BFD for VXLAN
draft-spallagatti-bfd-vxlan-01

Internet Engineering Task Force                       S. Pallagatti, Ed.
Internet-Draft                                                   B. Saji
Intended status: Standards Track                             S. Paragiri
Expires: January 7, 2016                                Juniper Networks
                                                             V. Govindan
                                                            M. Mudigonda
                                                                   Cisco
                                                               G. Mirsky
                                                                Ericsson
                                                            July 6, 2015

                             BFD for VXLAN
                     draft-spallagatti-bfd-vxlan-01

Abstract

   This document describes use of Bidirectional Forwarding Detection
   (BFD) protocol for VXLAN . Comments on this draft should be directed
   to nvo3@ietf.org, rtg-bfd@ietf.org.

Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

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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   This Internet-Draft will expire on January 7, 2016.

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Copyright Notice

   Copyright (c) 2015 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
   (http://trustee.ietf.org/license-info) in effect on the date of
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Use cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Deployment  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  BFD Packet Encapsulation  . . . . . . . . . . . . . . . . . .   5
   5.  Reception of BFD packet . . . . . . . . . . . . . . . . . . .   5
     5.1.  Demux of the BFD packet . . . . . . . . . . . . . . . . .   6
   6.  Echo BFD  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   6
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   11. Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   "Virtual eXtensible Local Area Network (VXLAN)" has been defined in
   [RFC7348] that provides an encapsulation scheme which allows VM's to
   communicate in data centre network.

   VXLAN is typically deployed in data centres on virtualized hosts,
   which may be spread across multiple racks.  The individual racks may
   be parts of a different Layer 3 network or they could be in a single
   Layer 2 network.  The VXLAN segments/overlay networks are overlaid on
   top of these Layer 2 or Layer 3 networks.

   A VM can communicate with a VM in other host only if they are on same
   VXLAN.  VM's are unaware of VXLAN tunnels as VXLAN tunnel terminates
   on VTEP (hypervisor/TOR).  VTEP (hypervisor/TOR) are responsible for
   encapsulating and decapsulating frames sent from VM's.

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   Since underlay is a L3 network, connectivity check for these tunnels
   becomes important.  BFD as defined in [RFC5880] can be used to
   monitor the VXLAN tunnels.

   This draft addresses requirements outlined in
   [I-D.ashwood-nvo3-operational-requirement].  Specifically with
   reference to the OAM model to Figure 3 of
   [I-D.ashwood-nvo3-operational-requirement], this draft outlines
   proposal to implement the OAM mechanism between the NV Edges using
   BFD.

2.  Use cases

   Main use case of BFD for VXLAN is for tunnel connectivity check.
   There are other use cases such as

      Layer 2 VM's:

         Most deployments will have VM's with only L2 capabilities and
         may not understand L3.  BFD being a L3 protocol can be used for
         tunnel connectivity check, where BFD will start and terminate
         at the NV Edge (VTEPs).

         It is possible to aggregate the connectivity checks for
         multiple tenants by running a BFD session between the VTEPs
         over VxLAN tunnel.  In rest of this document terms NV Edge and
         VTEP are used interchangeably.

      Fault localization:

         It is also possible that VM's are L3 aware and can possibly
         host a BFD session.  In these cases BFD sessions can be
         established between VM's for connectivity check.  In addition a
         BFD session can be established between VTEPs for tunnel
         connectivity check.  Having a hierarchical OAM model helps
         localize faults.

      Service node reachability:

         Service node is responsible for sending BUM traffic.  In case
         of service node tunnel terminates at VTEP and it might not even
         host VM's.  If TOR's/Hypervisor wants to check service node
         reachability then it would like run BFD session over VXLAN
         tunnel to service node.

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3.  Deployment

      +------------+-------------+
      |        Server 1          |
      |                          |
      | +----+----+  +----+----+ |
      | |VM1-1    |  |VM1-2    | |
      | |VNI 100  |  |VNI 200  | |
      | |         |  |         | |
      | +---------+  +---------+ |
      | Hypervisor VTEP (IP1)    |
      +--------------------------+
                            |
                            |
                            |
                            |   +-------------+
                            |   |   Layer 3   |
                            |---|   Network   |
                                |             |
                                +-------------+
                                    |
                                    |
                                    +-----------+
                                                |
                                                |
                                         +------------+-------------+
                                         |    Hypervisor VTEP (IP2) |
                                         | +----+----+  +----+----+ |
                                         | |VM2-1    |  |VM2-2    | |
                                         | |VNI 100  |  |VNI 200  | |
                                         | |         |  |         | |
                                         | +---------+  +---------+ |
                                         |      Server 2            |
                                         +--------------------------+

                                 Figure 1

   Figure 1 illustrates a scenario where we have two servers, each of
   them hosting two VMs.  These VTEPs terminate two VXLAN tunnels with
   VNI number 100 and 200 between them.  Separate BFD sessions can be
   established between the VTEPs (IP1 and IP2) for monitoring each of
   the VXLAN tunnels (VNI 100 and 200).  No BFD packet intended to
   Hypervisor VTEP should be forwarded to VM's as VM's may drop this
   leading to false negative.  This method is also applicable VTEP which
   are either software or physical device.

