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Versions: 00 01 02 03 04 05 06 draft-ietf-bfd-vxlan

Internet Engineering Task Force                       S. Pallagatti, Ed.
Internet-Draft                                   Independent Contributor
Intended status: Standards Track                                 B. Saji
Expires: October 17, 2016                                    S. Paragiri
                                                        Juniper Networks
                                                        V. Govindan, Ed.
                                                            M. Mudigonda
                                                                   Cisco
                                                               G. Mirsky
                                                                Ericsson
                                                          April 15, 2016


                             BFD for VXLAN
                     draft-spallagatti-bfd-vxlan-03

Abstract

   This document describes use of Bidirectional Forwarding Detection
   (BFD) protocol for VXLAN .

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 October 17, 2016.








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Copyright Notice

   Copyright (c) 2016 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
   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  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  BFD Packet Transmission . . . . . . . . . . . . . . . . . . .   5
     4.1.  BFD Packet Encapsulation  . . . . . . . . . . . . . . . .   5
   5.  Reception of BFD packet . . . . . . . . . . . . . . . . . . .   6
     5.1.  Demultiplexing of the BFD packet  . . . . . . . . . . . .   6
   6.  Use of reserved VNI . . . . . . . . . . . . . . . . . . . . .   6
   7.  Echo BFD  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   7
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   12. Normative References  . . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

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 center network.

   VXLAN is typically deployed in data centers interconnecting
   virtualized hosts, which may be spread across multiple racks.  The
   individual racks may be part 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 virtual machine (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 is terminated on VXLAN Tunnel End Point(VTEP)



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   (hypervisor/TOR).  VTEPs (hypervisor/TOR) are responsible for
   encapsulating and decapsulating frames exchanged among VM's.

   Since underlay is a L3 network, continuity check for these tunnels
   becomes important.  BFD as defined in [RFC5880] can be used to
   monitor the VXLAN tunnels.  Use of [I-D.ietf-bfd-multipoint] is for
   future study.

   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 continuity check.  BFD
   packets between VTEPs will exercise the VXLAN path in underlay/
   overlay ensuring the VXLAN path reachability.  BFD failure detection
   can be used for maintenance.  There are other use cases such as

      Layer 2 VM's:

         Most deployments will have VM's with only L2 capabilities that
         may not support L3.  BFD being a L3 protocol can be used as
         tunnel CC mechanism, where BFD will start and terminate at the
         Network Virtualization (NV) Edge (VTEPs).

         It is possible to aggregate the CC sessions 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 among VM's for CC.  In addition BFD sessions can be
         established among VTEPs for tunnel CC.  Having a hierarchical
         OAM model helps localize faults though requires additional
         consideration.

      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




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         host VM's.  BFD session between TOR/hypervisor and service node
         can be used to monitor service node reachability.

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 the 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 packets intended to
   Hypervisor VTEP should be forwarded to a VM as VM may drop BFD




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   packets leading to false negative.  This method is applicable whether
   VTEP is a software or a physical device.

4.  BFD Packet Transmission

   BFD packet MUST be encapsulated and sent to remote VTEP as explained
   in Section 4.1.  Implementations SHOULD ensure that the BFD packets
   follow the same lookup path of VXLAN packets within the sender
   system.

4.1.  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 Generic Protocol Extension (GPE) header
   capabilities 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 are 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 are 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.

         [Ed.Note]:Use of inner source and destination IP addresses
         needs more discussion by the WG.



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      The fields of the UDP header and the BFD control packet are
      encoded as specified in RFC 5881 for p2p VXLAN tunnels.

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.

   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.

   To ensure BFD detects the proper configuration of VXLAN Network
   Identifier(VNI) in a remote VTEP, a lookup SHOULD be performed with
   the MAC-DA and VNI as key in the Virtual Forwarding Instance(VFI)
   table of the originating/ terminating VTEP in order to exercise the
   VFI associated with the VNI.

5.1.  Demultiplexing of the BFD packet

   Demultiplexing 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 MUST be identified using the inner
   headers, i.e. the source IP and the destination IP present in the IP
   header carried by the payload of the VXLAN encapsulated packet.  The
   VNI of the packet SHOULD be used to derive interface related
   information for demultiplexing 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.  Use of reserved VNI

   BFD session MAY be established for the reserved VNI 0.  One way to
   aggregate BFD sessions between VTEP's is to establish a BFD session
   with VNI 0.  A VTEP MAY also use VNI 0 to establish a BFD session
   with a service node.

7.  Echo BFD

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





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8.  IANA Considerations

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

9.  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.

10.  Contributors

   Reshad Rahman
   rrahman@cisco.com
   Cisco

11.  Acknowledgements

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

   Authors would also like to thank Nobo Akiya, Marc Binderberger and
   Shahram Davari for the extensive review.

12.  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-multipoint]
              Katz, D., Ward, D., and J. Networks, "BFD for Multipoint
              Networks", draft-ietf-bfd-multipoint-07 (work in
              progress), August 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.



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

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <http://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,
              <http://www.rfc-editor.org/info/rfc5881>.

   [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,
              <http://www.rfc-editor.org/info/rfc7348>.

Authors' Addresses

   Santosh Pallagatti (editor)
   Independent Contributor

   Email: santoshpk@juniper.net


   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






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   Vengada Prasad Govindan (editor)
   Cisco

   Email: venggovi@cisco.com


   Mallik Mudigonda
   Cisco

   Email: mmudigon@cisco.com


   Greg Mirsky
   Ericsson

   Email: gregory.mirsky@ericsson.com



































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