NSP ... New Information

Paul Ferguson pferguso at cisco.com
Tue Jun 10 15:19:50 UTC 1997

At 09:22 AM 06/10/97 -0500, Phil Howard wrote:

>Right.  But people see it as such a problem because the routing policies
>are IP space derived.  When people are told they need a /19 to be routable,
>then they begin to go backwards on solving the IP space problem and resume
>wasting it (but hiding the waste to look like its used).

But this is somewhat of a misnomer. It is not an issue of being
'routable' v. 'non-routable', but rather, one of whether you can
be aggregated into a larger prefix. This practice encourages
aggregation -- it is commonly agreed that Aggregation is Good (tm).

The routability issue comes into play when:

 o You are specifically referring to routes being propagated by
   a service provider who uses prefix-length filters, AND

 o You cannot be aggregated into a large enough advertised CIDR
   block to conform to these types of filters.

>When the need to justify space usage occurred, along with it came some ideas
>on actually how to do that.  And I see that working.  We were projected to
>run totally out of space by now, and since we have not, I assume it did work
>pretty well.

BGP4, CIDR, or Die.

>But the real problem is routing policies that are encouraging people to go
>back to wasting space.  By using the network size as the criteria for doing
>route filtering, the smaller guys get screwed and they see their solution
>as inflating their network.  This practice needs to be stopped or a better
>solution needs to come out of it.

One might suggest that some of the prefix length filter could be
replaced by more aggressive dampening policies.

- paul

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