Hey Ian!
If you only want to influence your "outbound" traffic, you can use the local-preference and weights...
the steps for route selection are:
1. weight
2. Local preference
3. path originating on same router
4. shorter AS path
5. Lowest origin code (IGP/EGP/Incomplete)
6. lowest MED
7. External path over Internal path
8 Closest IGP neighbor
9. Path with lowest BGP router ID
So yes you have pretty much summarized the route selection, for OUTBOUND traffic. Of course you do apply these with route-maps and AS paths...to influence your inbound paths, you need to prepend your AS paths, AND work
with your providers...
I would also suggest to read the Halibi book as it goes into detail about may of these topics. You may also want to grab the RFC's...
Everett
I Stong wrote:
> Just a quick followup regarding my earlier post.
>
> To influence OUTBOUND traffic to the internet to take one router over another (regardless of which router the traffic came in) I would tweak BGP preferences such as local pref, metric, etc using route maps and such.
>
> Is that a fair summarization and grasp of the concept?
>
> -----Original Message-----
> From: Steve Meuse
> Sent: Fri, 01 Oct 1999 01:15:40 -0400
> To: doleary@juniper.net, routerman@briefcase.com, cisco-nsp@iagnet.net
> Subject: Re: [nsp] BGP routing questions
>
> At 09:06 PM 09/30/1999 -0700, dave o'leary wrote:
>
> >there are various options available to you, but some involve getting
> >the folks on the other end to change their router configs. Keep in mind
> >that traffic is bidirectional, and the techniques that you use can affect
> >what traffic is sent *to* you over a given link but not necessarily how
> >you send your traffic out, and vice versa.
>
> Also, some providers allow you to tweak your announcements to them by
> setting BGP communities. We do this by allowing customers to set their
> local_pref to one of 3 values (customer preference, peer preference, below
> peer preference). Of course, this only helps if you have multiple prefixes
> to announce, which may or may not be the case. Some providers also will
> have standard routing services like the ability to send only that providers
> customer prefixes. Asking your provider what services they offer is
> probably a good start.
>
> -Steve
>
> P.S. See everyone in Montreal!!!
>
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--
<><><><><><><><><><><><><><><><><><><><><><><><><><><>
"Failure is not an option"
Gene Cranz, Apollo 13 mission
<><><><><><><><><><><><><><><><><><><><><><><><><><><>
Everett Dowd edowd@clark.net
CCIE #2409 http://www.clark.net/pub/edowd
Just bein' virtual =8^) Welcome to the 'net
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