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Versions: (draft-quinn-vxlan-gpe) 00 01 02 03 04 05

Network Working Group                                      F. Maino, Ed.
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                         L. Kreeger, Ed.
Expires: October 29, 2017
                                                           U. Elzur, Ed.
                                                                   Intel
                                                          April 27, 2017


                  Generic Protocol Extension for VXLAN
                      draft-ietf-nvo3-vxlan-gpe-04

Abstract

   This draft describes extending Virtual eXtensible Local Area Network
   (VXLAN), via changes to the VXLAN header, with three new
   capabilities: support for multi-protocol encapsulation, operations,
   administration and management (OAM) signaling and explicit
   versioning.

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 [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 29, 2017.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.




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   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.  VXLAN Without Protocol Extension  . . . . . . . . . . . . . .   3
   3.  Generic Protocol Extension for VXLAN (VXLAN GPE)  . . . . . .   4
     3.1.  VXLAN GPE Header  . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Multi Protocol Support  . . . . . . . . . . . . . . . . .   5
     3.3.  Replicated BUM Traffic  . . . . . . . . . . . . . . . . .   6
     3.4.  OAM Support . . . . . . . . . . . . . . . . . . . . . . .   6
     3.5.  Version Bits  . . . . . . . . . . . . . . . . . . . . . .   6
   4.  Outer Encapsulations  . . . . . . . . . . . . . . . . . . . .   7
     4.1.  Inner VLAN Tag Handling . . . . . . . . . . . . . . . . .  10
     4.2.  Fragmentation Considerations  . . . . . . . . . . . . . .  11
   5.  Backward Compatibility  . . . . . . . . . . . . . . . . . . .  11
     5.1.  VXLAN VTEP to VXLAN GPE VTEP  . . . . . . . . . . . . . .  11
     5.2.  VXLAN GPE VTEP to VXLAN VTEP  . . . . . . . . . . . . . .  11
     5.3.  VXLAN GPE UDP Ports . . . . . . . . . . . . . . . . . . .  11
     5.4.  VXLAN GPE and Encapsulated IP Header Fields . . . . . . .  12
   6.  VXLAN GPE Examples  . . . . . . . . . . . . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  13
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  14
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     10.1.  UDP Port . . . . . . . . . . . . . . . . . . . . . . . .  14
     10.2.  VXLAN GPE Next Protocol  . . . . . . . . . . . . . . . .  14
     10.3.  VXLAN GPE Flag and Reserved Bits . . . . . . . . . . . .  14
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     11.2.  Informative References . . . . . . . . . . . . . . . . .  16
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Virtual eXtensible Local Area Network VXLAN [RFC7348] defines an
   encapsulation format that encapsulates Ethernet frames in an outer
   UDP/IP transport.  As data centers evolve, the need to carry other
   protocols encapsulated in an IP packet is required, as well as the
   need to provide increased visibility and diagnostic capabilities



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   within the overlay.  The VXLAN header does not specify the protocol
   being encapsulated and therefore is currently limited to
   encapsulating only Ethernet frame payload, nor does it provide the
   ability to define OAM protocols.  In addition, [RFC6335] requires
   that new transports not use transport layer port numbers to identify
   tunnel payload, rather it encourages encapsulations to use their own
   identifiers for this purpose.  VXLAN GPE is intended to extend the
   existing VXLAN protocol to provide protocol typing, OAM, and
   versioning capabilities.

   The Version and OAM bits are introduced in Section 3, and the choice
   of location for these fields is driven by minimizing the impact on
   existing deployed hardware.

   In order to facilitate deployments of VXLAN GPE with hardware
   currently deployed to support VXLAN, changes from legacy VXLAN have
   been kept to a minimum.  Section 5 provides a detailed discussion
   about how VXLAN GPE addresses the requirement for backward
   compatibility with VXLAN.

2.  VXLAN Without Protocol Extension

   VXLAN provides a method of creating multi-tenant overlay networks by
   encapsulating packets in IP/UDP along with a header containing a
   network identifier which is used to isolate tenant traffic in each
   overlay network from each other.  This allows the overlay networks to
   run over an existing IP network.

