. Echo BFD . . . . . . . . . . . . . . . . . . . . . . . . . . 8
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. Security Considerations . . . . . . . . . . . . . . . . . . . 8 10. Security Considerations . . . . . . . . . . . . . . . . . . . 8
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 9
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9
13. Normative References . . . . . . . . . . . . . . . . . . . . 9 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 13.1. Normative References . . . . . . . . . . . . . . . . . . 9
13.2. Informational References . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
"Virtual eXtensible Local Area Network" (VXLAN) [RFC7348]. provides "Virtual eXtensible Local Area Network" (VXLAN) [RFC7348]. provides
an encapsulation scheme that allows virtual machines (VMs) to an encapsulation scheme that allows building an overlay network by
communicate in a data center network. decoupling the address space of the attached virtual hosts from that
of the network.
VXLAN is typically deployed in data centers interconnecting VXLAN is typically deployed in data centers interconnecting
virtualized hosts, which may be spread across multiple racks. The virtualized hosts of a tenant. VXLAN addresses requirements of the
individual racks may be part of a different Layer 3 network, or they Layer 2 and Layer 3 data center network infrastructure in the
could be in a single Layer 2 network. The VXLAN segments/overlays presence of VMs in a multi-tenant environment, discussed in section 3
are overlaid on top of Layer 3 network. [RFC7348], by providing Layer 2 overlay scheme on a Layer 3 network.
A VM can communicate with another VM only if they are on the same In the absence of a router in the overlay, a VM can communicate with
VXLAN segment. VMs are unaware of VXLAN tunnels as a VXLAN tunnel is another VM only if they are on the same VXLAN segment. VMs are
terminated on a VXLAN Tunnel End Point (VTEP) (hypervisor/TOR). unaware of VXLAN tunnels as a VXLAN tunnel is terminated on a VXLAN
VTEPs (hypervisor/TOR) are responsible for encapsulating and Tunnel End Point (VTEP) (hypervisor/TOR). VTEPs (hypervisor/TOR) are
decapsulating frames exchanged among VMs. responsible for encapsulating and decapsulating frames exchanged
among VMs.
Ability to monitor path continuity, i.e., perform proactive Ability to monitor path continuity, i.e., perform proactive
continuity check (CC) for these tunnels, is important. The continuity check (CC) for these tunnels, is important. The
asynchronous mode of BFD, as defined in [RFC5880], can be used to asynchronous mode of BFD, as defined in [RFC5880], can be used to
monitor a VXLAN tunnel. Use of [I-D.ietf-bfd-multipoint] is for monitor a VXLAN tunnel. Use of [I-D.ietf-bfd-multipoint] is for
future study. future study.
Also, BFD in VXLAN can be used to monitor the particular service Also, BFD in VXLAN can be used to monitor the particular service
nodes that are designated to properly handle Layer 2 broadcast, nodes that are designated to handle Layer 2 broadcast properly,
unknown unicast, and multicast traffic. Such nodes, often referred unknown unicast, and multicast traffic. Such nodes, discussed in
"replicators", are usually virtual VTEPs and can be monitored by details in [RFC8293], are often referred to as "replicators", are
physical VTEPs to minimize BUM traffic directed to the unavailable usually virtual VTEPs and can be monitored by physical VTEPs to
replicator. minimize BUM traffic directed to the unavailable replicator.
This document describes the use of Bidirectional Forwarding Detection This document describes the use of Bidirectional Forwarding Detection
(BFD) protocol VXLAN to enable monitoring continuity of the path (BFD) protocol VXLAN to enable monitoring continuity of the path
between Network Virtualization Edges (NVEs) and/or availability of a between Network Virtualization Edges (NVEs) and/or availability of a
replicator service node using BFD. replicator service node using BFD.
In this document, the terms NVE and VTEP are used interchangeably. In this document, the terms NVE and VTEP are used interchangeably.
