[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04 05 06

Internet Engineering Task Force                       S. Pallagatti, Ed.
Internet-Draft                                   Independent Contributor
Intended status: Standards Track                             S. Paragiri
Expires: April 16, 2018                                 Juniper Networks
                                                             V. Govindan
                                                            M. Mudigonda
                                                                   Cisco
                                                               G. Mirsky
                                                               ZTE Corp.
                                                        October 13, 2017


                             BFD for VXLAN
                     draft-spallagatti-bfd-vxlan-06

Abstract

   This document describes use of Bidirectional Forwarding Detection
   (BFD) protocol in Virtual eXtensible Local Area Network (VXLAN)
   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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://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 April 16, 2018.

Copyright Notice

   Copyright (c) 2017 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



Pallagatti, et al.       Expires April 16, 2018                 [Page 1]


Internet-Draft                BFD for VXLAN                 October 2017


   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.  Conventions used in this document . . . . . . . . . . . . . .   3
     2.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   3.  Use cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Deployment  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  BFD Packet Transmission over VXLAN Tunnel . . . . . . . . . .   5
     5.1.  BFD Packet Encapsulation in VXLAN . . . . . . . . . . . .   6
   6.  Reception of BFD packet from VXLAN Tunnel . . . . . . . . . .   7
     6.1.  Demultiplexing of the BFD packet  . . . . . . . . . . . .   8
   7.  Use of reserved VNI . . . . . . . . . . . . . . . . . . . . .   8
   8.  Echo BFD  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   10. Security Considerations . . . . . . . . . . . . . . . . . . .   8
   11. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   13. Normative References  . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   "Virtual eXtensible Local Area Network (VXLAN)" has been described in
   [RFC7348].  VXLAN provides an encapsulation scheme that allows
   virtual machines (VMs) to communicate in a 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 VM can communicate with another VM only if they are on the same
   VXLAN.  VMs are unaware of VXLAN tunnels as VXLAN tunnel is
   terminated on VXLAN Tunnel End Point (VTEP) (hypervisor/TOR).  VTEPs
   (hypervisor/TOR) are responsible for encapsulating and decapsulating
   frames exchanged among VMs.

   Since underlay is a L3 network, ability to monitor path continuity,
   i.e. perform proactive continuity check (CC) for these tunnels is
   important.  Asynchronous mode of BFD, as defined in [RFC5880], can be




Pallagatti, et al.       Expires April 16, 2018                 [Page 2]


Internet-Draft                BFD for VXLAN                 October 2017


   used to monitor a VXLAN tunnel.  Use of [I-D.ietf-bfd-multipoint] is
   for future study.

   Also BFD in VXLAN can be used to monitor special service nodes that
   are designated to properly handle Layer 2 broadcast, unknown unicast,
   and multicast traffic.  Such nodes, often referred "replicators", are
   usually virtual VTEPs can be monitored by physical VTEPs in order to
   minimize BUM traffic directed to unavialable replicator.

   This document describes use of Bidirectional Forwarding Detection
   (BFD) protocol VXLAN to enable continuity monitoring between Network
   Virtualization Edges (NVEs) and/or availability of a replicator
   service node using BFD.

2.  Conventions used in this document

2.1.  Terminology

   BFD - Bidirectional Forwarding Detection

   CC - Continuity Check

   NVE - Network Virtualization Edge

   TOR - Top of Rack

   VM - Virtual Machine

   VTEP - VXLAN Tunnel End Point

   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.  Use cases

   Main use case of BFD for VXLAN is for continuity check of a tunnel.
   By exchanging BFD control packets between VTEPs an operator exercises
   the VXLAN path in both in underlay and overlay thus ensuring the
   VXLAN path availability and VTEPs reachability.  BFD failure
   detection can be used for maintenance.  There are other use cases
   such as



Pallagatti, et al.       Expires April 16, 2018                 [Page 3]


Internet-Draft                BFD for VXLAN                 October 2017


      Layer 2 VMs:

         Most deployments will have VMs 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
         NVEs, e.g.  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 NVE and VTEP are used
         interchangeably.

