North American Network Operators Group

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Re: Prefix filtering for Cisco SUP2

  • From: Andy Dills
  • Date: Fri Feb 29 14:14:10 2008

On Fri, 29 Feb 2008, Henry Futzenburger wrote:

> 2. Accept only default and RIR minimum routes from upstream.
>     a. Filter based on RIR minimums, rely on default for unaggregated
> routes.
>     b. Assume a reduction of about 50,000-100,000 total routes.
> Does anyone have any opinions as to whether one option is better than the
> other?  Are there options that would be better than either of these?  Are
> there serious risks to either option?
> My sense is that either of these would be a fairly benign change, only
> having a marginal impact on routing efficiency in either case.  It seems
> like the better option is the one that retains the greater number of routes
> within some margin of safety.  What do you think?

I chose number 2. 

It works so well I'm starting to wonder why any network with less than, 
say, three or four transit providers would want to do anything else, even 
without system limits. 

My philosophy is rapidly becoming "Let the settlement-free club worry 
about all the deaggregated prefixes."


Andy Dills
Xecunet, Inc.