IS-IS Operational Enhancements for Network Maintenance Events
draft-ietf-isis-oper-enhance-02
IS-IS Working Group N. Shen
Internet-Draft T. Li
Intended status: Informational Cisco Systems, Inc.
Expires: July 18, 2013 S. Amante
Level 3 Communications
M. Abrahamsson
Tele2
January 14, 2013
IS-IS Operational Enhancements for Network Maintenance Events
draft-ietf-isis-oper-enhance-02
Abstract
This document describes an improved IS-IS neighbor management scheme
which can be used to enhance operational experience in terms of
convergence speed and finer control of neighbor cost over a LAN.
Status of this Memo
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This Internet-Draft will expire on July 18, 2013.
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Copyright (c) 2013 IETF Trust and the persons identified as the
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Internet-Draft IS-IS Operational Enhancements January 2013
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Interface Shutdown Black Hole . . . . . . . . . . . . . . . 3
1.2. LAN of Last Resort . . . . . . . . . . . . . . . . . . . . 3
1.3. Specification of Requirements . . . . . . . . . . . . . . . 3
2. Sending Hellos with Fast Exit Notification . . . . . . . . . . 3
3. Pseudonodes with Non-zero Metrics . . . . . . . . . . . . . . . 4
3.1. Operational Considerations . . . . . . . . . . . . . . . . 5
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
6. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6
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Internet-Draft IS-IS Operational Enhancements January 2013
1. Introduction
The IS-IS [ISO 10589] routing protocol has been widely used in
Internet Service Provider IP/MPLS networks. Operational experience
with the protocol, combined with ever increasing requirements for
lossless operations have demonstrated some operational issues. This
document describes those issues and some mechanisms for dealing with
those issues. These mechanisms do involve implementation support,
but do not require protocol changes.
1.1. Interface Shutdown Black Hole
One of these operationally problematic issues occurs when IS-IS is
disabled on only one side of a link. This can result in a
significant delay before neighbor(s) on the other end of the same
link notice this change. In turn, this can result in several seconds
during which traffic is blackholed, until the IS-IS neighbor(s) time
out the adjacency and IS-IS reconverges.
1.2. LAN of Last Resort
Another issue stems from a situation when operators want to
temporarily make an interface a "last resort" link for transit
traffic. This is a straightforward, though cumbersome, operation to
perform on a point-to-point link. Each device on the link is
reconfigured to use very high metric. This causes traffic to divert
to other links in the network. This same operation is more difficult
on a multi-access LAN. There, the operator would have to increase
the metric on each and every interface attached to the LAN, requiring
the reconfiguration of a number of systems.
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