[c-nsp] Sub-second Fast Reconvergence for OSPF?

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Mon Feb 13 14:42:43 EST 2006

William Chu <> wrote on Monday, February 13, 2006 8:22 PM:

> Hi:
> Is there a feature on Cisco IOS that supported this today? If not
> OSPF, how about IS-IS? 

Both ISIS and OSPF are able to converge in << 1 sec in most
environments. This is not a single feature but rather a collection of
features and internal enhancements as well as proper design. 

> Or what combination of features would allow
> fast layer-3 reconvergence in under a second in a LAN-based
> environment? 

key for fast convergence here is fast failure detection. You likely need
BFD to support sub-second, fast-hello's are not very scalable and can
lead to false negatives..


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