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Versions: 00 01

INTERNET-DRAFT                                              Sami Boutros
Intended Status: Standard Track                       Jerome Catrouillet
                                                                  VMware


Expires: January 8, 2020                                    July 7, 2019


                   MAC move over Geneve encapsulation
               draft-boutros-nvo3-mac-move-over-geneve-01


Abstract

   This document specifies a mechanism to signal Media Access Control
   (MAC) addresses move over a Network Virtualization Overlays over
   Layer 3 (NVO3) virtual tunnel.  Such notification is useful in
   redundancy scenarios when a Layer 2 service that was active on a
   Network Virtualization Edge (NVE) fails over to a standby NVE. This
   notification can be used only when data plane mac learning is enabled
   over the NVO3 tunnels.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
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   The list of current Internet-Drafts can be accessed at
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   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html


Copyright and License Notice

   Copyright (c) 2019 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  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2 Abbreviations  . . . . . . . . . . . . . . . . . . . . . . .  3
   2. MAC Move Frame Format . . . . . . . . . . . . . . . . . . . . .  5
   3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1 Operation of Sender  . . . . . . . . . . . . . . . . . . . .  6
     3.2 Operation of Receiver  . . . . . . . . . . . . . . . . . . .  7
   4. Security Considerations . . . . . . . . . . . . . . . . . . . .  7
   5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  7
   6  References  . . . . . . . . . . . . . . . . . . . . . . . . . .  8
     6.1  Normative References  . . . . . . . . . . . . . . . . . . .  8
     6.2  Informative References  . . . . . . . . . . . . . . . . . .  8
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  8
























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1  Introduction

   In multi-homing scenarios a Layer 2 service can be multi-homed to
   more than one Network virtualization Edge (NVE). Only one NVE can be
   active for a given Layer 2 service, and a standby NVE can be chosen
   to take over the Layer 2 service when the active NVE goes down. The
   mechanisms to elect which NVE will be active or standby to provide
   single active redundancy for a given Layer 2 service is outside the
   scope of this document.

   When a standby NVE gets activated, Standby NVE needs to send a MAC
   Move message to all remote NVE(s) that spans this L2 service over the
   Geneve tunnels to Move all MAC learned in data plane via the old
   active NVE.

   The MAC Move message will contain the NVE Identifier(s) of the old
   Active NVE and the new active NVE.

   MAC Move can be used to optimize network convergence and reduce
   blackholes, when an active NVE hosting a logical L2 service fails
   over to a standby NVE.

   The protocol defined in this document addresses possible loss of the
   MAC Move messages due to network congestion, but does not guarantee
   delivery.

   In the event that MAC Move messages does not reach the intended
   target, the fallback to MAC re-learning or as a last resort aging out
   of MAC addresses in the absence of frames from the sources, will
   resume the traffic via new active NVE.

1.1  Terminology

   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].

1.2 Abbreviations

      NVO3 Network Virtualization Overlays over Layer 3

      OAM Operations, Administration, and Maintenance

      TLV Type, Length, and Value

      VNI Virtual Network Identifier

      NVE Network Virtualization Edge



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      NVA Network Virtualization Authority

      NIC Network interface card

      VTEP Virtual Tunnel End Point

      Transit device Underlay network devices between NVE(s).












































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2. MAC Move Frame Format

      Geneve 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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Ver|  Opt Len  |O|C|    Rsvd.  |          Protocol Type        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |        Virtual Network Identifier (VNI)       |    Reserved   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Geneve Option Header:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          Option Class         |      Type     |R|R|R| Length  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                      Variable Option Data                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      Option Class = To be assigned by IANA (TBA).

      Type = TBA.

      'C' bit, Endpoints must drop if they do not recognize this option)

      Length = 2 (8 bytes)

      Variable option data:


      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Version|Flags      |A|R|        old active VTEP ID             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Reserved               |        new active VTEP ID             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Sequence Number                                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



      Version (4 bits): Initially the Version will be 0.

      A (1 bit): Set by a receiver to acknowledge receipt and processing
      of a MAC Move message.



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      R (1 bit): Set to indicate if the sender is requesting reset of
      the sequence numbers. The sender sets this bit when it has no local
      record of previous send and expected receive sequence numbers.

      Flags(6): Reserved and should be set to 0.

