Internet DRAFT - draft-ietf-bfd-vxlan

draft-ietf-bfd-vxlan







BFD                                                   S. Pallagatti, Ed.
Internet-Draft                                                   Rtbrick
Intended status: Standards Track                             S. Paragiri
Expires: November 18, 2019                        Individual Contributor
                                                             V. Govindan
                                                            M. Mudigonda
                                                                   Cisco
                                                               G. Mirsky
                                                               ZTE Corp.
                                                            May 17, 2019


                             BFD for VXLAN
                        draft-ietf-bfd-vxlan-07

Abstract

   This document describes the use of the Bidirectional Forwarding
   Detection (BFD) protocol in point-to-point Virtual eXtensible Local
   Area Network (VXLAN) tunnels forming 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
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on November 18, 2019.

Copyright Notice

   Copyright (c) 2019 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



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   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.  Deployment  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  BFD Packet Transmission over VXLAN Tunnel . . . . . . . . . .   5
     4.1.  BFD Packet Encapsulation in VXLAN . . . . . . . . . . . .   6
   5.  Reception of BFD Packet from VXLAN Tunnel . . . . . . . . . .   7
     5.1.  Demultiplexing of the BFD Packet  . . . . . . . . . . . .   7
   6.  Use of the Specific VNI . . . . . . . . . . . . . . . . . . .   8
   7.  Echo BFD  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   9
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     12.2.  Informational References . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   "Virtual eXtensible Local Area Network" (VXLAN) [RFC7348] 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.

   One use of VXLAN is in data centers interconnecting virtual machines
   (VMs) of a tenant.  VXLAN addresses requirements of the Layer 2 and
   Layer 3 data center network infrastructure in the presence of VMs in
   a multi-tenant environment by providing a Layer 2 overlay scheme on a
   Layer 3 network [RFC7348].  Another use is as an encapsulation for
   Ethernet VPN [RFC8365].

   This document is written assuming the use of VXLAN for virtualized
   hosts and refers to VMs and VXLAN Tunnel End Points (VTEPs) in
   hypervisors.  However, the concepts are equally applicable to non-
   virtualized hosts attached to VTEPs in switches.

   In the absence of a router in the overlay, a VM can communicate with
   another VM only if they are on the same VXLAN segment.  VMs are



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   unaware of VXLAN tunnels as a VXLAN tunnel is terminated on a VTEP.
   VTEPs are responsible for encapsulating and decapsulating frames
   exchanged among VMs.

   Ability to monitor path continuity, i.e., perform proactive
   continuity check (CC) for point-to-point (p2p) VXLAN tunnels, is
   important.  The asynchronous mode of BFD, as defined in [RFC5880],
   can be used to monitor a p2p VXLAN tunnel.

   In the case where a Multicast Service Node (MSN) (as described in
   Section 3.3 of [RFC8293]) resides behind an NVE, the mechanisms
   described in this document apply and can, therefore, be used to test
   the connectivity from the source NVE to the MSN.

   This document describes the use of Bidirectional Forwarding Detection
   (BFD) protocol to enable monitoring continuity of the path between
   VXLAN VTEPs, performing as Network Virtualization Endpoints, and/or
   availability of a replicator multicast service node.

2.  Conventions used in this document

2.1.  Terminology

   BFD Bidirectional Forwarding Detection

   CC Continuity Check

   p2p Point-to-point

   MSN Multicast Service Node

   VFI Virtual Forwarding Instance

   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.





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3.  Deployment

   Figure 1 illustrates the scenario with two servers, each of them
   hosting two VMs.  The servers host VTEPs that terminate two VXLAN
   tunnels with VNI number 100 and 200 respectively.  Separate BFD
   sessions can be established between the VTEPs (IP1 and IP2) for
   monitoring each of the VXLAN tunnels (VNI 100 and 200).  An
   implementation that supports this specification MUST be able to
   control the number of BFD sessions that can be created between the
   same pair of VTEPs.  BFD packets intended for a Hypervisor VTEP MUST
   NOT be forwarded to a VM as a VM may drop BFD packets leading to a
   false negative.  This method is applicable whether the VTEP is a
   virtual or physical device.






































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



                     Figure 1: Reference VXLAN Domain

4.  BFD Packet Transmission over VXLAN Tunnel

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








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4.1.  BFD Packet Encapsulation in VXLAN

   BFD packets are encapsulated in VXLAN as described below.  The VXLAN
   packet format is defined in Section 5 of [RFC7348].  The Outer IP/UDP
   and VXLAN headers MUST be encoded by the sender as defined in
   [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 Encapsulation of BFD Control Message





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   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 the dedicated MAC TBA (Section 8)
         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: MUST be set to 1 to ensure that the BFD packet is not
         routed within the L3 underlay network.

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

5.  Reception of BFD Packet from VXLAN Tunnel

   Once a packet is received, VTEP MUST validate the packet.  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 IP packet 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.

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 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, the destination IP, and
   the source UDP port number 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



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   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.

6.  Use of the Specific VNI

   In most cases, a single BFD session is sufficient for the given VTEP
   to monitor the reachability of a remote VTEP, regardless of the
   number of VNIs in common.  When the single BFD session is used to
   monitor the reachability of the remote VTEP, an implementation SHOULD
   choose any of the VNIs but MAY choose VNI = 0.

7.  Echo BFD

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

8.  IANA Considerations

   IANA has assigned TBA as a dedicated MAC address from the IANA 48-bit
   unicast MAC address registry to be used as the Destination MAC
   address of the inner Ethernet of VXLAN when carrying BFD control
   packets.

9.  Security Considerations

   The document requires setting the inner IP TTL to 1, which could be
   used as a DDoS attack vector.  Thus the implementation MUST have
   throttling in place to control the rate of BFD control packets sent
   to the control plane.  Throttling MAY be relaxed for BFD packets
   based on port number.

   The implementation SHOULD have a reasonable upper bound on the number
   of BFD sessions that can be created between the same pair of VTEPs.

   Other than inner IP TTL set to 1 and limit the number of BFD sessions
   between the same pair of VTEPs, 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






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11.  Acknowledgments

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

   Authors would also like to thank Nobo Akiya, Marc Binderberger,
   Shahram Davari, Donald E.  Eastlake 3rd, and Anoop Ghanwani for the
   extensive reviews and the most detailed and helpful comments.

12.  References

12.1.  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>.

   [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>.

12.2.  Informational References

   [RFC8293]  Ghanwani, A., Dunbar, L., McBride, M., Bannai, V., and R.
              Krishnan, "A Framework for Multicast in Network
              Virtualization over Layer 3", RFC 8293,
              DOI 10.17487/RFC8293, January 2018,
              <https://www.rfc-editor.org/info/rfc8293>.






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   [RFC8365]  Sajassi, A., Ed., Drake, J., Ed., Bitar, N., Shekhar, R.,
              Uttaro, J., and W. Henderickx, "A Network Virtualization
              Overlay Solution Using Ethernet VPN (EVPN)", RFC 8365,
              DOI 10.17487/RFC8365, March 2018,
              <https://www.rfc-editor.org/info/rfc8365>.

Authors' Addresses

   Santosh Pallagatti (editor)
   Rtbrick

   Email: santosh.pallagatti@gmail.com


   Sudarsan Paragiri
   Individual Contributor

   Email: sudarsan.225@gmail.com


   Vengada Prasad Govindan
   Cisco

   Email: venggovi@cisco.com


   Mallik Mudigonda
   Cisco

   Email: mmudigon@cisco.com


   Greg Mirsky
   ZTE Corp.

   Email: gregimirsky@gmail.com















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