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

Versions: 00 01 02 draft-kouvelas-lisp-map-server-reliable-transport

Network Working Group                                          C. Cassar
Internet-Draft                                               I. Kouvelas
Intended status: Experimental                                   D. Lewis
Expires: September 27, 2015                                Cisco Systems
                                                          March 26, 2015


                        LISP Reliable Transport
             draft-kouvelas-lisp-reliable-transport-02.txt

Abstract

   The communication between LISP ETRs and Map-Servers is based on
   unreliable UDP message exchange coupled with periodic message
   transmission in order to maintain soft state.  The drawback of
   periodic messaging is the constant load imposed on both the ETR and
   the Map-Server.  New use cases for LISP have increased the amount of
   state that needs to be communicated with requirements that are not
   satisfied by the current mechanism.  This document introduces the use
   of a reliable transport for ETR to Map-Server communication in order
   to eliminate the periodic messaging overhead, while providing
   reliability, flow-control and endpoint liveness detection.

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 September 27, 2015.

Copyright Notice

   Copyright (c) 2015 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



Cassar, et al.         Expires September 27, 2015               [Page 1]


Internet-Draft           LISP Reliable Transport              March 2015


   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.  Requirements Notation . . . . . . . . . . . . . . . . . . . .   3
   3.  Message Format  . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Session Establishment . . . . . . . . . . . . . . . . . . . .   5
   5.  Error Notifications . . . . . . . . . . . . . . . . . . . . .   5
   6.  EID Prefix Registration . . . . . . . . . . . . . . . . . . .   7
     6.1.  Reliable Mapping Registration Messages  . . . . . . . . .   7
       6.1.1.  Registration Message  . . . . . . . . . . . . . . . .   7
       6.1.2.  Registration Acknowledgement Message  . . . . . . . .   8
       6.1.3.  Registration Rejected Message . . . . . . . . . . . .   9
       6.1.4.  Registration Refresh Message  . . . . . . . . . . . .   9
       6.1.5.  Mapping Notification Message  . . . . . . . . . . . .  10
     6.2.  ETR Behavior  . . . . . . . . . . . . . . . . . . . . . .  11
     6.3.  Map-Server Behavior . . . . . . . . . . . . . . . . . . .  15
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
     8.1.  LISP Reliable Transport Message Types . . . . . . . . . .  16
     8.2.  Transport Protocol Port Numbers . . . . . . . . . . . . .  16
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  16
   10. Normative References  . . . . . . . . . . . . . . . . . . . .  17
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   The communication channel between LISP ETRs and Map-Servers is based
   on unreliable UDP message exchange [RFC6833].  Where required,
   reliability is pursued through periodic retransmissions that maintain
   soft state on the peer.  Map-Register messages are retransmitted
   every minute by an ETR and the Map-Server times out its state if the
   state is not refreshed for three successive periods.  When
   registering multiple EID-Prefixes, the ETR includes multiple mapping
   records in the Map-Register message.  Packet size limitations provide
   an upper bound to the number of mapping records that can be placed in
   each Map-Register message.  When the ETR has more EID-Prefixes to
   register than can be packed in a single Map-Register message, the
   mapping records for the EID-Prefixes are split across multiple Map-
   Register messages.





Cassar, et al.         Expires September 27, 2015               [Page 2]


Internet-Draft           LISP Reliable Transport              March 2015


   The drawback of the periodic registration is the constant load that
   it introduces on both the ETR and the Map-Server.  The ETR uses
   resources to periodically build and transmit the Map-Register
   messages, and to process the resulting Map-Notify messages issued by
   the Map-Server.  The Map-Server uses resources to process the
   received Map-Register messages, update the corresponding registration
   state, and build and transmit the matching Map-Notify messages.  When
   the number of EID-Prefixes to be registered by an ETR is small, the
   resulting load imposed by periodic registrations may not be
   significant.  The ETR will only transmit a single Map-Register
   message each period that contains a small number of mapping records.

   In some LISP deployments, a large set of EID-Prefixes must be
   registered by each ETR (e.g. mobility, database redistribution).  Use
   cases with a large set of EID-Prefixes behind an ETR will result in a
   much higher load.  An example is LISP mobility deployments where EID-
   Prefixes are limited to host entries.  ETRs may have thousands of
   hosts to register resulting in hundreds of Map-Register and Map-
   Notify messages per registration period.

