[nsp] BGP Best Path Selection Algorithm

[Ryan O'Connell]

Tuc wrote:

>	According to :
>
>		http://www.cisco.com/warp/public/459/25.shtml
>
>	The weight is first, local pref is second. But I'm not sure
>how it handles :
>
[snip]

>	Is it using the one with the /17 because its more specific, 
>correct? But where does it say it takes that into account? It seems like
>it talks about it per entry, but not between entries. 
>  
>

As far as BGP is concerned, they are seperate entries. Both will be 
entered both into the BGP table and the routing table on the router.[1]

However, when the router itself comes to switch packets, it will always 
take the most specific entry it can find in the routing table. (This is 
the only way to override a connected route, so it's a useful trick at 
times when you're having to hack your way round a problem you shouldn't 
have)

[1] AFAIK, anyway. I doubt a router prunes, say, a /24 just because both 
/25s are under it but I suppose one could.

-- 
         Ryan O'Connell - CCIE #8174
<ryan at complicity.co.uk> - http://www.complicity.co.uk

I'm not losing my mind, no I'm not changing my lines,
I'm just learning new things with the passage of time