2. Conventions used in this document 2. Conventions used in this document
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The primary use case of BFD for VXLAN is for continuity check of a The primary use case of BFD for VXLAN is for continuity check of a
tunnel. By exchanging BFD control packets between VTEPs, an operator tunnel. By exchanging BFD control packets between VTEPs, an operator
exercises the VXLAN path in both the underlay and overlay thus exercises the VXLAN path in both the underlay and overlay thus
ensuring the VXLAN path availability and VTEPs reachability. BFD ensuring the VXLAN path availability and VTEPs reachability. BFD
failure detection can be used for maintenance. There are other use failure detection can be used for maintenance. There are other use
cases such as the following: cases such as the following:
Layer 2 VMs: Layer 2 VMs:
Most deployments will have VMs with only L2 capabilities that Deployments might have VMs with only L2 capabilities and not
may not support L3. BFD being an L3 protocol can be used as a have an IP address assigned or, in other cases, VMs are
assigned IP address but are restricted to communicate only
within their subnet. BFD being an L3 protocol can be used as a
tunnel CC mechanism, where BFD will start and terminate at the tunnel CC mechanism, where BFD will start and terminate at the
NVEs, e.g., VTEPs. NVEs, e.g., VTEPs.
It is possible to aggregate the CC sessions for multiple It is possible to aggregate the CC sessions for multiple
tenants by running a BFD session between the VTEPs over VxLAN tenants by running a BFD session between the VTEPs over VxLAN
tunnel. tunnel.
Fault localization: Fault localization:
It is also possible that VMs are L3 aware and can host a BFD It is also possible that VMs are L3 aware and can host a BFD
session. In these cases, BFD sessions can be established among session. In these cases, BFD sessions can be established among
VMs for CC. Also, BFD sessions can be created among VTEPs for VMs for CC. Also, BFD sessions can be created among VTEPs for
tunnel CC. Having a hierarchical OAM model helps localize tunnel CC. Having a hierarchical OAM model helps localize
faults though it requires additional consideration. faults though it requires additional consideration of, for
example, coordination of BFD intervals across the OAM layers
Service node reachability: Service node reachability:
The service node is responsible for sending BUM traffic. In The service node is responsible for sending BUM traffic. In
case a service node tunnel terminates at a VTEP, and that VTEP case a service node tunnel terminates at a VTEP, and that VTEP
might not even host VM. BFD session between TOR/hypervisor and might not even host VM. BFD session between TOR/hypervisor and
service node can be used to monitor service node reachability. service node can be used to monitor service node reachability.
4. Deployment 4. 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 VNI number 100 and 200 respectively. Separate BFD tunnels with VNI number 100 and 200 respectively. Separate BFD
sessions can be established between the VTEPs (IP1 and IP2) for sessions can be established between the VTEPs (IP1 and IP2) for
monitoring each of the VXLAN tunnels (VNI 100 and 200). No BFD monitoring each of the VXLAN tunnels (VNI 100 and 200). The
packets intended for a Hypervisor VTEP should be forwarded to a VM as implementation SHOULD have a reasonable upper bound on the number of
a VM may drop BFD packets leading to a false negative. This method BFD sessions that can be created between the same pair of VTEPs. No
is applicable whether the VTEP is a virtual or physical device. BFD packets intended for a Hypervisor VTEP should 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 | |
| | | | | | | | | | | |
| +---------+ +---------+ | | +---------+ +---------+ |
| Hypervisor VTEP (IP1) | | Hypervisor VTEP (IP1) |
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associated with the VNI. associated with the VNI.
6.1. Demultiplexing of the BFD packet 6.1. 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. The procedure for demultiplexing packets to the proper session. The procedure for demultiplexing
packets with Your Discriminator equal to 0 is different from packets with Your Discriminator equal to 0 is different from
[RFC5880]. For such packets, the BFD session MUST be identified [RFC5880]. For such packets, the BFD session MUST be identified
using the inner headers, i.e., the source IP and the destination IP using the inner headers, i.e., the source IP, the destination IP, and
present in the IP header carried by the payload of the VXLAN the source UDP port number present in the IP header carried by the
encapsulated packet. The VNI of the packet SHOULD be used to derive payload of the VXLAN encapsulated packet. The VNI of the packet
interface-related information for demultiplexing the packet. If BFD SHOULD be used to derive interface-related information for
packet is received with non-zero Your Discriminator, then BFD session demultiplexing the packet. If BFD packet is received with non-zero
MUST be demultiplexed only with Your Discriminator as the key. Your Discriminator, then BFD session MUST be demultiplexed only with
Your Discriminator as the key.
