From: OzgurG@garanti.com.tr
Date: Sat Feb 21 2004 - 15:33:32 GMT-3
on R1 you should inject 192.168.0.0/24 and filter the rest to R2.
Ozgur
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Michael Snyder
Sent: Saturday, February 21, 2004 8:29 PM
To: ccielab@groupstudy.com
Cc: 'Alec'
Subject: RE: BGP aggregate quiz
The prefix list goes on the incoming/outgoing bgp neighbor command.
The sample I gave is the `standard don't advertise the aggregate back
the way the specific routes came in`. Instead advertise one specific
route to one router, and the aggregate summary from to another, or/and
advertise two specific routes to another` All which can be done thru
outgoing prefix lists.
Re-reading your question, I have given you the wrong answer.
Anything without a slash value in the bgp table is classful.
So 192.68.0.0 is 192.168.0.0/24 which you can't get aggregating
192.168.1.0/24 or 192.168.2.0/24. I could do a 192.68.0.0/23 pretty
easy.
I don't know the answer if that's all you have to work with.
-----Original Message-----
From: Alec [mailto:clapun@graduate.hku.hk]
Sent: Saturday, February 21, 2004 12:17 PM
To: Michael Snyder; ccielab@groupstudy.com
Subject: Re: BGP aggregate quiz
Michael,
Could u explain why prefix list can be solved ? BTW, where does the
prefix-list apply ? Still can't think of how does it relate to building
the
BGP entry in R2.
----- Original Message -----
From: "Michael Snyder" <msnyder@revolutioncomputer.com>
To: <ccielab@groupstudy.com>
Cc: "'Alec'" <clapun@graduate.hku.hk>
Sent: Sunday, February 22, 2004 2:10 AM
Subject: RE: BGP aggregate quiz
> Prefix lists
>
> Something like this.
>
>
> ip prefix-list one seq 5 deny 192.68.0.0/16
> ip prefix-list one seq 10 permit 0.0.0.0/0 le 32
>
> ip prefix-list two seq 5 deny 192.68.0.0/16 ge 24 le 24
> ip prefix-list two seq 10 permit 0.0.0.0/0 le 32
>
> -----Original Message-----
> From: Alec [mailto:clapun@graduate.hku.hk]
> Sent: Saturday, February 21, 2004 12:03 PM
> To: ccielab@groupstudy.com
> Subject: BGP aggregate quiz
>
> Hi group,
>
> Really stuck by this BGP quiz. Anyone can shed some light ? Assuming
> two
> prefixes 192.68.1.0/24 and 192.68.2.0/24 are coming from the AS and R1
> is
> doing an aggregate. The trickiest part is how to make build an entry
> 192.68.0.0 on R2's BGP table (note that there is no slash subnet
mask!!)
>
> AS ----- R1 ------ R2
>
> R1 BGP Table after aggregate
> *> 192.68.0.0/16
> *> 192.68.1.0
> *> 192.68.2.0
>
> R2 BGP Table which is goal to this senario.
> *> 192.68.0.0
>
> R1'router must advertise by 192.68.0.0 except /16'mark
> Don't see "/16" word in R2 and it must see "192.68.0.0" only.
> Don't see "S" suppress mark in R1.
> Don't use summary-only command by R1.
>
>
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