BFD for Geneve
draft-ietf-nvo3-bfd-geneve-02

Document Type Active Internet-Draft (nvo3 WG)
Authors Xiao Min  , Greg Mirsky  , Santosh Pallagatti  , Jeff Tantsura 
Last updated 2021-03-10
Replaces draft-xiao-nvo3-bfd-geneve
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NVO3 Working Group                                                X. Min
Internet-Draft                                                 G. Mirsky
Intended status: Standards Track                               ZTE Corp.
Expires: September 11, 2021                                S. Pallagatti
                                                                  VMware
                                                             J. Tantsura
                                                        Juniper Networks
                                                          March 10, 2021

                             BFD for Geneve
                     draft-ietf-nvo3-bfd-geneve-02

Abstract

   This document describes the use of the Bidirectional Forwarding
   Detection (BFD) protocol in point-to-point Generic Network
   Virtualization Encapsulation (Geneve) tunnels used to make up an
   overlay network.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 11, 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must

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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions Used in This Document . . . . . . . . . . . . . .   3
     2.1.  Abbreviations . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   3.  BFD Packet Transmission over Geneve Tunnel  . . . . . . . . .   3
     3.1.  BFD Encapsulation With Inner Ethernet/IP/UDP Header . . .   3
     3.2.  BFD Encapsulation With Inner IP/UDP Header  . . . . . . .   5
   4.  Reception of BFD packet from Geneve Tunnel  . . . . . . . . .   7
     4.1.  Demultiplexing of the BFD packet  . . . . . . . . . . . .   8
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   "Generic Network Virtualization Encapsulation" (Geneve) [RFC8926]
   provides an encapsulation scheme that allows building an overlay
   network by decoupling the address space of the attached virtual hosts
   from that of the network.

   This document describes the use of Bidirectional Forwarding Detection
   (BFD) protocol [RFC5880] to enable monitoring continuity of the path
   between two Geneve tunnel endpoints, which may be NVE (Network
   Virtualization Edge) or other device acting as a Geneve tunnel
   endpoint.  Specifically, the asynchronous mode of BFD, as defined in
   [RFC5880], is used to monitor a p2p Geneve tunnel, and support for
   BFD Echo function is outside the scope of this document.  For
   simplicity, in this document, NVE is used to represent Geneve tunnel
   endpoint, TS (Tenant System) is used to represent the physical or
   virtual device attached to a Geneve tunnel endpoint from the outside.
   VAP (Virtual Access Point) is the NVE side of the interface between
   the NVE and the TS, and a VAP is a logical network port (virtual or
   physical) into a specific virtual network.  For detailed definitions
   and descriptions of NVE, TS and VAP, please refer to [RFC7365] and
   [RFC8014].

   The use cases and the deployment of BFD for Geneve are consistent
   with what's described in Section 1 and 3 of [RFC8971] ("Bidirectional

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   Forwarding Detection (BFD) for Virtual eXtensible Local Area Network
   (VXLAN)"), except for the usage of Management VNI, which in the case
   of Geneve is described in [I-D.ietf-nvo3-geneve-oam], and outside the
   scope of this document.  The major difference between Geneve and
   VXLAN [RFC7348] is that Geneve supports multi-protocol payload and
   variable length options.

2.  Conventions Used in This Document

2.1.  Abbreviations

   BFD: Bidirectional Forwarding Detection

   EVPN: Ethernet Virtual Private Networks

   Geneve: Generic Network Virtualization Encapsulation

   NVE: Network Virtualization Edge

   TS: Tenant System

   VAP: Virtual Access Point

   VNI: Virtual Network Identifier

   VXLAN: Virtual eXtensible Local Area Network

2.2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  BFD Packet Transmission over Geneve Tunnel

   Concerning whether the Geneve data packets include an Ethernet frame
   or an IP packet, this document defines two formats of BFD packet
   encapsulation in Geneve.  BFD session is originated and terminated at
   VAP of an NVE, selection of the BFD packet encapsulation is based on
   how the VAP encapsulates the data packets.