   Through this encapsulation, VXLAN creates stateless tunnels between
   VXLAN Tunnel End Points (VTEPs) which are responsible for adding/
   removing the IP/UDP/VXLAN headers and providing tenant traffic
   isolation based on the VXLAN Network Identifier (VNI).  Tenant
   systems are unaware that their networking service is being provided
   by an overlay.

   When encapsulating packets, a VTEP must know the IP address of the
   proper remote VTEP at the far end of the tunnel that can deliver the
   inner packet to the Tenant System corresponding to the inner
   destination address.  In the case of tenant multicast or broadcast,
   the outer IP address may be an IP multicast group address, or the
   VTEP may replicate the packet and send it to all known VTEPs.  If
   multicast is used in the underlay network to send encapsulated
   packets to remote VTEPs, Any Source Multicast is used and each VTEP
   serving a particular VNI must perform a (*, G) join to the same group
   IP address.






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   Inner to outer address mapping can be determined in two ways.  One is
   source based learning in the data plane, and the other is
   distribution via a control plane.

   Source based learning requires a receiving VTEP to create an inner to
   outer address mapping by gleaning the information from the received
   packets by correlating the inner source address to the outer source
   IP address.  When a mapping does not exist, a VTEP forwards the
   packets to all remote VTEPs participating in the VNI by using IP
   multicast in the IP underlay network.  Each VTEP must be configured
   with the IP multicast address to use for each VNI.  How this occurs
   is out of scope.

   The control plane used to distribute inner to outer mappings is also
   out of scope.  It could use a centralized authority or be
   distributed, or use a hybrid.

   The VXLAN Network Identifier (VNI) provides scoping for the addresses
   in the header of the encapsulated PDU.  If the encapsulated packet is
   an Ethernet frame, this means the Ethernet MAC addresses are only
   unique within a given VNI and may overlap with MAC addresses within a
   different VNI.  If the encapsulated packet is an IP packet, this
   means the IP addresses are only unique within that VNI.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |R|R|R|R|I|R|R|R|            Reserved                           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                VXLAN Network Identifier (VNI) |   Reserved    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                          Figure 1: VXLAN Header

3.  Generic Protocol Extension for VXLAN (VXLAN GPE)

3.1.  VXLAN GPE Header

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |R|R|Ver|I|P|B|O|       Reserved                |Next Protocol  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                VXLAN Network Identifier (VNI) |   Reserved    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 2: VXLAN GPE Header




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   Flags (8 bits):  The first 8 bits of the header are the flag field.
      The bits designated "R" above are reserved flags.  These MUST be
      set to zero on transmission and ignored on receipt.

   Version (Ver):  Indicates VXLAN GPE protocol version.  The initial
      version is 0.  If a receiver does not support the version
      indicated it MUST drop the packet.

   Instance Bit (I bit):  The I bit MUST be set to indicate a valid VNI.

   Next Protocol Bit (P bit):  The P bit is set to indicate that the
      Next Protocol field is present.

   BUM Traffic Bit (B bit):  The B bit is set to indicate that this is
      ingress-replicated BUM Traffic (ie, Broadcast, Unknown unicast, or
      Multicast).

   OAM Flag Bit (O bit):  The O bit is set to indicate that the packet
      is an OAM packet.

   Next Protocol:  This 8 bit field indicates the protocol header
      immediately following the VXLAN GPE header.

   VNI:  This 24 bit field identifies the VXLAN overlay network the
      inner packet belongs to.  Inner packets belonging to different
      VNIs cannot communicate with each other (unless explicitly allowed
      by policy).

   Reserved:  Reserved fields MUST be set to zero on transmission and
      ignored on receipt.

3.2.  Multi Protocol Support

   This draft defines the following two changes to the VXLAN header in
   order to support multi-protocol encapsulation:

   P Bit:  Flag bit 5 is defined as the Next Protocol bit.  The P bit
      MUST be set to 1 to indicate the presence of the 8 bit next
      protocol field.