7. Use of reserved VNI 7. Use of reserved VNI
BFD session MAY be established for the reserved VNI 0. One way to In most cases, a single BFD session is sufficient for the given VTEP
aggregate BFD sessions between VTEP's is to establish a BFD session to monitor the reachability of a remote VTEP, regardless of the
with VNI 0. A VTEP MAY also use VNI 0 to establish a BFD session number of VNIs in common. When the single BFD session is used to
with a service node. monitor reachability of the remote VTEP, an implementation SHOULD use
a VNI of 0.
8. Echo BFD 8. Echo BFD
Support for echo BFD is outside the scope of this document. Support for echo BFD is outside the scope of this document.
9. IANA Considerations 9. IANA Considerations
IANA has assigned TBA as a dedicated MAC address from the IANA 8-bit IANA has assigned TBA as a dedicated MAC address from the IANA 8-bit
unicast MAC address registry to be used as the Destination MAC unicast MAC address registry to be used as the Destination MAC
address of the inner Ethernet of VXLAN when carrying BFD control address of the inner Ethernet of VXLAN when carrying BFD control
packets. packets.
10. Security Considerations 10. Security Considerations
The document requires setting the inner IP TTL to 1 which could be The document requires setting the inner IP TTL to 1 which could be
used as a DDoS attack vector. Thus the implementation MUST have used as a DDoS attack vector. Thus the implementation MUST have
throttling in place to control the rate of BFD control packets sent throttling in place to control the rate of BFD control packets sent
to the control plane. Throttling MAY be relaxed for BFD packets to the control plane. Throttling MAY be relaxed for BFD packets
based on port number. based on port number.
Other than inner IP TTL set to 1 this specification does not raise The implementation SHOULD have a reasonable upper bound on the number
any additional security issues beyond those of the specifications of BFD sessions that can be created between the same pair of VTEPs.
Other than inner IP TTL set to 1 and limit the number of BFD sessions
between the same pair of VTEPs, this specification does not raise any
additional security issues beyond those of the specifications
referred to in the list of normative references. referred to in the list of normative references.
11. Contributors 11. Contributors
Reshad Rahman Reshad Rahman
rrahman@cisco.com rrahman@cisco.com
Cisco Cisco
12. Acknowledgments 12. Acknowledgments
Authors would like to thank Jeff Hass of Juniper Networks for his Authors would like to thank Jeff Hass of Juniper Networks for his
reviews and feedback on this material. reviews and feedback on this material.
Authors would also like to thank Nobo Akiya, Marc Binderberger, Authors would also like to thank Nobo Akiya, Marc Binderberger,
Shahram Davari and Donald E. Eastlake 3rd for the extensive reviews Shahram Davari, Donald E. Eastlake 3rd, and Anoop Ghanwani for the
and the most detailed and helpful comments. extensive reviews and the most detailed and helpful comments.
13. Normative References 13. References
13.1. Normative References
[I-D.ietf-bfd-multipoint] [I-D.ietf-bfd-multipoint]
Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD for Katz, D., Ward, D., Networks, J., and G. Mirsky, "BFD for
Multipoint Networks", draft-ietf-bfd-multipoint-18 (work Multipoint Networks", draft-ietf-bfd-multipoint-18 (work
in progress), June 2018. in progress), June 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 9, line 46 skipping to change at page 10, line 9
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3 Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014, Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>. <https://www.rfc-editor.org/info/rfc7348>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
13.2. Informational References
[RFC8293] Ghanwani, A., Dunbar, L., McBride, M., Bannai, V., and R.
Krishnan, "A Framework for Multicast in Network
Virtualization over Layer 3", RFC 8293,
DOI 10.17487/RFC8293, January 2018,
<https://www.rfc-editor.org/info/rfc8293>.
Authors' Addresses Authors' Addresses
Santosh Pallagatti (editor) Santosh Pallagatti (editor)
Rtbrick Rtbrick
Email: santosh.pallagatti@gmail.com Email: santosh.pallagatti@gmail.com
Sudarsan Paragiri Sudarsan Paragiri
Juniper Networks Juniper Networks
1194 N. Mathilda Ave. 1194 N. Mathilda Ave.
Sunnyvale, California 94089-1206 Sunnyvale, California 94089-1206
USA USA
Email: sparagiri@juniper.net Email: sparagiri@juniper.net
Vengada Prasad Govindan Vengada Prasad Govindan
Cisco Cisco
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