From: Cameron, John (johcamer@cisco.com)
Date: Tue Feb 18 2003 - 16:36:33 GMT-3
Actually Joe Martin raised a good point to me a bit ago - so
I labed this up as follows:
r3-----r1-----r2
r3: AS10
r1: AS30
r2: AS20
r3 peers only with r1
r1 peers with r3 and r2
r2 peers only with r3
If I configure a loopback on r3 with the address 150.50.31.1/24 and add it
to by BGP process it advertises as expected:
r3#sib
BGP table version is 70, local router ID is 204.100.100.33
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.31.0/24 0.0.0.0 0 32768 i
r1#sib
BGP table version is 15, local router ID is 204.100.100.1
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.31.0/24 204.100.100.2 0 0 10 i
r2#sib
BGP table version is 40, local router ID is 204.100.100.177
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.31.0/24 150.10.20.1 0 20 10 i
Next I added "aggregate-address 150.50.31.0 255.255.255.0 summary-only" to
r1 BGP process and recieved the same output as before:
router bgp 20
bgp log-neighbor-changes
aggregate-address 150.50.31.0 255.255.255.0 summary-only
neighbor 150.10.20.2 remote-as 30
neighbor 204.100.100.2 remote-as 10
r3#sib
BGP table version is 81, local router ID is 204.100.100.33
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.31.0/24 0.0.0.0 0 32768 i
r1#sib
BGP table version is 16, local router ID is 204.100.100.1
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.31.0/24 204.100.100.2 0 0 10 i
r2#sib
BGP table version is 46, local router ID is 204.100.100.177
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.31.0/24 150.10.20.1 0 20 10 i
The only way I could get this to work is if I shortened the mask to /16 -
which
doesn't meet the requirments.
on r1
router bgp 20
bgp log-neighbor-changes
aggregate-address 150.50.0.0 255.255.0.0 summary-only
neighbor 150.10.20.2 remote-as 30
neighbor 204.100.100.2 remote-as 10
r1#sib
BGP table version is 18, local router ID is 204.100.100.1
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.0.0 0.0.0.0 32768 i
s> 150.50.31.0/24 204.100.100.2 0 0 10 i
r2#sib
BGP table version is 48, local router ID is 204.100.100.177
Status codes: s suppressed, d damped, h history, * valid, > best, i -
internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.50.0.0 150.10.20.1 0 20 i
So I retract what I said before ;-(
Sorry for the confusion
JDC
-----Original Message-----
From: Peter van Oene [mailto:pvo@usermail.com]
Sent: Tuesday, February 18, 2003 12:54 PM
To: ccielab@groupstudy.com
Subject: RE: GBP Question
At 09:22 AM 2/18/2003 -0500, Cameron, John wrote:
>Use the following on Router B:
>
>aggregate-address 150.50.31.0 255.255.255.0 summary-only
For what its worth, this is an entirely different route than the original
path. Why not just filter the incoming route and announce your own if we
are taking that much liberty? Of note, I'm not entirely sure that the
aggregate-address command will accept a prefix of the same depth for a
contributor. Indeed, if it did, this would seem broken to me.
>This will remove Router A as the originator of the prefix
>an make it "look" as if Router C ownes the prefix.
This will create two routes in the network where one previously
existed. In my books, this wouldn't be a valid answer to the question,
then again I expect I wouldn't ask for BGP to be broken in the question.
Pete
>HTH,
>JDC
>
>
>-----Original Message-----
>From: love cisco [mailto:love_cisco@hotmail.com]
>Sent: Tuesday, February 18, 2003 5:07 AM
>To: ccielab@groupstudy.com
>Subject: GBP Question
>
>
>I have a question about filtering BGP As number in AS path table.
>
>Router A has a ip address 150.50.31.1/24 distributed in bgp AS100. In
>Router C bgp table, you will see the 150.50.31.0 network as-path is "200
>100". My question is how to config bgp in router B to filtering as path
>number 100. So router C will
>only 150.50.31.0 network as-path is "200"?
>
> ------------ ------------ ------------
> | Router A |------------| Router B |--------------| Router C |
> | AS 100 | | AS 200 | | AS 300 |
> ------------ ------------ ------------
> 150.50.31.1/24
>
>_________________________________________________________________
>OmSCJ@=gIOWn4s5D5gWSSJ<~O5M3!* MSN Hotmail!# http://www.hotmail.com
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