      VTEP ID (20 bits): Identifies old and new active NVE(s).

      Sequence Number (32) bits: For overflow detection a sequence number
      that exceeds (0x7FFFFFFF) is considered an overflow and
      reset to 1.


3. Operation

   This section describes how the initial MAC Move Messages are sent and
   retransmitted, as well as how the messages are processed and
   retransmitted messages are identified. The mechanisms described are
   very similar to the one defined in [RFC 7769].

3.1 Operation of Sender

   At the NVE , each L2 logical switch identified by a VNI is associated
   with a counter to keep track of the sequence number of the
   transmitted MAC Move messages.  Whenever a node sends a MAC Move
   message, it increments the transmitted sequence-number counter and
   includes the new sequence number in the message.

   The transmit sequence number is initialized to 1 at the onset, after
   the wrap and after the sequence number reset request receipt. Hence
   the transmit sequence number is set to 2 in the first MAC Move
   message sent after the sequence number is initialized to 1.

   The sender expects an ACK from the receiver within a retransmit time
   interval, which can be either a default (1 second) or a configured
   value.  If the ACK is not received within the Retransmit time, the
   sender retransmits the message with the same sequence number as the
   original message.  The retransmission MUST cease when an ACK is
   received.  In order to avoid continuous re-transmissions in the
   absence of acknowledgements, the sender MUST cease retransmission
   after a small number of transmissions, two retries is RECOMMENDED.

   Alternatively, an increasing backoff delay with a larger number of
   retries MAY be implemented to improve scaling issues.

   During the period of retransmission, if a need to send a new MAC Move
   message with updated sequence number arises, then retransmission of
   the older unacknowledged Move message MUST be suspended and



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   retransmit time for the new sequence number MUST be initiated.  In
   essence, a sender engages in retransmission logic only for the most
   recently sent Move message for a given L2 Logical Switch identified
   by a VNI.

   In the event that the L2 logical switch is deleted and re-added or
   the VTEP node is restarted with new configuration, the NVE may lose
   information about the previously sent sequence number.  This becomes
   problematic for the remote peer as it will continue to ignore the
   received MAC Move messages with lower sequence numbers.  In such
   cases, it is desirable to reset the sequence numbers, the reset R-bit
   is set in the first MAC Move to notify the remote peer to reset the
   send and receive sequence numbers.  The R-bit must be cleared in
   subsequent MAC Move messages after the acknowledgement is received.

3.2 Operation of Receiver

   Each L2 logical switch identified by a VNI is associated with a
   receive sequence number per remote NVE to keep track of the expected
   sequence number of the MAC Move message.

   Whenever a MAC Move message is received, and if the sequence number
   on the message is greater than the value in the receive sequence
   number of this remote NVE, the MAC addresses learned from the NVE
   associated with the NVE identifier in the message are moved to be
   associated with the new active NVE identifier, and the receive
   sequence number of the remote NVE is updated with the received
   sequence number.  The receiver sends an ACK with the same sequence
   number in the received message.

   If the sequence number in the received message is smaller than or
   equal to the value in the receive sequence number per remote NVE, the
   MAC Move is not processed. However, an ACK with the received sequence
   number MUST be sent as a response to stop the sender retransmission.

   A MAC Move message with the R-bit set MUST be processed by resetting
   the receive sequence number of the remote NVE, and Moving the MACs as
   described above. The acknowledgement is sent with the R-bit cleared.

4. Security Considerations

   This document does not introduce any additional security constraints.

5. IANA Considerations
      IANA is requested to assign a new option class from the "Geneve
      Option Class" registry for the Geneve MAC Move option.

      Option Class    Description



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      ------------    ---------------------
         XXXX         Geneve MAC Move


6  References

6.1  Normative References

   [KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", BCP 14, RFC 2119, March 1997.

6.2  Informative References

   [Geneve] "Generic Network Virtualization Encapsulation", [I-D.ietf-
   nvo3-geneve]
   [RFC 7769] "MAC Address Withdrawal over Static PW", [RFC 7769]




Authors' Addresses


   Sami Boutros
   VMware
   Email: boutross@vmware.com

   Jerome Catrouillet
   VMware
   Email: jcatrouillet@vmware.com

   Ankur Sharma
   VMware
   Email: ankursharma@vmware.com

















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