Publish-Subscribe mechanism for LISP
draft-rodrigueznatal-lisp-pubsub-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Alberto Rodriguez-Natal , Vina Ermagan , Johnson Leong , Fabio Maino , Albert Cabellos-Aparicio , Sharon Barkai , Dino Farinacci | ||
| Last updated | 2017-08-02 | ||
| Replaced by | draft-ietf-lisp-pubsub, draft-ietf-lisp-pubsub, RFC 9437 | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-rodrigueznatal-lisp-pubsub-00
LISP Working Group A. Rodriguez-Natal
Internet-Draft V. Ermagan
Intended status: Experimental J. Leong
Expires: February 3, 2018 F. Maino
Cisco Systems
A. Cabellos-Aparicio
Technical University of Catalonia
S. Barkai
Fermi Serverless
D. Farinacci
lispers.net
August 2, 2017
Publish-Subscribe mechanism for LISP
draft-rodrigueznatal-lisp-pubsub-00
Abstract
This document describes simple extensions 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.
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This Internet-Draft will expire on February 3, 2018.
Copyright Notice
Copyright (c) 2017 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
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publication of this document. Please review these documents
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carefully, as they describe your rights and restrictions with respect
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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 . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
10. Normative References . . . . . . . . . . . . . . . . . . . . 7
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 a Mapping System (basically a distributed database)
that stores and disseminates EID-RLOC mappings and on LISP tunnel
routers (xTRs) that encapsulate and decapsulate packets based on
those mappings.
ITRs/RTRs/PITRs pull EID-to-RLOC mapping information from the Mapping
System by means of explicitly requesting mappings. [RFC6830]
indicates how ETRs can tell ITRs/RTRs/PITRs about mapping changes.
This document presents a Publish/Subscribe (PubSub) architecture 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.
In general, when an ITR/RTR/PITR wants to be notified for mapping
changes, the following flow occurs:
(1) The ITR/RTR/PITR sends a Map-Request for the EID-prefix.
(2) The ITR/RTR/PITR sets the subscribe bit on the Map-Request and
includes its xTR-ID.
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(3) The Map-Request flows 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.
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 send
Map-Replies 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.
The distribution of xTR-IDs and the management of security
associations are out of the scope of this document.
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4. Map-Request Additions
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|X| 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 ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ |S| Reserved | EID mask-len | EID-Prefix-AFI |
Rec +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | EID-Prefix ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Map-Reply Record ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ +
| |
+ xTR-ID +
| |
+ +
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Map-Request with S bit and xTR-ID
The following fields are added to the Map-Request message defined in
[RFC6830].
xTR-ID bit (X-bit): the first bit after the s bit in the Map-
Request header. The X-bit of a Map-Request message is set to
specify that 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).
xTR-ID field: 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.
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The following field is added to the EID-Record field of a Map-Request
message defined in [RFC6830]:
Subscribe bit (S-bit): the first bit in the EID-Record section of
a Map-Request message. The S-bit of an EID-record is set to 1 to
specify that the xTR wants to be notified of updates for that
mapping record.
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 S-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 S-bit to 1 in each EID-Record to which the
xTR wants to subscribe.
(2) The X-bit of the Map-Request message MUST be set to 1, to
specify the presence of an xTR-ID field that uniquely identifies
the xTR.
The Map-Request is routed to the appropriate Map-Server through the
Mapping System. No 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 MUST process it as
described in [RFC6830]. After correct processing, for each EID-
Record that has the S-bit set to 1, the Map-Server MUST try to add
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 on
[RFC6830] to build the Map-Notify with the following considerations.
The Map-Server MUST use the nonce from the Map-Request as the nonce
for the Map-Notify. The Map-Server MUST use its security association
with the xTR (see Section 3) to compute the authentication data of
the Map-Notify. 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-Requests sent with a S-bit set, it knows
that the Map-Notify is to acknowledge a successful subscription. The
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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 (e.g. 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 reply to the Map-
Request with a Map-Reply 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.
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.
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(2) The nonce of the Map-Notify 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 not present in any
list of previously sent nonces, and an EID not local to the xTR, the
xTR knows that the Map-Notify has been received due to an update on
the RLOC-set of a cached mapping.
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.
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
TBD.
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-05 (work in progress), May
2017.
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[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>.
[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>.
Authors' Addresses
Alberto Rodriguez-Natal
Cisco Systems
170 Tasman Drive
San Jose, CA
USA
Email: natal@cisco.com
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
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Albert Cabellos-Aparicio
Technical University of Catalonia
Barcelona
Spain
Email: acabello@ac.upc.edu
Sharon Barkai
Fermi Serverless
CA
USA
Email: sharon@fermicloud.io
Dino Farinacci
lispers.net
San Jose, CA
USA
Email: farinacci@gmail.com
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