   A transport is required for the ETR to Map-Server communication that
   provides reliability, flow-control and endpoint liveness
   notifications.  This document describes the use of TCP or SCTP as a
   LISP reliable transport.  The initial application for the LISP
   reliable transport session is the support of scalable EID prefix
   registration.  The reliable session mechanism is defined to be
   extensible so that it can support additional LISP communication
   requirements as they arise using a single reliable transport session
   between an ETR and a Map-Server.  The use of the reliable transport
   session for EID prefix registration is an alternative and does not
   replace the existing UDP based mechanism.

2.  Requirements Notation

   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].

3.  Message Format

   A single LISP reliable transport session may carry information for
   multiple LISP applications.  One such application is the registration
   of EID to RLOC mappings that operates over a session between an ETR
   and a Map-Server.  Communication over a session is based on the
   exchange of messages.  This document defines a base set of messages
   to support session establishment and management.  It also defines the
   messages for the EID to RLOC mapping registration application.




Cassar, et al.         Expires September 27, 2015               [Page 3]


Internet-Draft           LISP Reliable Transport              March 2015


   To support protocol extensibility when new applications, or
   extensions to existing applications are introduced, the messages are
   based on a TLV format.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |             Type              |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Message ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Message Data                       ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Message End Marker                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Reliable transport message format

   o  Type: 16 bit type field identifying the message type.

   o  Length: 16 bit field that provides the total size of the message
      in octets including the length, type and end marker fields.  The
      length allows the receiver to locate the next message in the TCP
      stream.  The minimum value of the length field is 8.

   o  ID: A 32-bit value that identifies the message.  May be used by
      the receiver to identify the message in replies or notification
      messages.

   o  Data: Type specific message contents.

   o  End Marker: A 32-bit message end marker that must be set to
      0x9FACADE9.  The End Marker is used by the receiver to validate
      that it has correctly parsed or skipped a message and provides a
      method to detect formatting errors.  Note that message data may
      also contain this marker, and that the marker itself is not
      sufficient for parsing the message.

   The base message format does not indicate how the peer should deal
   with the message in cases where the message type is not supported/
   understood.  This is best dealt with by the application.  For
   example, in case an error notification is returned, or an expected
   acknowledgement message is not received, the application might choose
   various courses of action; from simply logging that the feature is
   not supported, all the way to tearing the relationship with the peer
   down for the feature, or for all LISP features.





Cassar, et al.         Expires September 27, 2015               [Page 4]


Internet-Draft           LISP Reliable Transport              March 2015


4.  Session Establishment

   The LISP router that performs the active open initiates the
   connection from a locally generated source transport port number to
   the well-known destination transport port assigned to LISP.  The LISP
   router that performs the passive open listens on the well-known local
   transport port and does not qualify the remote transport port number.
   In the ETR to Map-Server reliable transport session, the ETR assumes
   the active role and the Map-Server passively accepts connections.

   A single reliable transport session can be established between a pair
   of LISP peers to cover all communication needs.  For example, an ETR
   that has EID prefix registrations for multiple EID instances and EID
   address families might only establish a single session with the Map-
   Server.

   When using TCP and symmetric connection establishment LISP must
   perform collision detection and duplicate session elimination.  To
   accomplish that, LISP peer ID messages will be exchanged between the
   peers once a session is established.  If duplicate sessions are
   detected then the one that was initiated by the router with the
   higher ID is kept and the other session is torn down.  TBD

5.  Error Notifications

   The error notification message is used to communicate base reliable
   transport session communication errors.  LISP applications making use
   of the reliable transport session and having to communicate
   application specific errors must define their own messages to do so.
   An error notification is issued when the receiver of a message does
   not recognize the message type or cannot parse the message contents.
   The notification includes the offending message type and ID and as
   much of the offending message data as the notification sender wishes
   to.

















Cassar, et al.         Expires September 27, 2015               [Page 5]


Internet-Draft           LISP Reliable Transport              March 2015


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type = 16           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Message ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Error Code    |                   Reserved                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Offending Message Type     |    Offending Message Length   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                     Offending Message ID                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Offending Message Data                   ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Message End Marker                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                     Error notification message format

   o  Error Code: An 8 bit field identifying the type of error that
      occurred.  Defined errors are:

      *  Unrecognized message type.

