Internet Engineering Task Force                       S. Pallagatti, Ed.
Internet-Draft                                               S. Paragiri
Intended status: Standards Track                                 B. Saji
Expires: November 5, 2015                               Juniper Networks
                                                             May 4, 2015


                             BFD for VXLAN
                     draft-spallagatti-bfd-vxlan-00

Abstract

   This document describes use of Bidirectional Forwarding Detection
   (BFD) protocol for VXLAN . Comments on this draft should be directed
   to nvo3@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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   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 November 5, 2015.

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
   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   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.  Use cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Deployment  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Packet Format . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Transmission of BFD Packet: . . . . . . . . . . . . . . . . .   6
   6.  Reception of BFD Packet:  . . . . . . . . . . . . . . . . . .   7
     6.1.  Demux of BFD Packet:  . . . . . . . . . . . . . . . . . .   7
   7.  Echo BFD: . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   8.  S-BFD:  . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     8.1.  Transmission of S-BFD:  . . . . . . . . . . . . . . . . .   8
     8.2.  Reception of S-BFD: . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   10. Security Considerations . . . . . . . . . . . . . . . . . . .   8
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   12. Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

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).  VETP (hypervisor/TOR) are responsible for
   encapsulating and decapsulating frames sent from VM's.

   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.






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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 aware and may not
         understand L3.  BFD being a L3 protocol can be used for tunnel
         connectivity check, where BFD will start and terminate at VTEP
         on different host.

      Fault localization:

         It is also possible that VM's are L3 aware and can possible
         host a BFD session.  In these cases BFD session can be used to
         run between VM's for VM's connectivity check, also BFD session
         between VTEP's for tunnel connectivity check.  With both VM's
         BFD session and tunnel BFD can easily localize the fault to
         either VM or tunnel.

      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.

3.  Deployment





















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      +------------+-------------+
      |        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            |
                                         +--------------------------+


   Consider the above diagram, where we have two servers with IP1 and
   IP2 and each of them are hosting two VM's.  There are two VXLAN
   tunnels with VNI number 100 and 200.  For connectivity check of these
   two VXLAN tunnels, BFD sessions needs to be established per tunnel.
   In the diagram above two BFD will be established between server 1's
   Hypervisor VTEP (IP1) and server2 Hypervisor VTEP(IP2).  BFD session
   will originate from Hypervisor VTEP (IP1) and terminate at Hypervisor
   VTEP (IP2) and visa versa.  Each BFD session on Hypervisor VTEP will
   be identified by its VNI in VXLAN header.  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.  Packet Format

   Packet format has been defined in Section 5 of [RFC7348].  Outer IP/
   UDP and VXLAN header will remain same and they should be filled by
   sending VTEP as per [RFC7348].  Inner packet format has been defined
   as below for BFD packet which terminates at VETP.  BFD packet MUST
   have a inner IP/UDP header followed by BFD payload.

       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

      Inner IPv4 Header:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Version|  IHL  |Type of Service|          Total Length         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Identification        |Flags|      Fragment Offset    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  TTL = 1      |Protocl=17(UDP)|   Header Checksum             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Inner Source IPv4 Address               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |       Inner Destination Ipv4 Address  = 127/8 address         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Inner IPv6 Header:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Version| Traffic Class |           Flow Label                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |         Payload Length        | NxtHdr=17(UDP)| Hop Limit = 1 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                     Inner Source IPv6 Address                 +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                                                               |
      +                  Inner Destination IPv6 Address  =            +
      |                  0:0:0:0:0:FFFF:7F00/104                      |
      +                                                               +
      |                                                               |
      +                                                               +



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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Inner UDP Header:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Source Port         |       Dest Port = 3784        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           UDP Length          |        UDP Checksum           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      BFD packet:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Vers |  Diag   |Sta|P|F|C|A|D|M|  Detect Mult  |    Length     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       My Discriminator                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Your Discriminator                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                    Desired Min TX Interval                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   Required Min RX Interval                    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                 Required Min Echo RX Interval                 |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

5.  Transmission of BFD Packet:

   This section describes BFD packet encapsulation while transmitting
   BFD packet from VTEP

      Outer IP/UDP and VXLAN header:

         VETP which is transmitting the packet MUST encapsulate the BFD
         packet in outer IP/UDP and VXLAN header as described in
         Section 5 of [RFC7348].  IP TOS value MUST be set to
         "Internetwork Control".

      Inner IP/UDP header:

         Srouce IP address:

            MUST be set to outgoing interface of sending VTEP interface.

         Destination IP address:





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            MUST be set to non-routable 127/8 or 0:0:0:0:0:FFFF:7F00/104
            range address.

         IP TTL/HOP LIMIT:

            MUST be set to 1.

         UDP header:

            UDP header is set as defined in Section 4 of [RFC5881]

      BFD Packet:

         BFD packet SHOULD be constructed as defined in Section 4 of
         [RFC5880].

6.  Reception of BFD Packet:

   Once a packet is received VTEP MUST validate packet as described in
   Section 4.1 of [RFC7348].  Since inner IP TTL is set to 1 packet
   SHOULD be consumed by VTEP and should not be forwarded further to VM.
   It is recommended that BFD packets should not be throttled with TTL
   1.  Implementation MAY have a check to relax throttling if the inner
   IP address is 127/8 range for IPv4 and 0:0:0:0:0:FFFF:7F00/104 for
   IPv6 then UDP destination port is 3784.

6.1.  Demux of BFD Packet:

   Demux of IP BFD packet has been defined in Section 3 of [RFC5881].
   BFD demultiplexing for VXLAN is going to be different as destination
   IP is same for all sessions and underlay is layer 3 and may have
   ECMP.  Source address and VNI should identify a BFD session on VTEP,
   initially when BFD packets are sent with with your discriminator set
   to 0 BFD packets MUST be demultiplexed with source address and VNI as
   the key.  If BFD packet is received with non-zero your discriminator
   then BFD session should be demultiplexed only with your discriminator
   as the key.

7.  Echo BFD:

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

8.  S-BFD:

   S-BFD can also be used for connectivity check as defined in
   [I-D.ietf-bfd-seamless-base]





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8.1.  Transmission of S-BFD:

   VTEP MUST encapsulate S-BFD packet as defined in Section 5.  For
   S-BFD however your Discriminator will be set to VNI from the VXLAN
   header.

8.2.  Reception of S-BFD:

   VTEP MUST decapsulate S-BFD packet as defined in above section
   "reception of BFD packet".  Reflector MUST validate if your
   Discriminator belongs any one of the VNI on that VTEP.

9.  IANA Considerations

   This document has no actions for IANA.

10.  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.

11.  Acknowledgements

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

12.  Normative References

   [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-04 (work in
              progress), January 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.



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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, August 2014.

Authors' Addresses

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

   Email: santoshpk@juniper.net


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

   Email: sparagiri@juniper.net


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

   Email: sbasil@juniper.net


















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