      When UDP dest port=4790, P = 0 the "Next Protocol" field must be
      set to zero and the payload MUST be ETHERNET(L2) as defined by
      [RFC7348].

      Flag bit 5 was chosen as the P bit because this flag bit is
      currently reserved in VXLAN.





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   Next Protocol Field:  The lower 8 bits of the first word are used to
      carry a next protocol.  This next protocol field contains the
      protocol of the encapsulated payload packet.  A new protocol
      registry will be requested from IANA, see section 9.2.

      This draft defines the following Next Protocol values:



      0x1 :  IPv4

      0x2 :  IPv6

      0x3 :  Ethernet

      0x4 :  Network Service Header [I-D.ietf-sfc-nsh]

      0x5 :  Multiprotocol Label Switching [RFC3031].  Please see
         [I-D.ietf-idr-tunnel-encaps] for more details.

3.3.  Replicated BUM Traffic

   Flag bit 6 is defined as the B bit.  When the B bit is set to 1, the
   packet is marked as an an ingress-replicated BUM Traffic (i.e.
   Broadcast, Unknown unicast, or Multicast) to help egress VTEP to
   differentiate between known and unknown unicast.  The details of
   using the B bit are out of scope for this document, but please see
   [I-D.ietf-bess-evpn-overlay] for an example in the EVPN context.  As
   with the P-bit, bit 6 is currently a reserved flag in VXLAN.

3.4.  OAM Support

   Flag bit 7 is defined as the O bit.  When the O bit is set to 1, the
   packet is an OAM packet and OAM processing MUST occur.  Other header
   fields including Next Protocol MUST adhere to the definitions in
   Section 3.  The OAM protocol details are out of scope for this
   document.  As with the P-bit, bit 7 is currently a reserved flag in
   VXLAN.

3.5.  Version Bits

   VXLAN GPE bits 2 and 3 are defined as version bits.  These bits are
   reserved in VXLAN.  The version field is used to ensure backward
   compatibility going forward with future VXLAN GPE updates.

   The initial version for VXLAN GPE is 0.





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4.  Outer Encapsulations

   In addition to the VXLAN GPE header, the packet is further
   encapsulated in UDP and IP.  Data centers based on Ethernet, will
   then send this IP packet over Ethernet.

   Outer UDP Header:

   Destination UDP Port: IANA has assigned the value 4790 for the VXLAN
   GPE UDP port.  This well-known destination port is used when sending
   VXLAN GPE encapsulated packets.

   Source UDP Port: The source UDP port is used as entropy for devices
   forwarding encapsulated packets across the underlay (ECMP for IP
   routers, or load splitting for link aggregation by bridges).  Tenant
   traffic flows should all use the same source UDP port to lower the
   chances of packet reordering by the underlay for a given flow.  It is
   recommended for VTEPs to generate this port number using a hash of
   the inner packet headers.  Implementations MAY use the entire 16 bit
   source UDP port for entropy.

   UDP Checksum: Source VTEPs MAY either calculate a valid checksum, or
   if this is not possible, set the checksum to zero.  When calculating
   a checksum, it MUST be calculated across the entire packet (outer IP
   header, UDP header, VXLAN GPE header and payload packet).  All
   receiving VTEPs must accept a checksum value of zero.  If the
   receiving VTEP is capable of validating the checksum, it MAY validate
   a non-zero checksum and MUST discard the packet if the checksum is
   determined to be invalid.

   Outer IP Header:

   This is the header used by the underlay network to deliver packets
   between VTEPs.  The destination IP address can be a unicast or a
   multicast IP address.  The source IP address must be the source VTEP
   IP address which can be used to return tenant packets to the tenant
   system source address within the inner packet header.

   When the outer IP header is IPv4, VTEPs MUST set the DF bit.