      *  Message format error.

   o  Reserved: Set to zero by the sender and ignored by the receiver.

   o  Offending Message Type: 16 bit type field identifying the message
      type of the offending message that triggered this error
      notification.  This is copied from the Type field of the offending
      message.

   o  Offending Message Length: 16 bit field that provides the total
      size of the offending message in octets.  This is copied from the
      Length field of the offending message.

   o  Offending Message ID: A 32-bit field that is set to the Message ID
      field of the offending message.

   o  Offending Message Data: The Data from the offending message that
      triggered this error notification.  The sender of the notification
      may include as much of the original data as is deemed necessary.
      The length of the Offending Message Data field is not provided by
      the Offending Message Length field and is determined by
      subtracting the size of the other fields in the message from the




Cassar, et al.         Expires September 27, 2015               [Page 6]


Internet-Draft           LISP Reliable Transport              March 2015


      Length field.  It is valid to not include any of the offending
      message data when sending an error notification.

   o  End Marker: A 32-bit message end marker that must be set to
      0x9FACADE9.  The End Marker is used by the receiver to validate
      that it has correctly parsed or skipped a message and provides a
      method to detect formatting errors.  Note that message data may
      also contain this marker, and that the marker itself is not
      sufficient for parsing the message.

   An error notification cannot be the offending message in another
   error notification and MUST NOT trigger such a message.

6.  EID Prefix Registration

   EID prefix registration uses the reliable transport session between
   an ETR and a Map-Server to communicate the ETR local EID database EID
   to RLOC mappings to the Map-Server.  In contrast to the UDP based
   periodic registration, mapping information over the reliable
   transport session is only sent when there is new information
   available for the Map-Server.  The Map-Server does not maintain a
   timer to expire registrations communicated over the reliable
   transport session.  Instead an explicit de-registration (a
   registration carrying a zero TTL) is needed to delete the state
   maintained by the Map-Server.

   The key used to identify registration mapping records in the ETR to
   Map-Server communication is the EID prefix.  The prefix may be
   specified using an LCAF encoding that includes an EID instance ID.

   When the reliable transport session goes down, registration mappings
   learned by the Map-Server are treated as periodic UDP registrations
   and a timer is used to expire them after 3 minutes.  During this
   period UDP based registrations or the re-establishment of the
   reliable transport session and subsequent communication of a new
   mapping can update the EID prefix mapping state.

6.1.  Reliable Mapping Registration Messages

   This section defines the LISP reliable transport session messages
   used to communicate local EID database registrations between the ETR
   and the Map-Server.

6.1.1.  Registration Message

   The reliable transport Registration message is used to communicate
   EID to RLOC mapping registrations from the ETR to the Map-Server.
   The Registration message uses exactly the same format as the UDP Map-



Cassar, et al.         Expires September 27, 2015               [Page 7]


Internet-Draft           LISP Reliable Transport              March 2015


   Register message but instead of the IP/UDP header, the Map-Register
   is placed within the value section of the reliable transport TLV.  A
   common message format is proposed to leverage the authentication
   features built into the UDP Map-Register message and increase code
   reuse.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type = 17           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Message ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                      Map-Register message                   ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ...                    Map-Register message                     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Message End Marker                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Registration message format

6.1.2.  Registration Acknowledgement Message

   The Acknowledgement message is sent from the Map-Server to the ETR to
   confirm successful registration of an EID prefix previously
   communicated by a reliable transport session Registration message.
   The Registration Acknowledgement message does not carry a mapping
   record (the map servers view of the mapping).  This is accomplished
   by the LISP reliable transport Map Notification message.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type = 18           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Message ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        EID-Prefix-AFI         |           EID-Prefix        ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Message End Marker                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Registration Acknowledgement message format

   o  EID-Prefix AFI: Address family identifier for the EID prefix in
      the following field.




Cassar, et al.         Expires September 27, 2015               [Page 8]


Internet-Draft           LISP Reliable Transport              March 2015


   o  EID-Prefix: The EID prefix from the received Registration.

6.1.3.  Registration Rejected Message

   Negative acknowledgement sent from the Map-Server to the ETR to
   indicate that the registration of a specific EID prefix was rejected.
   The ETR must keep track of the fact that the registration of the EID
   prefix was rejected by the Map-Server and be prepared to re-register
   the mapping when requested through a failed Registration Refresh
   request.