      Fault localization:

         It is also possible that VMs are L3 aware and can possibly host
         a BFD session.  In these cases BFD sessions can be established
         among VMs 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
         host VM.  BFD session between TOR/hypervisor and service node
         can be used to monitor service node reachability.

4.  Deployment

   Figure 1 illustrates the scenario with two servers, each of them
   hosting two VMs.  These servers host VTEPs that terminate two VXLAN
   tunnels with VNI number 100 and 200.  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
   packets leading to false negative.  This method is applicable whether
   VTEP is a virtual or physical device.














Pallagatti, et al.       Expires April 16, 2018                 [Page 4]


Internet-Draft                BFD for VXLAN                 October 2017


      +------------+-------------+
      |        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: Reference VXLAN domain

5.  BFD Packet Transmission over VXLAN Tunnel

   BFD packet MUST be encapsulated and sent to a remote VTEP as
   explained in Section 5.1.  Implementations SHOULD ensure that the BFD
   packets follow the same lookup path of VXLAN packets within the
   sender system.








Pallagatti, et al.       Expires April 16, 2018                 [Page 5]


Internet-Draft                BFD for VXLAN                 October 2017


5.1.  BFD Packet Encapsulation in VXLAN

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

     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                       ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    ~                           VXLAN Header                        ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    ~                    Inner Ethernet Header                      ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    ~                        Inner IPvX Header                      ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    ~                         Inner UDP Header                      ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                                                               |
    ~                       BFD Control Message                     ~
    |                                                               |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                            FCS                                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Figure 2: VXLAN Encapsulaion of BFD Control Message






Pallagatti, et al.       Expires April 16, 2018                 [Page 6]


Internet-Draft                BFD for VXLAN                 October 2017


   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 dedicated MAC (TBA) Section 9
         or the MAC address of the destination VTEP.  The details of how
         the MAC address of the destination VTEP 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.

      The fields of the UDP header and the BFD control packet are
      encoded as specified in [RFC5881] for p2p VXLAN tunnels.

6.  Reception of BFD packet from VXLAN Tunnel

   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 dedicated MAC or the MAC address of the VTEP the
   packet MUST be processed further.

   The UDP destination port and the TTL of the inner Ethernet frame MUST
   be validated to determine if the received packet can be processed by
   BFD.  BFD packet with inner MAC set to VTEP or dedicated MAC address
   MUST NOT be forwarded to VMs.

   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.






Pallagatti, et al.       Expires April 16, 2018                 [Page 7]


Internet-Draft                BFD for VXLAN                 October 2017


6.1.  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 equal to 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
   MUST be demultiplexed only with Your Discriminator as the key.

7.  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.

8.  Echo BFD

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

9.  IANA Considerations

   IANA is requested to assign a dedicated MAC address to be used as the
   Destination MAC address of the inner Ethernet which carries BFD
   control packet in IP/UDP encapsulation.

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 packets 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.  Contributors








Pallagatti, et al.       Expires April 16, 2018                 [Page 8]


Internet-Draft                BFD for VXLAN                 October 2017


   Reshad Rahman
   rrahman@cisco.com
   Cisco


12.  Acknowledgments

   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.

13.  Normative References

   [I-D.ietf-bfd-multipoint]
              Katz, D., Ward, D., and J. Networks, "BFD for Multipoint
              Networks", draft-ietf-bfd-multipoint-10 (work in
              progress), April 2017.

   [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>.

   [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>.

   [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>.







Pallagatti, et al.       Expires April 16, 2018                 [Page 9]


Internet-Draft                BFD for VXLAN                 October 2017


Authors' Addresses

   Santosh Pallagatti (editor)
   Independent Contributor

   Email: santosh.pallagatti@gmail.com


   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
   ZTE Corp.

   Email: gregimirsky@gmail.com


















Pallagatti, et al.       Expires April 16, 2018                [Page 10]


Html markup produced by rfcmarkup 1.124, available from https://tools.ietf.org/tools/rfcmarkup/