From: Neil Garcia Legada (nlegs@xxxxxxxxx)
Date: Fri Nov 30 2001 - 08:14:28 GMT-3
Try this ...
router bgp 620
neighbor 216.30.1.4 distribute-list 101 out
access-list 101 deny ip host 172.16.0.0 host 255.255.0.0
access-list 101 permit ip any any
-----Original Message-----
From: Albert Lu albert_ccie@yahoo.com
Sent: Fri, 30 Nov 2001 21:44:50 +1100
To: ccielab@groupstudy.com
Subject: BGP Aggregate Route feeding back.
Hello Group,
I got a problem with BGP aggregate route being advertised out to another AS,
and then readvertised back to the original AS through another entry router.
R5_________R6
|
R7
Basically an ethernet segment R5, R6, R7 on the same subnet. R5 & R6 in
AS600, and R7 in AS500. R5 sends out an aggregate of 172.16.0.0/16 to R7,
and then somehow R6 learns this aggregate route also.
Configs:
R5#
router bgp 620
no synchronization
bgp router-id 10.10.10.5
bgp log-neighbor-changes
bgp confederation identifier 600
aggregate-address 172.16.0.0 255.255.0.0 as-set suppress-map sup_map
neighbor 10.10.10.4 remote-as 620
neighbor 10.10.10.4 update-source Loopback0
neighbor 10.10.10.7 remote-as 500
neighbor 10.10.10.7 ebgp-multihop 2
neighbor 10.10.10.7 update-source Loopback0
neighbor 10.10.10.7 route-map set_med out
no auto-summary
!
BGP table version is 16, local router ID is 10.10.10.5
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
*> 172.16.0.0 0.0.0.0 100 32768 (610) i
<--------******* Source of aggregate
s>i172.16.1.0/24 216.30.30.2 0 100 0 (610) i
s>i172.16.2.0/24 216.30.30.2 0 100 0 (610) i
s>i172.16.3.0/24 216.30.30.2 0 100 0 (610) i
*>i172.16.4.0/24 216.30.30.2 0 100 0 (610) i
*> 192.168.22.0 10.10.10.7 0 500 400 i
R5#
R6#
router bgp 620
no synchronization
bgp router-id 10.10.10.6
bgp log-neighbor-changes
bgp confederation identifier 600
neighbor 10.10.10.4 remote-as 620
neighbor 10.10.10.4 update-source Loopback0
neighbor 10.10.10.7 remote-as 500
neighbor 10.10.10.7 ebgp-multihop 2
neighbor 10.10.10.7 update-source Loopback0
neighbor 10.10.10.7 route-map set_med out
no auto-summary
!
BGP table version is 24, local router ID is 10.10.10.6
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
*>i172.16.0.0 10.10.10.5 100 0 (610) i
<--------- Somehow R6 learns it as well
*>i172.16.1.0/24 216.30.30.2 0 100 0 (610) i
*>i172.16.2.0/24 216.30.30.2 0 100 0 (610) i
*>i172.16.3.0/24 216.30.30.2 0 100 0 (610) i
*>i172.16.4.0/24 216.30.30.2 0 100 0 (610) i
* i192.168.22.0 10.10.10.7 100 0 500 400 i
*> 10.10.10.7 0 500 400 i
R6#
R7#
router bgp 500
bgp router-id 10.10.10.7
bgp log-neighbor-changes
neighbor 10.10.10.5 remote-as 600
neighbor 10.10.10.5 ebgp-multihop 2
neighbor 10.10.10.5 update-source Loopback0
neighbor 10.10.10.6 remote-as 600
neighbor 10.10.10.6 ebgp-multihop 2
neighbor 10.10.10.6 update-source Loopback0
neighbor 10.10.10.6 route-map change_weight in
neighbor 10.10.10.8 remote-as 400
neighbor 10.10.10.8 ebgp-multihop 2
neighbor 10.10.10.8 update-source Loopback0
maximum-paths 2
no auto-summary
!
BGP table version is 9, local router ID is 10.10.10.7
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
*> 172.16.0.0 10.10.10.5 0 600 i <--------
Sent out to R7
* 10.10.10.5 0 600 i <--------
Some how learnt it twice
*> 172.16.1.0/24 10.10.10.6 150 600 i
*> 172.16.2.0/24 10.10.10.6 0 600 i
*> 172.16.3.0/24 10.10.10.6 0 600 i
*> 172.16.4.0/24 10.10.10.5 50 0 600 i
* 10.10.10.6 100 0 600 i
*> 192.168.22.0 10.10.10.8 0 0 400 i
R7#
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