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type = 19           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Message ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Rejection code         |        EID-Prefix-AFI         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          EID-Prefix                         ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Message End Marker                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Registration Rejected message format

   o  Rejection code: Code identifying the reason for which the Map-
      Server rejected the registration.  Codes:

      *  1 - Not a valid site EID prefix.

      *  2 - Authentication failure.

      *  3 - Locator set not allowed.

   o  EID-Prefix AFI: Address family identifier for the EID prefix in
      the following field.

   o  EID-Prefix: The EID prefix from the received Registration.

6.1.4.  Registration Refresh Message

   Sent by the Map-Server to the ETR to request the re-transmission of
   EID prefix database mapping Registration messages.






Cassar, et al.         Expires September 27, 2015               [Page 9]


Internet-Draft           LISP Reliable Transport              March 2015


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type = 20           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Message ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |R|          Reserved           |        EID-Prefix-AFI         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          EID-Prefix                         ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Message End Marker                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                    Registration Refresh message format

   o  R: Request from the ETR to only refresh registrations that have
      been previously rejected by the Map-Server.

   o  EID prefix, and its more specifics, to refresh.  The prefix can be
      in LCAF format allowing specification of a complete refresh
      (unspecified prefix), refresh of all the prefixes under an EID
      instance or even of more specific registrations under a specific
      EID prefix.

6.1.5.  Mapping Notification Message

   Mapping Notification messages communicate the Map-Server view of the
   mapping for an EID prefix and no longer serve as a registration
   acknowledgement.  Mapping Notifications do not need message level
   authentication as they are received over a reliable transport session
   to a known Map-Server.  Note that reliable transport Mapping
   Notification messages do not reuse the UDP Map-Notify message format.


















Cassar, et al.         Expires September 27, 2015              [Page 10]


Internet-Draft           LISP Reliable Transport              March 2015


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           Type = 21           |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                           Message ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Mapping Record                      ...
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ...                       Mapping Record                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Message End Marker                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Registration message format

6.2.  ETR Behavior

   The ETR operates the following per EID prefix, per MS state machine
   that defines the reliable transport EID prefix registration behavior.

   There are five states:

   o  No state: The local EID database prefix does not exist.

   o  Periodic: The local EID database prefix is being periodically
      registered through UDP Map-Register messages as specified in [].

   o  Stable: From the ETR's perspective, no registrations are due to be
      sent to the peer.  The session to the peer is up, and the peer has
      either acknowledged the registration, or is expected to request a
      refresh in the future.

   o  AckWait: A Registration message for the prefix has been
      transmitted to the Map-Server and the ETR is waiting for either a
      Registration Acknowledge or Registration Rejected reply from the
      Map-Server.

   o  Reject: The reliable transport registration for the local EID
      database prefix was rejected by the Map-Server.  From the ETR's
      perspective, no registration is due to the peer AND the peer is
      known to have rejected the registration.

   The following events drive the state transitions:

   o  DB creation: The local EID database entry for the EID prefix is
      created.




Cassar, et al.         Expires September 27, 2015              [Page 11]


Internet-Draft           LISP Reliable Transport              March 2015


   o  DB deletion: The local EID database entry for the EID prefix is
      deleted.

   o  DB change: The mapping contents or authentication information for
      the local EID database entry changes.

   o  Session up: The reliable transport session to the Map-Server is
      established.

   o  Session down: The reliable transport session the Map-Server goes
      down.

   o  Recv Refresh: A Registration refresh message is received from the
      Map-Server.

   o  Recv ACK: A Registration Acknowledge message is received from the
      Map-Server.

   o  Recv Rejected: A Registration Rejected message is received from
      the Map-Server.

   o  Periodic timer: The timer that drives generation of periodic UDP
      Map-Register messages fires.

