From: Thekkethala (thek@xxxxxxxxxxxx)
Date: Tue Nov 13 2001 - 15:21:30 GMT-3
Thanks Percy for that input ....
I did notice (later) that at the end of that section he has used a command
neighbor <> unsupress-map <> ...... which explained his configuration in a
way cause that was the only way RTRA could suppress 172.16.220.0 in general
but 'unsupress' with respect to RTR F .
It was a long night with that one and in a way I am glad I did not turn the
page till 4:00 in the morning - learnt a lot in the bargain !!
----- Original Message -----
From: "Perminder Grewal" <percy_gunner@hotmail.com>
To: <thek@mediaone.net>; <ccielab@groupstudy.com>
Sent: Tuesday, November 13, 2001 10:40 AM
Subject: Re: Clarification : BGP Aggregation
> Ajit
>
> I believe RTA is advertising network 172.16.220.0/24 via IGP (ospf),so
> destination 172.16.220/24 will be in RTF route table via next hop
> 172.16.1.1, this route is not suppressed in an ospf update, but is in a
BGP
> update as shown in BGP table for RTA. Then in RTF he has a statement under
> router bgp 3 network 172.16.220.0 mask 255.255.255.0 (origin igp) which
> syncs with IGP ie RTF route table for network 172.16.0.0/24(ospf)(even
> though he has no sync command enabled) then BGP process place's that as a
> best route in the BGP table for RTF.
>
> Note ospf is running in this set-up as he does state he has left out some
> configs too save time/space.
>
> regards
>
> Percy
>
>
> >From: "Thekkethala" <thek@mediaone.net>
> >Reply-To: "Thekkethala" <thek@mediaone.net>
> >To: <ccielab@groupstudy.com>
> >Subject: Clarification : BGP Aggregation
> >Date: Mon, 12 Nov 2001 20:30:45 -0500
> >
> >This is with respect to the configuration on Page 351-353 of Halabi's
book
> >regarding Aggregation with a subset of more specific routes.
> >
> >Not clear on how the objective is being reached ??
> >
> >The question ?
> >
> >1. RTR A is using a suppress map for 172.16.220.0 and therefore not
> >advertising out to any peer.
> >
> >So how does Router F get to know abt this subnet ?? (even though RTR F
> >config
> >has a network staement for 172.16.220.0 ... it is not relevant is it
cause
> >it
> >does not originate form there ??)
> >
> >2. Therefore how can Router F advertise this out via its EBGP when its
NOT
> >EVEN present in its BGP table on account of Router A's suppress map on
for
> >this subnet ???
> >
> >Am I missing something basic ?????/
> >
> >thanks ....still wondering hhhhmmm !!
> >
> >Ajit
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