From: k c (jwongccie@yahoo.com.hk)
Date: Wed Jun 29 2005 - 11:59:42 GMT-3
Dear All,
Thanks for your input. I think the easiest way is to anounce the route with origin igp on R1. If the BB2 is already input "bgp always-compare-med", then modify metric is easy as well.
Zouta oxpf <zouta.oxpf@gmail.com> ;!!G
To use the "bgp always-compare-med" command though, it has to be
configured on the BB routers, which might not be allowed.
A good option is changing the origin codes at AS 100 & AS 300, since
as-path prepending is not allowed.
ZO
On 6/29/05, Sila Moni wrote:
> Good point. Also, there are two other options, policy
> routing on bb2 and bgp conditional advertisement on
> R8, that one can try. Can someone lend me a rack to
> lab this out? :)
>
> --- Zouta oxpf wrote:
>
> > Did you try using the "bgp always-compare-med"
> > command?
> >
> > ZO
> >
> > On 6/29/05, k c 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&,_'
> > >
> > >
> >
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This archive was generated by hypermail 2.1.4 : Wed Jul 06 2005 - 14:43:45 GMT-3