Neighbor Unreachability Detection is too impatient
draft-ietf-6man-impatient-nud-06
The information below is for an old version of the document |
Document |
Type |
|
Active Internet-Draft (6man WG)
|
|
Authors |
|
Igor Gashinsky
,
Erik Nordmark
|
|
Last updated |
|
2013-06-13
(latest revision 2013-04-24)
|
|
Replaces |
|
draft-nordmark-6man-impatient-nud
|
|
Stream |
|
IETF
|
|
Intended RFC status |
|
Proposed Standard
|
|
Formats |
|
pdf
htmlized (tools)
htmlized
bibtex
|
|
Reviews |
|
|
Stream |
WG state
|
|
Submitted to IESG for Publication
|
|
Document shepherd |
|
Ole Trøan
|
|
Shepherd write-up |
|
Show
(last changed 2013-02-18)
|
IESG |
IESG state |
|
Approved-announcement to be sent::Revised I-D Needed
|
|
Consensus Boilerplate |
|
Unknown
|
|
Telechat date |
|
|
|
Responsible AD |
|
Brian Haberman
|
|
IESG note |
|
Ole Troan is the document shepherd.
|
|
Send notices to |
|
6man-chairs@tools.ietf.org, draft-ietf-6man-impatient-nud@tools.ietf.org
|
IANA |
IANA review state |
|
IANA OK - No Actions Needed
|
6MAN WG E. Nordmark
Internet-Draft Cisco Systems, Inc.
Updates: 4861 (if approved) I. Gashinsky
Intended status: Standards Track Yahoo!
Expires: October 26, 2013 April 24, 2013
Neighbor Unreachability Detection is too impatient
draft-ietf-6man-impatient-nud-06.txt
Abstract
IPv6 Neighbor Discovery includes Neighbor Unreachability Detection.
That function is very useful when a host has an alternative neighbor,
for instance when there are multiple default routers, since it allows
the host to switch to the alternative neighbor in short time. This
time is 3 seconds after the node starts probing by default. However,
if there are no alternative neighbors, this is far too impatient.
This document specifies relaxed rules for Neighbor Discovery
retransmissions that allow an implementation to choose different
timeout behavior based on whether or not there are alternative
neighbors. This document updates RFC 4861.
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 October 26, 2013.
Copyright Notice
Copyright (c) 2013 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
Nordmark & Gashinsky Expires October 26, 2013 [Page 1]
Internet-Draft NUD is too impatient April 2013
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
2. Definition Of Terms . . . . . . . . . . . . . . . . . . . . . . 4
3. Protocol Updates . . . . . . . . . . . . . . . . . . . . . . . 4
4. Example Algorithm . . . . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
Nordmark & Gashinsky Expires October 26, 2013 [Page 2]
Internet-Draft NUD is too impatient April 2013
1. Introduction
IPv6 Neighbor Discovery [RFC4861] includes Neighbor Unreachability
Detection (NUD), which detects when a neighbor is no longer
reachable. The timeouts specified for NUD are very short (by default
three transmissions spaced one second apart). These short can be
appropriate when there are alternative neighbors to which the packets
can be sent. For example, if a host has multiple default routers in
its Default Router List, or if the host has a Neighbor Cache Entry
(NCE) created by a Redirect message. In these cases, when NUD fails,
the host will try the alternative neighbor; the next router in the
Default Router List, or discard the NCE which will also send using a
different router.
The timeouts specified in [RFC4861] were chosen to be short in order
to optimize for the scenarios where alternative neighbors are
available.
However, when there is no alternative neighbor there are several
benefits in making NUD try probing for a longer time. One of those
benefits is to make NUD more robust against transient failures, such
as spanning tree reconvergence and other layer 2 issues that can take
many seconds to resolve. Marking the NCE as unreachable in that case
causes additional multicast on the network. Assuming there are IP
Show full document text