From: Jobson, Eddie (EJobson@xxxxxxxxxxxxx)
Date: Thu Nov 15 2001 - 10:12:20 GMT-3
I'm going to give that a try when I get a chance. I think that may explain
the locally preferred routes but I'm not sure if it will allow the EBGPpeer
to pick up both sets? We'll see. I'll get back to you.
Thanks guys.
-----Original Message-----
From: Jing.Zeng@peakxv.net
To: Charles Manafa
Cc: ccielab@groupstudy.com; Curtis Call; Jobson Eddie
Sent: 14/11/01 19:15
Subject: Re: [MED problem]
the route reflector will only reflect the best route to the IBGP peers.
So rtr B will only get one route about TKR1 (low MED one) from rtr C
also
the same rtr A get one route about TKR2 ( lower MED one)
If you change the IBGP to fully meshed from route reflector, the rtr A
and
rtr B should get two routes.
Jing Zeng
"Charles Manafa"
<charles.manafa@blueyon To: "Curtis Call"
<curtiscall@usa.net>, <ccielab@groupstudy.com>,
der.co.uk> "Jobson Eddie"
<EJobson@thrupoint.net>
Sent by: cc:
nobody@groupstudy.com Subject: Re: [MED
problem]
11/14/2001 02:13 PM
Please respond to
"Charles Manafa"
I think you will find that "maximum-paths" BGP router config, will allow
BGP
to use up to 6 equal paths to the destination.
----- Original Message -----
From: "Curtis Call" <curtiscall@usa.net>
To: <ccielab@groupstudy.com>; "Jobson Eddie" <EJobson@thrupoint.net>
Sent: Wednesday, November 14, 2001 3:44 PM
Subject: Re: [MED problem]
> BGP just selects one route, you won't see two BGP routes to the same
> destination in your routing table. (At least you shouldn't)
>
> "Jobson, Eddie" <EJobson@thrupoint.net> wrote:
> > I am having problems getting both routes to an external BGP neighbor
when
> > setting different metrics. Can anyone tell me what I'm missing. The
only
> > thing I haven't tried yet is the deterministic commands.
> >
> > Diagram
> >
> > ------------
> > | Ext. |
> > | BGP peer |
> > -------------
> > | |
> > | |
> > | |
> > --------- ---------
> > | Rtr A | | Rtr B |
> > TKR1---------| | | |-------TKR2
> > ---------- ----------
> > | |
> > WAN 0 | | WAN 1
> > | |
> > --------
> > | Rtr C |
> > | RR |
> > ---------
> >
> > The EBGPpeer is peering with both Rtr A & Rtr B but want it to
prefer
TKR1
> > on RtrA and TKR2 on RtrB, unless either of the links fail. If so and
the
> Rtr
> > B to EBGP peer fails use the Router reflector RtrC to get to TKR2
and
vice
> > versa.
> >
> >
> > I've tried various enabling of next hop self, redistribute
connected,
> > network staements all in different combinations but no luck. I get
TKR1
> > showing up as a metric of 50 when all links are up and TKR2 as a
metric
of
> > 50, but I would have expected a less preferred route with a metric
of
60
> > also shown without the > sign in the show ip bgp table. If I pull
one
of
> the
> > links I loose the route, but I have full connectivity between
RtrA-RR-RtrB
> > over IBGP/IGP.
> >
> > Configs
> > RtrA
> > router bgp 1
> > neighbor EBGPpeer remote-as 100
> > neighbor EBGPpeer upd lo0
> > neighbor EBGPpeer route-map med out
> > neighbor EBGPpeer ebgp-multihop 5 (there is another router in the
way
not
> > shown on the diag)
> > network TKR1 mask 255.255.255.0
> > network TKR2 mask 255.255.255.252
> > neighbor RtrC remote-as 1
> > neighbor RtrC upd lo0
> > neighbor RtrC next-hop-self
> > no sync
> > route-map med permit 10
> > match ip add 1
> > set metric 50
> > route-map med permit 20
> > match ip add 2
> > set metric 60
> > route-map med permit 30
> > access-list 1 permit TKR1
> > access-list 2 permit TKR2
> >
> > RtrB
> > router bgp 1
> > neighbor EBGPpeer remote-as 100
> > neighbor EBGPpeer upd lo0
> > neighbor EBGPpeer route-map med out
> > network TKR1 mask 255.255.255.0
> > network TKR2 mask 255.255.255.252
> > neighbor RtrC remote-as 1
> > neighbor RtrC upd lo0
> > neighbor RtrC next-hop-self
> > no sync
> > route-map med permit 10
> > match ip add 1
> > set metric 50
> > route-map med permit 20
> > match ip add 2
> > set metric 60
> > route-map med permit 30
> > access-list 1 permit TKR2
> > access-list 2 permit TKR1
> >
> > RtrC
> >
> > router bgp 1
> > neighbor RtrA remote-as 1
> > neighbor RtrA upd lo0
> > neighbor RtrA route-reflector-client
> > neighbor RtrB remote-as 1
> > neighbor RtrB upd lo0
> > neighbor RtrB route-reflector-client
> > no sync
> >
> > EBGPpeer
> > router bgp 100
> > neighbor RtrA remote-as 1
> > neighbor RtrA ebgp-multihop 5 (hidden router)
> > neighbor RtrB remote-as 1
> >
> > That's it! As I say full IP connectivity and routes being received
when
all
> > links are up, but less preffered metric 60 routes do not appear?
> >
> > Any help appreciated,
> >
> > Eddie.
>
>
>
> ----------
> curtiscall@usa.net
> OSPF/BGP Practice Exams
> www.boson.com\tests\Advanced.htm
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