   The state machine is:


























Cassar, et al.         Expires September 27, 2015              [Page 12]


Internet-Draft           LISP Reliable Transport              March 2015


   +--------------------+--------------------------------------+
   |                    |              Prev State              |
   |  Event             +-------------------+------------------+
   |                    |   No state        |    Periodic      |
   +--------------------+-------------------+------------------+
   |  DB creation       |   -> Periodic     |    N/A           |
   |  [session down]    |   A1              |                  |
   +--------------------+-------------------+------------------+
   |  DB creation       |   -> AckWait      |    N/A           |
   |  [session up]      |   A2              |                  |
   +--------------------+-------------------+------------------+
   |  DB deletion       |   N/A             |    -> No state   |
   |                    |                   |    A3            |
   +--------------------+-------------------+------------------+
   |  DB change         |   N/A             |    -             |
   |                    |                   |    A1            |
   +--------------------+-------------------+------------------+
   |  Session up        |   -               |    -> Stable     |
   |                    |                   |    A4            |
   +--------------------+-------------------+------------------+
   |  Session down      |   -               |    N/A           |
   |                    |                   |                  |
   +--------------------+-------------------+------------------+
   |  Recv Refresh      |   -               |    N/A           |
   |                    |                   |                  |
   +--------------------+-------------------+------------------+
   |  Recv Refresh      |   -               |    N/A           |
   |  [rejected]        |                   |                  |
   +--------------------+-------------------+------------------+
   |  Recv ACK          |   -               |    N/A           |
   |                    |                   |                  |
   +--------------------+-------------------+------------------+
   |  Recv Rejection    |   -               |    N/A           |
   |                    |                   |                  |
   +--------------------+-------------------+------------------+
   |  Timer             |   N/A             |    -             |
   |                    |                   |    A5            |
   +--------------------+-------------------+------------------+

                  xTR per EID prefix per MS state machine











Cassar, et al.         Expires September 27, 2015              [Page 13]


Internet-Draft           LISP Reliable Transport              March 2015


   +-----------------+-----------------------------------------------+
   |                 |                   Prev State                  |
   | Event           +---------------+---------------+---------------+
   |                 |    Stable     |   AckWait     |   Rejected    |
   +-----------------+---------------+---------------+---------------+
   | DB creation     | N/A           | N/A           | N/A           |
   |                 |               |               |               |
   +-----------------+---------------+---------------+---------------+
   | DB deletion     | -> No state   | -> No state   | -> No state   |
   |                 | A6            | A6            |               |
   +-----------------+---------------+---------------+---------------+
   | DB change       | -> AckWait    | -             | -> AckWait    |
   |                 | A2            | A2            | A2            |
   +-----------------+---------------+---------------+---------------+
   | Session up      | N/A           | N/A           | N/A           |
   |                 |               |               |               |
   +-----------------+---------------+---------------+---------------+
   | Session down    | -> Periodic   | -> Periodic   | -> Periodic   |
   |                 | A7            | A7            | A7            |
   +-----------------+---------------+---------------+---------------+
   | Recv Refresh    | -> AckWait    | -             | -> AckWait    |
   |                 | A2            | A2            | A2            |
   +-----------------+---------------+---------------+---------------+
   | Recv Refresh    | -             | -             | -> AckWait    |
   | [rejected]      |               | A2            | A2            |
   +-----------------+---------------+---------------+---------------+
   | Recv ACK        | -             | -> Stable     | -> AckWait    |
   |                 |               |               | A2            |
   +-----------------+---------------+---------------+---------------+
   | Recv Rejection  | -> Rejected   | -> Rejected   | -             |
   |                 |               |               |               |
   +-----------------+---------------+---------------+---------------+
   | Timer           | N/A           | N/A           | N/A           |
   |                 |               |               |               |
   +-----------------+---------------+---------------+---------------+

                  xTR per EID prefix per MS state machine

   Action descriptions:

   o  A1: Start periodic registration timer with zero delay.

   o  A2: Send Registration over reliable transport session.

   o  A3: Send UDP registration with zero TTL.

   o  A4: Stop periodic registration timer.




Cassar, et al.         Expires September 27, 2015              [Page 14]


Internet-Draft           LISP Reliable Transport              March 2015


   o  A7: Send UDP registration and start periodic registration timer
      with registration period.

   o  A6: Send Registration with TTL zero over reliable transport
      session.

   o  A7: Start periodic registration timer with registration period.

   All timer start actions must be jittered.

   When the reliable transport session is established the state machine
   moves into the Stable state without first registering the EID prefix
   over the reliable transport session.  The subsequent refresh issued
   by the Map-Server will trigger the registration message to be sent.
   This model will allow future optimisations where the Map-Server may
   retain registration state from a previous instantiation of the
   reliable transport session with the ETR and only request the refresh
   of EID prefix state beyond some negotiated session progress marker.

   Aa Map-Server authentication key change is treated as a DB change
   event and will result in triggering a new Registration message to be
   transmitted.