3.1.  BFD Encapsulation With Inner Ethernet/IP/UDP Header

   If the VAP that originates the BFD packets is used to encapsulate
   Ethernet data frames, then BFD packets are encapsulated in Geneve as
   described below.  The Geneve packet format over IPv4 is defined in

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   Section 3.1 of [RFC8926].  The Geneve packet format over IPv6 is
   defined in Section 3.2 of [RFC8926].  The Outer IP/UDP and Geneve
   headers MUST be encoded by the sender as defined in [RFC8926].  Note
   that the outer IP header and the inner IP header may not be of the
   same address family, in other words, outer IPv6 header accompanied
   with inner IPv4 header and outer IPv4 header accompanied with inner
   IPv6 header are both possible.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                      Outer Ethernet Header                    ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        Outer IPvX Header                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        Outer UDP Header                       ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                          Geneve Header                        ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                      Inner Ethernet Header                    ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        Inner IPvX Header                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         Inner UDP Header                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        BFD Control Packet                     ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Outer Ethernet FCS                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 1: Geneve Encapsulation of BFD Control Packet With the Inner
                          Ethernet/IP/UDP Header

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   The BFD packet MUST be carried inside the inner Ethernet frame of the
   Geneve packet.  The inner Ethernet frame carrying the BFD Control
   packet has the following format:

      Ethernet Header:

         Source MAC: MAC address of a VAP of the originating NVE.

         Destination MAC: MAC address of a VAP of the terminating NVE.

      IP Header:

         Source IP: IP address of a VAP of the originating NVE.  If the
         VAP of the originating NVE has no IP address, then the IP
         address 0.0.0.0 for IPv4 or ::/128 for IPv6 MUST be used.

         Destination IP: IP address of a VAP of the terminating NVE.  If
         the VAP of the terminating NVE has no IP address, then the IP
         address 127.0.0.1 for IPv4 or ::1/128 for IPv6 MUST be used.

         TTL or Hop Limit: MUST be set to 255 in accordance with
         [RFC5881].

      The fields of the UDP header and the BFD Control packet are
      encoded as specified in [RFC5881].

   When the BFD packets are encapsulated in Geneve in this way, the
   Geneve header defined in [RFC8926] follows the value set below.

      Opt Len field SHOULD be set to 0, which indicates there isn't any
      variable length option.

      O bit MUST be set to 1, which indicates this packet contains a
      control message.

      C bit MUST be set to 0, which indicates there isn't any critical
      option.

      Protocol Type field MUST be set to 0x6558 (Ethernet frame).

      Virtual Network Identifier (VNI) field SHOULD be set to the VNI
      number that the originating VAP is mapped to.

3.2.  BFD Encapsulation With Inner IP/UDP Header

   If the VAP that originates the BFD packets is used to encapsulate IP
   data packets, then BFD packets are encapsulated in Geneve as
   described below.  The Geneve packet format over IPv4 is defined in

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   Section 3.1 of [RFC8926].  The Geneve packet format over IPv6 is
   defined in Section 3.2 of [RFC8926].  The Outer IP/UDP and Geneve
   headers MUST be encoded by the sender as defined in [RFC8926].  Note
   that the outer IP header and the inner IP header may not be of the
   same address family, in other words, outer IPv6 header accompanied
   with inner IPv4 header and outer IPv4 header accompanied with inner
   IPv6 header are both possible.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         Ethernet Header                       ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        Outer IPvX Header                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        Outer UDP Header                       ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                          Geneve Header                        ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        Inner IPvX Header                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         Inner UDP Header                      ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                        BFD Control Packet                     ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               FCS                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Figure 2: Geneve Encapsulation of BFD Control Packet With the Inner
                               IP/UDP Header

   The BFD packet MUST be carried inside the inner IP packet of the
   Geneve packet.  The inner IP packet carrying the BFD Control packet
   has the following format:

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      IP header:

         Source IP: IP address of a VAP of the originating NVE.

         Destination IP: IP address of a VAP of the terminating NVE.

         TTL or Hop Limit: MUST be set to 255 in accordance with
         [RFC5881].

      The fields of the UDP header and the BFD Control packet are
      encoded as specified in [RFC5881].

   When the BFD packets are encapsulated in Geneve in this way, the
   Geneve header defined in [RFC8926] follows the value set below.

      Opt Len field SHOULD be set to 0, which indicates there isn't any
      variable length option.

      O bit MUST be set to 1, which indicates this packet contains a
      control message.

      C bit MUST be set to 0, which indicates there isn't any critical
      option.

      Protocol Type field MUST be set to 0x0800 (IPv4) or 0x86DD (IPv6),
      depending on the address family of the inner IP packet.

      Virtual Network Identifier (VNI) field SHOULD be set to the VNI
      number that the originating VAP is mapped to.

4.  Reception of BFD packet from Geneve Tunnel

   Once a packet is received, the NVE MUST validate the packet as
   described in [RFC8926].

      If the Protocol Type field equals 0x6558 (Ethernet frame), and the
      Destination MAC of the inner Ethernet frame matches the MAC
      address of a VAP which is mapped to the same as received VNI, then
      the Destination IP, the UDP destination port and the TTL or Hop
      Limit of the inner IP packet MUST be validated to determine
      whether the received packet can be processed by BFD.

