Re: Fundamental questions of backbone design

[Grzegorz Janoszka <Grzegorz () Janoszka pl>]

On 2013-10-18 20:03, Anurag Bhatia wrote:
>     1. As I understand it's (sort off) common practice to give highest
>     localpref to customer routes then peering and finally transit. Does this
>     works well or you see issues with people who have 10+ prepends on some
>     peering routes calling you to not send traffic via those circuits? Does it
>     makes sense to put a rule to avoid routes 2-3 AS path away when changing
>     local preference?

Hi,
You may try a different trick on peering routes. You rather don't peer 
with the tier 1 networks, so you may filter out (or assign a low 
localpref to) all prefixes received from peering partners which contain 
in as-path some well known asn's, like let's say 174, 1299, 3356 and so 
on. Such routes are most likely leaked and traffic via those paths will 
be either blackholed or, in the best case, going via not really optimal 
path.

>     2. If I have more peering capacity and relatively less capacity between
>     my own PoPs and I start injecting routes in my IGP then how to prevent
>     change of choking of backbone? Is it standard practice to have more
>     capacity on backbone then peering links? Or I have to inject less routes in
>     IGP - say a few % of total routes?

You may always prefer peering routes local to the PoP (giving them the 
highest localpref). This way you will not carry so much traffic on your 
backbone.

--
Grzegorz Janoszka