   Outer Ethernet Header:

   Most data centers networks are built on Ethernet.  Assuming the outer
   IP packet is being sent across Ethernet, there will be an Ethernet
   header used to deliver the IP packet to the next hop, which could be
   the destination VTEP or be a router used to forward the IP packet
   towards the destination VTEP.  If VLANs are in use within the data
   center, then this Ethernet header would also contain a VLAN tag.



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   The following figures show the entire stack of protocol headers that
   would be seen on an Ethernet link carrying encapsulated packets from
   a VTEP across the underlay network for both IPv4 and IPv6 based
   underlay networks.

        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 Destination MAC Address                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Outer Destination MAC Address | Outer Source MAC Address      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Outer Source MAC Address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Opt Ethertype = C-Tag 802.1Q  |     Outer VLAN Tag            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Ethertype = 0x0800            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Outer IPv4 Header:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Version|  IHL  |Type of Service|          Total Length         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Identification        |Flags|      Fragment Offset    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Time to Live |Protocl=17(UDP)|   Header Checksum             |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                       Outer Source IPv4 Address               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Outer Destination IPv4 Address              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Outer UDP Header:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Source Port         |       Dest Port = 4790        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           UDP Length          |        UDP Checksum           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       VXLAN GPE Header:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |R|R|Ver|I|P|R|O|       Reserved                |Next Protocol  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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       |                VXLAN Network Identifier (VNI) |   Reserved    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Payload:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Depends on VXLAN GPE Next Protocol field above.          |
       |    Note that if the payload is Ethernet, then the original    |
       |    Ethernet Frame's FCS is not included.                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Frame Check Sequence:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   New FCS (Frame Check Sequence) for Outer Ethernet Frame     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 3: Outer Headers for VXLAN GPE over IPv4

        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 Destination MAC Address                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Outer Destination MAC Address | Outer Source MAC Address      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                Outer Source MAC Address                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Opt Ethertype = C-Tag 802.1Q  |     Outer VLAN Tag            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Ethertype = 0x86DD            |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Outer IPv6 Header:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |Version| Traffic Class |           Flow Label                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Payload Length        | NxtHdr=17(UDP)|   Hop Limit   |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                     Outer Source IPv6 Address                 +
       |                                                               |
       +                                                               +
       |                                                               |



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       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                  Outer Destination IPv6 Address               +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Outer UDP Header:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           Source Port         |       Dest Port = 4790        |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |           UDP Length          |        UDP Checksum           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       VXLAN GPE Header:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |R|R|Ver|I|P|R|O|       Reserved                |Next Protocol  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                VXLAN Network Identifier (VNI) |   Reserved    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Payload:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Depends on VXLAN GPE Next Protocol field above.          |
       |    Note that if the payload is Ethernet, then the original    |
       |    Ethernet Frame's FCS is not included.                      |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Frame Check Sequence:
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   New FCS (Frame Check Sequence) for Outer Ethernet Frame     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 4: Outer Headers for VXLAN GPE over IPv6

4.1.  Inner VLAN Tag Handling

   If the inner packet (as indicated by the VXLAN GPE Next Protocol
   field) is an Ethernet frame, it is recommended that it does not
   contain a VLAN tag.  In the most common scenarios, the tenant VLAN
   tag is translated into a VXLAN Network Identifier.  In these
   scenarios, VTEPs should never send an inner Ethernet frame with a
   VLAN tag, and a VTEP performing decapsulation should discard any
   inner frames received with a VLAN tag.  However, if the VTEPs are
   specifically configured to support it for a specific VXLAN Network



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   Identifier, a VTEP may support transparent transport of the inner
   VLAN tag between all tenant systems on that VNI.  The VTEP never
   looks at the value of the inner VLAN tag, but simply passes it across
   the underlay.

4.2.  Fragmentation Considerations

   VTEPs MUST never fragment an encapsulated VXLAN GPE packet, and when
   the outer IP header is IPv4, VTEPs MUST set the DF bit in the outer
   IPv4 header.  It is recommended that the underlay network be
   configured to carry an MTU at least large enough to accommodate the
   added encapsulation headers.  It is recommended that VTEPs perform
   Path MTU discovery [RFC1191] [RFC1981] to determine if the underlay
   network can carry the encapsulated payload packet.

