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Versions: (draft-rodrigueznatal-lisp-pubsub) 00

LISP Working Group                                    A. Rodriguez-Natal
Internet-Draft                                                V. Ermagan
Intended status: Experimental                                   J. Leong
Expires: October 27, 2018                                       F. Maino
                                                           Cisco Systems
                                                    A. Cabellos-Aparicio
                                       Technical University of Catalonia
                                                               S. Barkai
                                                        Fermi Serverless
                                                            D. Farinacci
                                                             lispers.net
                                                            M. Boucadair
                                                            C. Jacquenet
                                                                  Orange
                                                                S. Secci
                                                               LIP6 UPMC
                                                          April 25, 2018


                Publish/Subscribe Functionality for LISP
                       draft-ietf-lisp-pubsub-00

Abstract

   This document specifies an extension to the use of Map-Request to
   enable Publish/Subscribe (PubSub) operation for LISP.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on October 27, 2018.








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Copyright Notice

   Copyright (c) 2018 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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   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 Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Deployment Assumptions  . . . . . . . . . . . . . . . . . . .   3
   4.  Map-Request Additions . . . . . . . . . . . . . . . . . . . .   4
   5.  Mapping Request Subscribe Procedures  . . . . . . . . . . . .   5
   6.  Mapping Notification Publish Procedures . . . . . . . . . . .   7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .   8
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   10. Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Locator/ID Separation Protocol (LISP) [RFC6830] splits current IP
   addresses in two different namespaces, Endpoint Identifiers (EIDs)
   and Routing Locators (RLOCs).  LISP uses a map-and-encap approach
   that relies on (1) a Mapping System (basically a distributed
   database) that stores and disseminates EID-RLOC mappings and on (2)
   LISP tunnel routers (xTRs) that encapsulate and decapsulate data
   packets based on the content of those mappings.

   ITRs/RTRs/PITRs pull EID-to-RLOC mapping information from the Mapping
   System by means of an explicit request message.  [RFC6830] indicates
   how ETRs can tell ITRs/RTRs/PITRs about mapping changes.  This
   document presents a Publish/Subscribe (PubSub) extension in which the
   Mapping System can notify ITRs/RTRs/PITRs about mapping changes.
   When this mechanism is used, mapping changes can be notified faster
   and can be managed in the Mapping System versus the LISP sites.





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   In general, when an ITR/RTR/PITR wants to be notified for mapping
   changes for a given EID-prefix, the following steps occur:

   (1)  The ITR/RTR/PITR sends a Map-Request for that EID-prefix.

   (2)  The ITR/RTR/PITR sets the Notification-Requested bit (N-bit) on
        the Map-Request and includes its xTR-ID.

   (3)  The Map-Request is forwarded to one of the Map-Servers that the
        EID-prefix is registered to.

   (4)  The Map-Server creates subscription state for the ITR/RTR/PITR
        on the EID-prefix.

   (5)  The Map-Server sends a Map-Notify to the ITR/RTR/PITR to
        acknowledge the successful subscription.

   (6)  When there is an RLOC-set change for the EID-prefix, the Map-
        Server sends a Map-Notify message to each ITR/RTR/PITR in the
        subscription list.

   (7)  Each ITR/RTR/PITR sends a Map-Notify-Ack to acknowledge the
        received Map-Notify.

   This operation is repeated for all EID-prefixes for which ITR/RTR/
   PITR want to be notified.  The ITR/RTR/PITR can set the N-bit for
   several EID-prefixes within a single Map-Request

2.  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].

3.  Deployment Assumptions

   The specification described in this document makes the following
   deployment assumptions:

   (1)  A unique 128-bit xTR-ID identifier is assigned to each xTR.

   (2)  Map-Servers are configured in proxy-reply mode, i.e., they are
        solicited to generate and send Map-Reply messages for the
        mappings they are serving.

   (3)  There can be either a soft-state or hard-state security
        association between the xTRs and the Map-Servers.




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   The distribution of xTR-IDs and the management of security
   associations are out of the scope of this document.







4.  Map-Request Additions

   Figure 1 shows the format of the updated Map-Request
   [I-D.ietf-lisp-rfc6833bis] to support the PubSub functionality.