6.3.  Map-Server Behavior

   Received registrations create/update or delete mapping state.

   A refresh for an unspecified prefix is sent when a session is first
   established to obtain the complete database contents from the ETR.

   Refresh for rejected registrations sent (R bit set) when a new EID
   prefix is configured on the Map-Server.

   Rejection sent to the ETR when an EID prefix that is registered is
   deconfigured.

   Rejected Refresh (R bit set) sent when authentication for an EID
   prefix changes followed by a Rejection for existing registrations
   which fail authentication following change.

   Mapping Notification message sent whenever the mapping for a
   registered or more specific prefix for which notifications are
   requested changes.  ETR acknowledgement or rejection messaging for
   Mapping Notification is not required because the ETR decides how to
   process the message based on the registered mapping information.  If
   the mapping information changes the resulting registration will
   trigger a new Mapping Notification message from the Map-Server.




Cassar, et al.         Expires September 27, 2015              [Page 15]


Internet-Draft           LISP Reliable Transport              March 2015


7.  Security Considerations

   The LISP reliable transport session SHOULD be authenticated.  On
   controlled RLOC networks that can guarantee that the source RLOC
   address of data packets cannot be spoofed, the authentication check
   can be a source address validation on the reliable transport packets.
   When the RLOC network does not provide such guarantees, reliable
   transport authentication SHOULD be used.  Implementations SHOULD
   support the TCP Authentication Option (TCP-AO) [RFC5925] and SCTP
   Authenticated Chunks [RFC4895].

8.  IANA Considerations

8.1.  LISP Reliable Transport Message Types

   Assignment of new LISP reliable transport message types is done
   according to the "IETF Review" model defined in [RFC5266].

   The initial content of the registry should be as follows.

   Type         Name                                      Reference
   -----------  ----------------------------------------  --------------
   0-15         Reserved                                  This document
   16           Error Notification                        This document
   17           Registration Message                      This document
   18           Registration Acknowledgement Message      This document
   19           Registration Rejected Message             This document
   20           Registration Refresh Message              This document
   21           Mapping Notification Message              This document
   22-30        Reserved for EID membership distribution  TBD
   31-64999     Unassigned
   65000-65535  Reserved for Experimental Use

8.2.  Transport Protocol Port Numbers

   TCP port 4342 already reserved for LISP CONS that is now obsolete.
   Repurpose for reliable transport over TCP.  Reserve an SCTP port.

9.  Acknowledgments

   The authors would like to thank Noel Chiappa, Dino Farinacci, Jesper
   Skriver, Johnson Leong, Andre Pelletier and Les Ginsberg for their
   contributions to this document.








Cassar, et al.         Expires September 27, 2015              [Page 16]


Internet-Draft           LISP Reliable Transport              March 2015


10.  Normative References

   [I-D.ietf-lisp-lcaf]
              Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical
              Address Format (LCAF)", draft-ietf-lisp-lcaf-07 (work in
              progress), December 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5266]  Devarapalli, V. and P. Eronen, "Secure Connectivity and
              Mobility Using Mobile IPv4 and IKEv2 Mobility and
              Multihoming (MOBIKE)", BCP 136, RFC 5266, June 2008.

   [RFC6830]  Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
              Locator/ID Separation Protocol (LISP)", RFC 6830, January
              2013.

   [RFC6833]  Fuller, V. and D. Farinacci, "Locator/ID Separation
              Protocol (LISP) Map-Server Interface", RFC 6833, January
              2013.

Authors' Addresses

   Chris Cassar
   Cisco Systems
   10 New Square Park
   Bedfont Lakes, Feltham  TW14 8HA
   United Kingdom

   Email: ccassar@cisco.com


   Isidor Kouvelas
   Cisco Systems
   Monumental Plaza, Building C
   44 Kifissias Ave.
   Maroussi, Athens  15125
   Greece

   Email: kouvelas@cisco.com










Cassar, et al.         Expires September 27, 2015              [Page 17]


Internet-Draft           LISP Reliable Transport              March 2015


   Darrel Lewis
   Cisco Systems
   Tasman Drive
   San Jose, CA  95134
   USA

   Email: darlewis@cisco.com












































Cassar, et al.         Expires September 27, 2015              [Page 18]


Html markup produced by rfcmarkup 1.129d, available from https://tools.ietf.org/tools/rfcmarkup/