5.  Backward Compatibility

5.1.  VXLAN VTEP to VXLAN GPE VTEP

   A VXLAN VTEP conforms to VXLAN frame format and uses UDP destination
   port 4789 when sending traffic to VXLAN GPE VTEP.  As per VXLAN,
   reserved bits 5 and 7, VXLAN GPE P and O-bits respectively must be
   set to zero.  The remaining reserved bits must be zero, including the
   VXLAN GPE version field, bits 2 and 3.  The encapsulated payload MUST
   be Ethernet.

5.2.  VXLAN GPE VTEP to VXLAN VTEP

   A VXLAN GPE VTEP MUST NOT encapsulate non-Ethernet frames to a VXLAN
   VTEP.  When encapsulating Ethernet frames to a VXLAN VTEP, the VXLAN
   GPE VTEP MUST conform to VXLAN frame format and hence will set the P
   bit to 0, the Next Protocol to 0 and use UDP destination port 4789.
   A VXLAN GPE VTEP MUST also set O = 0 and Ver = 0 when encapsulating
   Ethernet frames to VXLAN VTEP.  The receiving VXLAN VTEP will treat
   this packet as a VXLAN packet.

   A method for determining the capabilities of a VXLAN VTEP (GPE or
   non-GPE) is out of the scope of this draft.

5.3.  VXLAN GPE UDP Ports

   VXLAN GPE uses a IANA assigned UDP destination port, 4790, when
   sending traffic to VXLAN GPE VTEPs.








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5.4.  VXLAN GPE and Encapsulated IP Header Fields

   When encapsulating and decapsulating IPv4 and IPv6 packets, certain
   fields, such as IPv4 Time to Live (TTL) from the inner IP header need
   to be considered.  VXLAN GPE IP encapsulation and decapsulation
   utilizes the techniques described in [RFC6830], section 5.3.

6.  VXLAN GPE Examples

   This section provides three examples of protocols encapsulated using
   the Generic Protocol Extension for VXLAN described in this document.

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |R|R|0|0|I|1|R|0|       Reserved                |    NP = IPv4  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                VXLAN Network Identifier (VNI) |   Reserved    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Original IPv4 Packet                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 5: IPv4 and VXLAN GPE

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |R|R|0|0|I|1|R|0|       Reserved                |  NP = IPv6    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                VXLAN Network Identifier (VNI) |   Reserved    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Original IPv6 Packet                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                       Figure 6: IPv6 and VXLAN GPE

       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |R|R|0|0|I|1|R|0|       Reserved                |NP = Ethernet  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                VXLAN Network Identifier (VNI) |   Reserved    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |               Original Ethernet Frame                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Figure 7: Ethernet and VXLAN GPE




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7.  Security Considerations

   VXLAN's security is focused on issues around L2 encapsulation into
   L3.  With VXLAN GPE, issues such as spoofing, flooding, and traffic
   redirection are dependent on the particular protocol payload
   encapsulated.

8.  Contributors

      Paul Quinn
      Cisco Systems
      paulq@cisco.com

      Rajeev Manur
      Broadcom
      rmanur@broadcom.com

      Michael Smith
      Cisco Systems
      michsmit@cisco.com

      Darrel Lewis
      Cisco Systems
      darlewis@cisco.com

      Puneet Agarwal
      Innovium, Inc
      puneet@acm.org

      Lucy Yong
      Huawei USA
      lucy.yong@huawei.com

      Xiaohu Xu
      Huawei Technologies
      xuxiaohu@huawei.com

      Pankaj Garg
      Microsoft
      pankajg@microsoft.com

      David Melman
      Marvell
      davidme@marvell.com







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9.  Acknowledgments

   A special thank you goes to Dino Farinacci for his guidance and
   detailed review.