        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=1 |A|M|P|S|p|s|m|I|   Reserved  |   IRC   | Record Count  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         Nonce . . .                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                         . . . Nonce                           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         Source-EID-AFI        |   Source EID Address  ...     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         ITR-RLOC-AFI 1        |    ITR-RLOC Address 1  ...    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                              ...                              |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |         ITR-RLOC-AFI n        |    ITR-RLOC Address n  ...    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     / |N|   Reserved  | EID mask-len  |        EID-Prefix-AFI         |
   Rec +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     \ |                       EID-Prefix  ...                         |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Map-Reply Record  ...                       |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       +                                                               +
       |                                                               |
       +                            xTR-ID                             +
       |                                                               |
       +                                                               +
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                Figure 1: Map-Request with N-bit and xTR-ID




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   The meaning of the fields is exactly the same as defined in
   [I-D.ietf-lisp-rfc6833bis].  The only addition is a flag bit in the
   EID-Record field.  The meaning of this flag bit is as follows:

      Notification-Requested bit (N-bit): the first bit in the EID-
      Record section of a Map-Request message.  The N-bit of an EID-
      record is set to 1 to specify that the xTR wants to be notified of
      updates for that mapping record.

   The PubSub functionality requires to include an xTR-ID in the Map-
   Request.  This is done by setting the xTR-ID bit (I-bit) defined in
   [I-D.ietf-lisp-rfc6833bis].  When the I-bit of a Map-Request message
   is set, a 128-bit xTR-ID field is appended to the end of the Map-
   Request, immediately following the last EID-Record (or the Map-Reply
   Record, if present).  The xTR-ID field uniquely identifies each xTR
   of a given LISP deployment.  Provisioning of unique xTR-IDs is out of
   the scope of this document.

5.  Mapping Request Subscribe Procedures

   The xTR subscribes for RLOC-set changes for a given EID-prefix by
   sending a Map-Request to the Mapping System with the N-bit set on the
   EID-Record.  The xTR builds a Map-Request according to [RFC6830] but
   also does the following:

   (1)  The xTR MUST set the I-bit of the Map-Request message to 1, to
        specify the presence of an xTR-ID field that uniquely identifies
        the xTR.

   (2)  The xTR MUST set the N-bit to 1 for each EID-Record to which the
        xTR wants to subscribe.

   The Map-Request is forwarded to the appropriate Map-Server through
   the Mapping System.  This document does not assume that a Map-Server
   is pre-assigned to handle the subscription state for a given xTR.
   The Map-Server that receives the Map-Request will be the Map-Server
   responsible to notify that specific xTR about future mapping changes
   for the subscribed mapping records.

   Upon reception of the Map-Request, the Map-Server processes it as
   described in [RFC6830].  Upon processing, for each EID-Record that
   has the N-bit set to 1, the Map-Server proceeds adding the xTR-ID
   contained in the Map-Request to the list of xTR that have requested
   to be subscribed to that mapping record.

   If the xTR-ID is added to the list, the Map-Server MUST send a Map-
   Notify message back to the xTR to acknowledge the successful
   subscription.  The Map-Server MUST follow the specification in



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   Section 6.1.7 of [RFC6830] to build the Map-Notify with the following
   considerations.

   (1)  The Map-Server MUST use the nonce from the Map-Request as the
        nonce for the Map-Notify.

   (2)  The Map-Server MUST use its security association with the xTR
        (see Section 3) to compute the authentication data of the Map-
        Notify.

   (3)  The Map-Server MUST send the Map-Notify to one of the ITR-RLOCs
        received in the Map-Request.

   When the xTR receives a Map-Notify with a nonce that matches one in
   the list of outstanding Map-Request messages sent with an N-bit set,
   it knows that the Map-Notify is to acknowledge a successful
   subscription.  The xTR processes this Map-Notify as described in
   [RFC6830] with the following considerations.  The xTR MUST use its
   security association with the Map-Server (see Section 3) to validate
   the authentication data on the Map-Notify.  The xTR MUST use the Map-
   Notify to populate its map-cache with the returned EID-prefix and
   RLOC-set.

   The subscription of an xTR-ID to the list of subscribers for the EID-
   Record may fail for a number of reasons.  For example, because of
   local configuration policies (such as white/black lists of
   subscribers), or because the Map-Server has exhausted the resources
   to dedicate to the subscription of that EID-Record (e.g., the number
   of subscribers excess the capacity of the Map-Server).

   If the subscription fails, the Map-Server MUST send a Map-Reply to
   the originator of the Map-Request, as described in [RFC6830].  This
   is also the case when the Map-Server does not support PubSub
   operation.  The xTR processes the Map-Reply as specified in
   [RFC6830].

   If an xTR-ID is successfully added to the list of subscribers for an
   EID-Record, the Map-Server MUST extract the ITR-RLOCs present in the
   Map-Request, and store the association between the xTR-ID and those
   RLOCs.  Any already present state regarding ITR-RLOCs for the same
   xTR-ID MUST be overwritten.