      If the Protocol Type field equals 0x0800 (IPv4) or 0x86DD (IPv6),
      and the Destination IP of the inner IP packet matches the IP
      address of a VAP which is mapped to the same as received VNI, then
      the UDP destination port and the TTL or Hop Limit of the inner IP
      packet MUST be validated to determine whether the received packet
      can be processed by BFD.

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4.1.  Demultiplexing of the BFD packet

   In BFD over Geneve, a BFD session is originated and terminated at
   VAP, usually one NVE owns multiple VAPs, so multiple BFD sessions may
   be running between two NVEs, there needs to be a mechanism for
   demultiplexing received BFD packets to the proper session.
   Furthermore, due to the fact that [RFC8014] allows for N-to-1 mapping
   between VAP and VNI at one NVE, multiple BFD sessions between two
   NVEs for the same VNI are allowed.  Also note that a BFD session can
   only be established between two VAPs that are mapped to the same VNI
   and use the same way to encapsulate data packets.

   If the BFD packet is received with Your Discriminator equals to 0,
   for different BFD encapsulation, the procedure for demultiplexing the
   received BFD packets is different.

      When the BFD Encapsulation With Inner Ethernet/IP/UDP Header is
      used, the BFD session MUST be identified using the VNI number, and
      the inner Ethernet/IP/UDP Header, i.e., the source MAC, the source
      IP, the destination MAC, the destination IP, and the source UDP
      port number present in the inner Ethernet/IP/UDP header.

      When the BFD Encapsulation With Inner IP/UDP Header is used, the
      BFD session MUST be identified using the VNI number, and the inner
      IP/UDP header, i.e., the source IP, the destination IP, and the
      source UDP port number present in the inner IP/UDP header.

   If the BFD packet is received with non-zero Your Discriminator, then
   the BFD session MUST be demultiplexed only with Your Discriminator as
   the key.  The exchange of BFD discriminators may be achieved by echo
   request/reply, EVPN, etc.  The detailed mechanism on how to exchange
   the BFD discriminators is outside the scope of this document.

5.  Security Considerations

   This document does not raise any additional security issues beyond
   those of the specifications referred to in the list of references.

6.  IANA Considerations

   This document has no IANA action requested.

7.  Acknowledgements

   The authors would like to acknowledge Reshad Rahman, Jeffrey Haas and
   Matthew Bocci for their guidance on this work.

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   The authors would like to acknowledge David Black for his explanation
   on the mapping relation between VAP and VNI.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881,
              DOI 10.17487/RFC5881, June 2010,
              <https://www.rfc-editor.org/info/rfc5881>.

   [RFC7365]  Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
              Rekhter, "Framework for Data Center (DC) Network
              Virtualization", RFC 7365, DOI 10.17487/RFC7365, October
              2014, <https://www.rfc-editor.org/info/rfc7365>.

   [RFC8014]  Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
              Narten, "An Architecture for Data-Center Network
              Virtualization over Layer 3 (NVO3)", RFC 8014,
              DOI 10.17487/RFC8014, December 2016,
              <https://www.rfc-editor.org/info/rfc8014>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8926]  Gross, J., Ed., Ganga, I., Ed., and T. Sridhar, Ed.,
              "Geneve: Generic Network Virtualization Encapsulation",
              RFC 8926, DOI 10.17487/RFC8926, November 2020,
              <https://www.rfc-editor.org/info/rfc8926>.

8.2.  Informative References

   [I-D.ietf-nvo3-geneve-oam]
              Mirsky, G., Boutros, S., Black, D., and S. Pallagatti,
              "OAM for use in GENEVE", draft-ietf-nvo3-geneve-oam-01
              (work in progress), November 2020.

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   [RFC7348]  Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
              L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
              eXtensible Local Area Network (VXLAN): A Framework for
              Overlaying Virtualized Layer 2 Networks over Layer 3
              Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
              <https://www.rfc-editor.org/info/rfc7348>.

   [RFC8971]  Pallagatti, S., Ed., Mirsky, G., Ed., Paragiri, S.,
              Govindan, V., and M. Mudigonda, "Bidirectional Forwarding
              Detection (BFD) for Virtual eXtensible Local Area Network
              (VXLAN)", RFC 8971, DOI 10.17487/RFC8971, December 2020,
              <https://www.rfc-editor.org/info/rfc8971>.

Authors' Addresses

   Xiao Min
   ZTE Corp.
   Nanjing
   China

   Phone: +86 25 88013062
   Email: xiao.min2@zte.com.cn

   Greg Mirsky
   ZTE Corp.
   USA

   Email: gregimirsky@gmail.com

   Santosh Pallagatti
   VMware

   Email: santosh.pallagatti@gmail.com

   Jeff Tantsura
   Juniper Networks

   Email: jefftant.ietf@gmail.com

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