Internet DRAFT - draft-templin-intarea-rio-redirect
draft-templin-intarea-rio-redirect
Network Working Group F. Templin, Ed.
Internet-Draft Boeing Research & Technology
Updates: rfc4191, rfc4861 (if approved) January 06, 2017
Intended status: Standards Track
Expires: July 10, 2017
Route Information Options in Redirect Messages
draft-templin-intarea-rio-redirect-00.txt
Abstract
The IPv6 Neighbor Discovery protocol provides a Redirect function
allowing routers to inform hosts of a better next hop on the link
toward the destination. This document specifies a backward-
compatible extension to the Redirect function to allow routers to
include forwarding information that the source can associate with the
next hop.
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 July 10, 2017.
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
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include Simplified BSD License text as described in Section 4.e of
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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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Route Information Options in Redirect Messages . . . . . . . 3
3.1. Validation of Redirect Messages . . . . . . . . . . . . . 3
3.2. Router Specification . . . . . . . . . . . . . . . . . . 3
3.3. Host Specification . . . . . . . . . . . . . . . . . . . 4
4. Implementation Status . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The IPv6 Neighbor Discovery (ND) protocol [RFC2460][RFC4861] provides
a Redirect function allowing routers to inform hosts of a better next
hop on the link toward the destination. The Redirect message
includes a target address identifying the next hop and a destination
address taken from the IPv6 packet that triggered the Redirect.
"Default Router Preferences and More-Specific Routes" [RFC4191]
specifies a Route Information Option (RIO) that routers can include
in Router Advertisement (RA) messages to inform recipients of more-
specific routes. This document specifies a backward-compatible
extension to allow routers to include RIOs in Redirect messages.
This method has precedence in a published experimental RFC [RFC6706].
2. Terminology
The terminology in the normative references applies.
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]. Lower case
uses of these words are not to be interpreted as carrying RFC2119
significance.
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3. Route Information Options in Redirect Messages
The RIO is specified for inclusion in RA messages in Section 2.3 of
[RFC4191]. The IPv6 ND Redirect function is specified in Section 8
of [RFC4861], where the introductory paragraphs include the
following:
"Redirect messages are sent by routers to redirect a host to a
better first-hop router for a specific destination or to inform
hosts that a destination is in fact a neighbor (i.e., on-link)."
This specification permits routers to include RIO options in Redirect
messages so that hosts can direct future packets to a better first-
hop for a *set of destinations* instead of just a singleton. This
specification therefore updates [RFC4191] and [RFC4861] as discussed
in the following sections.
3.1. Validation of Redirect Messages
The validation of Redirect messages follows Section 8.1 of [RFC4861]
which states:
"The contents of the Reserved field, and of any unrecognized
options, MUST be ignored. Future, backward-compatible changes to
the protocol may specify the contents of the Reserved field or add
new options; "
This specification permits routers to include RIOs in Redirect
messages, and therefore represents a backward-compatible change to
the protocol through the addition of a new option as described in
this passage.
3.2. Router Specification
The Router Specification follows Section 8.2 of [RFC4861], except
that RIOs are included in the list of permissible options. Routers
therefore MAY send Redirect messages containing RIOs, where the RIOs
are determined by a means outside the scope of this specification.
When the router includes RIOs, it MAY set the Destination Address
field of the Redirect message to '::' (i.e., the IPv6 unspecified
address) if the destination of the packet that triggered the
redirection event is covered by a prefix in one of the RIOs.
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3.3. Host Specification
The Host Specification follows Section 8.3 of [RFC4861] and Section 3
of [RFC4191]. According to [RFC4861], a host receiving a valid
Redirect updates its destination cache and neighbor cache per the
Destination and Target information included in the message,
respectively. According to [RFC4191], a "Type C" host receiving a
valid RA message updates its routing table per the RIOs included in
the message.
In light of these considerations, a "Type C" host that receives a
Redirect message containing RIOs adopts the combined behaviors of
both of these specifications. Namely, the host updates its neighbor
cache entry for the Target and updates its routing table per the
included RIOs. If the Destination address is not the unspecified
address, the host further updates its destination cache.
Note that "Type A'" and "Type B" hosts ignore any RIOs and process
the Redirect message according to Section 8.3 of [RFC4861].
4. Implementation Status
The Redirect function and RIOs are widely deployed in IPv6
implementations.
5. IANA Considerations
This document introduces no IANA considerations.
6. Security Considerations
Security considerations for Redirect messages that include RIOs are
the same as for any IPv6 ND messages as specified in Section 11 of
[RFC4861]. Namely, the protocol must take measures to secure IPv6 ND
messages on links where spoofing attacks are possible.
A spoofed Redirect message containing no RIOs could cause corruption
in the host's destination cache while a spoofed Redirect message
containing RIOs could corrupt the host's routing tables. While the
latter would seem to be a more onerous result, the possibility for
corruption is unacceptable in either case.
7. Acknowledgements
This document was motivated by discussions on the intarea list.
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8. References
8.1. Normative References
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<http://www.rfc-editor.org/info/rfc791>.
[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>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC4191] Draves, R. and D. Thaler, "Default Router Preferences and
More-Specific Routes", RFC 4191, DOI 10.17487/RFC4191,
November 2005, <http://www.rfc-editor.org/info/rfc4191>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
8.2. Informative References
[RFC6706] Templin, F., Ed., "Asymmetric Extended Route Optimization
(AERO)", RFC 6706, DOI 10.17487/RFC6706, August 2012,
<http://www.rfc-editor.org/info/rfc6706>.
Author's Address
Fred L. Templin (editor)
Boeing Research & Technology
P.O. Box 3707
Seattle, WA 98124
USA
Email: fltemplin@acm.org
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