   If the Map-Request only has one ITR-RLOC with AFI = 0 (i.e.  Unknown
   Address), the Map-Server MUST remove the subscription state for that
   xTR-ID.  In this case, the Map-Server MUST send the Map-Notify to the
   source RLOC of the Map-Request.  When the TTL for the EID-record
   expires, the EID-prefix is removed from the Map-Server's subscription




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   cache.  On EID-Record removal, the Map-Server notifies the
   subscribers via a Map-Notify with TTL equal 0.

6.  Mapping Notification Publish Procedures

   The publish procedure is implemented via Map-Notify messages that the
   Map-Server sends to xTRs.  The xTRs acknowledge the reception of Map-
   Notifies via sending Map-Notify-Ack messages back to the Map-Server.
   The complete mechanism works as follows.

   When a mapping stored in a Map-Server is updated (e.g. via a Map-
   Register from an ETR), the Map-Server MUST notify the subscribers of
   that mapping via sending Map-Notify messages with the most updated
   mapping information.  The Map-Notify message sent to each of the
   subscribers as a result of an update event MUST follow the exact
   encoding and logic defined in [RFC6830] for Map-Notify, except for
   the following:

   (1)  The Map-Notify MUST be sent to one of the ITR-RLOCs associated
        with the xTR-ID of the subscriber.

   (2)  The nonce of the Map-Notify MUST be the one the subscriber sent
        in the Map-Request.  If the subscriber sent no Map-Request (e.g.
        was subscribed via configuration at the Map-Server) the nonce
        MUST be randomly generated by the Map-Server.

   (3)  The Map-Server MUST use its security association with the xTR to
        compute the authentication data of the Map-Notify.

   When the xTR receives a Map-Notify with a nonce sent previously in a
   Map-Request, or with a nonce not present in any list of previously
   sent nonces but with an EID not local to the xTR, the xTR knows that
   the Map-Notify has been received to update an entry on its map-cache.
   Processing of unsolicited Map-Notify messages MUST be explicitly
   enabled via configuration at the xTR.

   The xTR processes the received Map-Notify as specified in [RFC6830],
   with the following considerations.  The xTR MUST use its security
   association with the Map-Server (see Section 3) to validate the
   authentication data on the Map-Notify.  The xTR MUST use the mapping
   information carried in the Map-Notify to update its internal map-
   cache.  The xTR MUST acknowledge the Map-Notify by sending back a
   Map-Notify-Ack (specified in [I-D.ietf-lisp-rfc6833bis]), with the
   nonce from the Map-Notify, to the Map-Server.  If after a
   configurable timeout, the Map-Server has not received back the Map-
   Notify-Ack, it CAN try to send the Map-Notify to a different ITR-RLOC
   for that xTR-ID.




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7.  Security Considerations

   The way to provide a security association between the ITRs and the
   Map-Servers must be evaluated according to the size of the
   deployment.  For small deployments, it is possible to have a shared
   key (or set of keys) between the ITRs and the Map-Servers.  For
   larger and Internet-scale deployments, scalability is a concern and
   further study is needed.

8.  Acknowledgments

   This work is partly funded by the ANR LISP-Lab project #ANR-
   13-INFR-009 (https://lisplab.lip6.fr).

9.  IANA Considerations

   This document makes no request to IANA.

10.  Normative References

   [I-D.ietf-lisp-rfc6833bis]
              Fuller, V., Farinacci, D., and A. Cabellos-Aparicio,
              "Locator/ID Separation Protocol (LISP) Control-Plane",
              draft-ietf-lisp-rfc6833bis-10 (work in progress), March
              2018.

   [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>.

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

Authors' Addresses

   Alberto Rodriguez-Natal
   Cisco Systems
   170 Tasman Drive
   San Jose, CA
   USA

   Email: natal@cisco.com






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   Vina Ermagan
   Cisco Systems
   170 Tasman Drive
   San Jose, CA
   USA

   Email: vermagan@cisco.com


   Johnson Leong
   Cisco Systems
   170 Tasman Drive
   San Jose, CA
   USA

   Email: joleong@cisco.com


   Fabio Maino
   Cisco Systems
   170 Tasman Drive
   San Jose, CA
   USA

   Email: fmaino@cisco.com


   Albert Cabellos-Aparicio
   Technical University of Catalonia
   Barcelona
   Spain

   Email: acabello@ac.upc.edu


   Sharon Barkai
   Fermi Serverless
   CA
   USA

   Email: sharon@fermicloud.io










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   Dino Farinacci
   lispers.net
   San Jose, CA
   USA

   Email: farinacci@gmail.com


   Mohamed Boucadair
   Orange
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com


   Christian Jacquenet
   Orange
   Rennes  35000
   France

   Email: christian.jacquenet@orange.com


   Stefano Secci
   LIP6 UPMC
   France

   Email: stefano.secci@lip6.fr






















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