10.  IANA Considerations

10.1.  UDP Port

   UDP 4790 port has been assigned by IANA for VXLAN GPE.

10.2.  VXLAN GPE Next Protocol

   IANA is requested to set up a registry of "Next Protocol".  These are
   8-bit values.  Next Protocol values 0, 1, 2, 3 and 4 are defined in
   this draft.  New values are assigned via Standards Action [RFC5226].

              +---------------+-------------+---------------+
              | Next Protocol | Description | Reference     |
              +---------------+-------------+---------------+
              | 0             | Reserved    | This Document |
              | 1             | IPv4        | This Document |
              | 2             | IPv6        | This Document |
              | 3             | Ethernet    | This Document |
              | 4             | NSH         | This Document |
              | 5             | MPLS        | This Document |
              | 6..253        | Unassigned  |               |
              +---------------+-------------+---------------+

10.3.  VXLAN GPE Flag and Reserved Bits

   There are ten flag bits at the beginning of the VXLAN GPE header,
   followed by 16 reserved bits and an 8-bit reserved field at the end
   of the header.  New bits are assigned via Standards Action [RFC5226].

      Bits 0-1 - Reserved

      Bits 2-3 - Version

      Bit 4 - Instance ID (I bit)

      Bit 5 - Next Protocol (P bit)

      Bit 6 - Reserved

      Bit 7 - OAM (O bit)

      Bit 8-23 - Reserved



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      Bits 24-31 in the 2nd Word -- Reserved

   Reserved bits/fields MUST be set to 0 by the sender and ignored by
   the receiver.

11.  References

11.1.  Normative References

   [RFC1191]  Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
              DOI 10.17487/RFC1191, November 1990,
              <http://www.rfc-editor.org/info/rfc1191>.

   [RFC1981]  McCann, J., Deering, S., and J. Mogul, "Path MTU Discovery
              for IP version 6", RFC 1981, DOI 10.17487/RFC1981, August
              1996, <http://www.rfc-editor.org/info/rfc1981>.

   [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>.

   [RFC3031]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
              Label Switching Architecture", RFC 3031,
              DOI 10.17487/RFC3031, January 2001,
              <http://www.rfc-editor.org/info/rfc3031>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <http://www.rfc-editor.org/info/rfc5226>.

   [RFC6335]  Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
              Cheshire, "Internet Assigned Numbers Authority (IANA)
              Procedures for the Management of the Service Name and
              Transport Protocol Port Number Registry", BCP 165,
              RFC 6335, DOI 10.17487/RFC6335, August 2011,
              <http://www.rfc-editor.org/info/rfc6335>.

   [RFC6830]  Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
              Locator/ID Separation Protocol (LISP)", RFC 6830,
              DOI 10.17487/RFC6830, January 2013,
              <http://www.rfc-editor.org/info/rfc6830>.








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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, DOI 10.17487/RFC7348, August 2014,
              <http://www.rfc-editor.org/info/rfc7348>.

11.2.  Informative References

   [I-D.ietf-bess-evpn-overlay]
              Sajassi, A., Drake, J., Bitar, N., Shekhar, R., Uttaro,
              J., and W. Henderickx, "A Network Virtualization Overlay
              Solution using EVPN", draft-ietf-bess-evpn-overlay-08
              (work in progress), March 2017.

   [I-D.ietf-idr-tunnel-encaps]
              Rosen, E., Patel, K., and G. Velde, "The BGP Tunnel
              Encapsulation Attribute", draft-ietf-idr-tunnel-encaps-04
              (work in progress), April 2017.

   [I-D.ietf-sfc-nsh]
              Quinn, P. and U. Elzur, "Network Service Header", draft-
              ietf-sfc-nsh-12 (work in progress), February 2017.

Authors' Addresses

   Fabio Maino (Editor)
   Cisco Systems

   Email: fmaino@cisco.com


   Larry Kreeger (editor)

   Email: lkreeger@gmail.com


   Uri Elzur (editor)
   Intel

   Email: uri.elzur@intel.com










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