North American Network Operators Group

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Re: Optical Crossconnects and IP

  • From: Vijay Gill
  • Date: Sun May 14 18:46:40 2000

On Sun, 14 May 2000, Danny McPherson wrote:

> If it were actually implemented it wouldn't be something you'd 
> hand to the NOC .. unless I'm missing something.  You don't hand 
> them your SPF algorithm, or your BGP decision algorithm .. it's 

Good point.  I assume you would calculate and precompute offline and have
the results loaded into the router.  Some implementations already use
something like this in case of fast online restoral. (Fore is one if I
remember correctly. They calculate 4 next best paths in case of failure of
the primary).

> The benefit of a circuit-based restoration mechanism (i.e. MPLS 
> fast reroute with a pre-defined backup LSP) is that when you switch 
> to a backup connection you know (with some level of confidence) that 
> packets forwarded on the connection will not be tossed around like
> hot potatos until the entire IGP converges, SPF calculation throttles
> are reset, etc.., introducing instability in the network.

Understand what you were saying now.