[c-nsp] Conditional BGP

[David Coulson]

Paul,

They would need to do two things.

1) AS prepend on the routes they advertise to you, so the AS path is 
longer than their path through Cogent. This will force most of their 
inbound traffic via Cogent.

2) Local pref setting for routes received from you to make them less 
desirable than the routes from Cogent. The default is 100, so they could 
set your routes to 90 or something.

Both of these are set using a route-map on their side. I'm assuming that 
there isn't anything they would want to prefer to route through you 
(your peers/customers - Or if Level3 or someone de-peers Cogent again), 
but that can be tweaked with route-maps and prefix-list filters.

David

Paul Stewart wrote:
> Hi folks..
>
>  
>
> We have a couple of customers that are looking to purchase an Internet
> connection from us - this will be a BGP feed to each customer as they are
> multihomed today etc.
>
>  
>
> Normally, we would just supply a full table and let them decide what to do
> with it.  In this scenario, they both wish to use us as a backup provider
> and wish to ONLY use our network if their primary provider (Cogent) is down.
>
>  
>
> What is common practice for this scenario?  We would still prefer to just
> send a full table and put the control into their hands but I'm also
> concerned if they will have the technical expertise to accomplish this..  On
> their side, what would be common practice?  I've been looking at conditional
> BGP advertisements using route-maps but don't believe that's the best
> solution..
>
>  
>
> Thanks for your input.
>
>  
>
> Paul
>
>  
>
>  
>
>  
>
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