From: Sila Moni (silamoni@yahoo.com)
Date: Wed Jun 29 2005 - 08:38:46 GMT-3
There are several options that you can play with
according to bgp decision order process:
Weight (highest)
Local-Preference (highest)
Locally Originated
AS-Path (shortest)
Origin (IGP > EGP > ?)
MED (lowest - 0 by default)
-Weight and Local-Preference apply inbound to affect
outbound traffic
-AS-Path and MED apply outbound to affect inbound
traffic
Since AS-Path is not allowed, you have can set:
- MED high toward R8 and low toward BB1; (did you
clear the bgp process?)
- Locally on BB2, you can use weight or LP; you can
also change the origin using route-map (IGP > EGP >
?); incomplete is less preferred.
--- k c <jwongccie@yahoo.com.hk> wrote:
> Hi Group,
>
> BB1 (AS500) --- R1 (AS100)
> | |
> | R2 (AS200)
> | |
> BB2 (AS500) --- R8 (AS300)
>
> R1 and R8 announce 2.2.2.0/24 to BB1 & BB2. Without
> modifying any attributes, BB1 will choose R1 and BB2
> will choose R8 as next hop. The task is to make sure
> BB2 will reach 2.2.2.0/24 via BB1. AS prepend method
> is not allowed. When I use metric, it doesn't work?
> BB2 still choose R8. How can I influence bb2 to
> choose R8? How many methods (beside AS prepend) can
> I use?
>
> bb2-7206g1>sh ip bgp
> BGP table version is 23, local router ID is
> 208.10.90.1
> Status codes: s suppressed, d damped, h history, *
> valid, > best, i - internal,
> r RIB-failure, S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
> Network Next Hop Metric
> LocPrf Weight Path
> *> 2.2.2.0/24 192.168.80.8 5
> 0 300 200 ?
> * i 192.168.10.1 0
> 100 0 100 200 ?
> *> 5.5.5.0/24 192.168.80.8
> 0 300 200 ?
> * i 192.168.10.1 0
> 100 0 100 200 ?
> bb2-7206g1>sh ip bgp 2.2.2.0
> BGP routing table entry for 2.2.2.0/24, version 23
> Paths: (2 available, best #1, table
> Default-IP-Routing-Table)
> Advertised to update-groups:
> 2
> 300 200
> 192.168.80.8 from 192.168.80.8 (136.10.8.8)
> Origin incomplete, metric 5, localpref 100,
> valid, external, best
> 100 200
> 192.168.10.1 (metric 5) from 12.12.12.1
> (100.10.15.1)
> Origin incomplete, metric 0, localpref 100,
> valid, internal
> bb2-7206g1>
>
> 8. If the origin codes are the same, prefer the
> route with the lowest MED metric attribute.
> 9. Prefer the external BGP (eBGP) path over the iBGP
> path.
>
> Thanks.
>
> &3'Y.I3q*>!A&,_'
>
>
This archive was generated by hypermail 2.1.4 : Wed Jul 06 2005 - 14:43:45 GMT-3