Internet-Draft draft-ietf-lsr-distoptflood-04.txt is now available. It is a
work item of the Link State Routing (LSR) WG of the IETF.
Title: IS-IS Distributed Flooding Reduction
Authors: Russ White
Shraddha Hegde
Tony Przygienda
Luay Jalil
Name: draft-ietf-lsr-distoptflood-04.txt
Pages: 15
Dates: 2024-04-29
Abstract:
In dense topologies (such as data center fabrics based on the Clos
and butterfly though not limited to those; in fact any topology with
relatively high degree of connectivity qualifies here) IGP flooding
mechanisms designed originally for rather sparse topologies can
"overflood", or in other words generate too many identical copies of
same information arriving at a given node from other devices. This
normally results in slower convergence times and higher resource
utilization to process and discard the superfluous copies.
Distributed algorithms that restrict the amount of flooding performed
can be constructed, as long as they result in a flooding subgraph
connecting all nodes on the network in terms of flooding still. Such
algorithms can reduce resource utilization significantly, while
improving convergence performance. We denote such algorithm as
"distributed flooding prunners" (or "prunner" for short) while
requiring them to follow some simple, additional rules. The rules
presented in detail later allow to deploy mix of nodes any prunning
algorithm and multiple prunners at the same time if necessary while
ensuring correct flood coverage for the whole network. Additionally,
node by node migration, without flag day, from one algorithm to
another if necessary is possible. And assuming the algorithms are
behaving correctly, the blast radius on algorithm change is normally
contained to a single node performing the switch and obviously the
convergence of an algorithm on introduction or removal of node
running such algorithm.
One such algorithm (modification of previous art), deployable even
without configuration, is described in this document. Beside
reducing the extraneous copies, the proposed solution does "load-
balance" flooding across different possible paths in the network to
prevent build up of flooding hot-spots.
The IETF datatracker status page for this Internet-Draft is:
https://datatracker.ietf.org/doc/draft-ietf-lsr-distoptflood/
There is also an HTML version available at:
https://www.ietf.org/archive/id/draft-ietf-lsr-distoptflood-04.html
A diff from the previous version is available at:
https://author-tools.ietf.org/iddiff?url2=draft-ietf-lsr-distoptflood-04
Internet-Drafts are also available by rsync at:
rsync.ietf.org::internet-drafts
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