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4.  BFD Packet Encapsulation

   VxLAN packet format has been defined in Section 5 of [RFC7348].  The
   Outer IP/UDP and VXLAN headers MUST be encoded by the sender as per
   [RFC7348].

   If VTEP is equipped with GPE header capitalises and decides to use
   GPE instead of VXLAN then GPE header MUST be encoded as per
   Section 3.3 of [I-D.quinn-vxlan-gpe].  Next Protocol Field in GPE
   header MUST be set to IPv4 or IPv6.

   Details of how VTEP decides to use VXLAN or GPE header is outside the
   scope of this document.

   The BFD packet MUST be carried inside the inner MAC frame of the
   VxLAN packet.  The inner MAC frame carrying the BFD payload has the
   following format:

      Ethernet Header:

         Destination MAC: This MUST be a well-known MAC [TBD] OR the MAC
         address of the destination VTEP.  The details of how the
         destination MAC address is obtained is outside the scope of
         this document.

         Source MAC: MAC address of the originating VTEP

      IP header:

         Source IP: IP address of the originating VTEP.

         Destination IP: IP address of the terminating VTEP.

         TTL: This MUST be set to 1.  This is to ensure that the BFD
         packet is not routed within the L3 underlay network.

         Note: Inner source and destination IP needs more discussion in
         WG.

      The fields of the UDP header and the BFD control packet are
      encoded as specified in RFC 5881.

5.  Reception of BFD packet

   Once a packet is received, VTEP MUST validate the packet as described
   in Section 4.1 of [RFC7348].  If the Destination MAC of the inner MAC
   frame matches the well-known MAC or the MAC address of the VTEP the
   packet MUST be processed further.

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   The UDP destination port and the TTL of the inner MAC frame MUST be
   validated to determine if the received packet can be processed by
   BFD.  BFD packet with inner MAC set to VTEP or well-known MAC address
   MUST not be forwarded to VM's.

5.1.  Demux of the BFD packet

   Demux of IP BFD packet has been defined in Section 3 of [RFC5881].
   Since multiple BFD sessions may be running between two VTEPs, there
   needs to be a mechanism for demultiplexing received BFD packets to
   the proper session.  The procedure for demultiplexing packets with
   Your Discriminator = 0 is different from [RFC5880].  For such
   packets, the BFD session is identified using the VNID, the source IP
   and the destination IP of the packet.  If BFD packet is received with
   non-zero your discriminator then BFD session should be demultiplexed
   only with your discriminator as the key.

6.  Echo BFD

   Support for echo BFD is outside the scope of this document.

7.  IANA Considerations

   The well-known MAC to be used for the Destination MAC address of the
   inner MAC frame needs to be defined

8.  Security Considerations

   Document recommends setting of inner IP TTL to 1 which could lead to
   DDoS attack, implementation MUST have throttling in place.
   Throttling MAY be relaxed for BFD packeted based on port number.

   Other than inner IP TTL set to 1 this specification does not raise
   any additional security issues beyond those of the specifications
   referred to in the list of normative references.

9.  Contributors

   Reshad Rahman
   rrahman@cisco.com
   Cisco

10.  Acknowledgements

   Authors would like to thank Jeff Hass of Juniper Networks for his
   reviews and feedback on this material.

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11.  Normative References

   [I-D.ashwood-nvo3-operational-requirement]
              Ashwood-Smith, P., Iyengar, R., Tsou, T., Sajassi, A.,
              Boucadair, M., Jacquenet, C., and M. Daikoku, "NVO3
              Operational Requirements", draft-ashwood-nvo3-operational-
              requirement-03 (work in progress), July 2013.

   [I-D.ietf-bfd-seamless-base]
              Akiya, N., Pignataro, C., Ward, D., Bhatia, M., and J.
              Networks, "Seamless Bidirectional Forwarding Detection
              (S-BFD)", draft-ietf-bfd-seamless-base-05 (work in
              progress), June 2015.

   [I-D.quinn-vxlan-gpe]
              Quinn, P., Manur, R., Kreeger, L., Lewis, D., Maino, F.,
              Smith, M., Agarwal, P., Yong, L., Xu, X., Elzur, U., Garg,
              P., and D. Melman, "Generic Protocol Extension for VXLAN",
              draft-quinn-vxlan-gpe-04 (work in progress), February
              2015.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, June 2010.

   [RFC5881]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD) for IPv4 and IPv6 (Single Hop)", RFC 5881, June
              2010.

   [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, August 2014.

Authors' Addresses

   Santosh Pallagatti (editor)
   Juniper Networks
   Embassy Business Park
   Bangalore, KA  560093
   India

   Email: santoshpk@juniper.net

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   Basil Saji
   Juniper Networks
   Embassy Business Park
   Bangalore, KA  560093
   India

   Email: sbasil@juniper.net

   Sudarsan Paragiri
   Juniper Networks
   1194 N. Mathilda Ave.
   Sunnyvale, California  94089-1206
   USA

   Email: sparagiri@juniper.net

   Vengada Prasad Govindan
   Cisco

   Email: venggovi@cisco.com

   Mallik Mudigonda
   Cisco

   Email: mmudigon@cisco.com

   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com

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