From: Chua, Parry (Parry.Chua@xxxxxxxxxx)
Date: Sun Feb 17 2002 - 00:41:21 GMT-3
Hi,
once 172.16.1.0 is redistributed into one end of As 100, now it will
become the internal
route of as 100 which will adverise to R4. R4 learn 172.16.1.0 from AS
[500 600] and now also from as [100]. So as 100 is the shortest path.
Regards
Parry
-----Original Message-----
From: tang bing [mailto:tang_bing@yahoo.com]
Sent: Saturday, February 16, 2002 12:22 PM
To: michael robertson; ccielab@groupstudy.com
Subject: Re: seems that nobody can solve this BGP problem?????
If the problem is like what you said ,why don't you
change the routes from r4 to higher weight ?
--- michael robertson <michael_w_2ca@yahoo.ca> wrote:
> Hi, Group,
>
> can anyone out there help me to solve the following
> problem. the scenario is as follows:
> R4 is in As 400, R5 is in AS 500, R1 R2 and R3 are
> all
> in the same AS 100. among R1 R2 R3, it's running
> isis
> or rip ( any IGP).there is no IBGP connection
> between
> R1 and R3. R6, R7 is in AS 600. amont R4, R5, R6,
> they
> are running ebgp. R4 and R1, R5 and R3 is running
> EBGP.
> R1 and R3 are redistribution point where there are
> mutual ridistribution between ISIS and bgp.
>
> Then the problem happens.network 172.16.1.0 can be
> learn by R4 with best next hop R1. and R1 has route
> to 172.16.1.0 with best next hop as his own
> connected
> interface to R2.
> I guess the reason is that when R1 and R3 learn the
> route from R4 and R5 from ebgp, then it's
> redistributed to isis, then redistributed back to
> ebgp.
> i.e. 172.16.1.0 can propagate to R6--R5--R3 by ebgp,
> then in R3, it's redistributed into ISIS and
> propagate
> to R2-R1 by ISIS. then in R1, it's redistributed to
> BGP, here, in R1, R1 consider that it's locally got
> the route, thus he give the route 172.16.1.0 a
> weight
> 32768 which has preference over the route learn from
> R4.
>
> That's explain the reason why it got the route like
> that. Am i right? or how Can i solve the problem?
>
> as always, any help will be greatly appreciated
>
> Regards
>
> michael
>
> *****************************************
> network 172.16.1.0
> R7----R6
> |
> |
> R4-------|--------R5
> | |
> | |
> | |
> R1------R2--------R3
>
> 192.168.1.0
> ******************************************
>
>
>
>
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