From: Jason Cash (cash2001@swbell.net)
Date: Wed Jul 02 2003 - 22:20:27 GMT-3
I am working on a BRP issue and this is making absolutely no sense R5 is
getting three routes from BGP neighbors R2 and R6. Here is the topo
R2(s0)----(s0)R5(e0)-----(e0)R6
The problem is when I need to prefer the routes from R1 over R6 (originating
from AS1 over AS9).
R5
!
router bgp 567
no synchronization
bgp log-neighbor-changes
neighbor 192.168.2.2 remote-as 24
neighbor 192.168.2.2 ebgp-multihop 5
neighbor 192.168.2.2 update-source Loopback0
neighbor 192.168.6.6 remote-as 567
neighbor 192.168.6.6 update-source Loopback0
neighbor 192.168.7.7 remote-as 567
neighbor 192.168.7.7 update-source Loopback0
no auto-summary
r5#sb
BGP table version is 5, local router ID is 192.168.5.5
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
* 10.34.19.0/28 192.168.2.2 0 24 1 i
*>i 192.168.9.9 0 100 0 9 i
* 10.34.19.16/28 192.168.2.2 0 24 1 i
*>i 192.168.9.9 0 100 0 9 i
* 10.34.19.32/28 192.168.2.2 0 24 1 i
*>i 192.168.9.9 0 100 0 9 i
*>i172.16.80.0/27 192.168.7.7 0 100 0 7 8 ?
This is where it gets screwed up. I add the following to R5:
ip as-path access-list 1 permit _1
!
access-list 5 permit 10.34.19.0 0.0.0.63
route-map setlp permit 10
match as-path 1
set local-preference 150
!
router bgp 567
neighbor 192.168.2.2 route-map setlp in
Then clear BGP and then, the BGP table looks like this:
r5#sb
BGP table version is 5, local router ID is 192.168.5.5
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
*> 10.34.19.0/28 192.168.2.2 150 0 24 1 i
*> 10.34.19.16/28 192.168.2.2 150 0 24 1 i
*> 10.34.19.32/28 192.168.2.2 150 0 24 1 i
*>i172.16.80.0/27 192.168.7.7 0 100 0 7 8 ?
AARRRH! What the hell is happening? As you can see in a 'debug ip bgp
update' the routes from neighbors 192.168.6.6/.7.7 are being "withdrawn" I
have no idea why. Could someone please
Help on this cause I am banging my head and it isn't to music:
r5#clear ip bgp *
r5#
1d00h: %BGP-5-ADJCHANGE: neighbor 192.168.2.2 Down User reset
1d00h: %BGP-5-ADJCHANGE: neighbor 192.168.6.6 Down User reset
1d00h: %BGP-5-ADJCHANGE: neighbor 192.168.7.7 Down User reset
r5#
r5#
1d00h: %BGP-5-ADJCHANGE: neighbor 192.168.7.7 Up
1d00h: BGP(0): 192.168.7.7 rcvd UPDATE w/ attr: nexthop 192.168.7.7, origin
?, localpref 100, metric 0, path 7 8
1d00h: BGP(0): 192.168.7.7 rcvd 172.16.80.0/27
1d00h: %BGP-5-ADJCHANGE: neighbor 192.168.6.6 Up
1d00h: BGP(0): 192.168.6.6 rcvd UPDATE w/ attr: nexthop 192.168.9.9, origin
i, localpref 100, metric 0, path 9
1d00h: BGP(0): 192.168.6.6 rcvd 10.34.19.0/28
1d00h: BGP(0): 192.168.6.6 rcvd 10.34.19.16/28
1d00h: BGP(0): 192.168.6.6 rcvd 10.34.19.32/28
1d00h: %BGP-5-ADJCHANGE: neighbor 192.168.2.2 Up
1d00h: BGP(0): 192.168.2.2 rcv UPDATE w/ attr: nexthop 192.168.2.2, origin
?, originator 0.0.0.0, path 24 567 7 8, community , extended community
1d00h: BGP(0): 192.168.2.2 rcv UPDATE about 172.16.80.0/27 -- DENIED due to:
AS-PATH contains our own AS;
1d00h: BGP(0): 192.168.2.2 rcvd UPDATE w/ attr: nexthop 192.168.2.2, origin
i, path 24 1
1d00h: BGP(0): 192.168.2.2 rcvd 10.34.19.0/28
1d00h: BGP(0): 192.168.2.2 rcvd 10.34.19.16/28
1d00h: BGP(0): 192.168.2.2 rcvd 10.34.19.32/28
1d00h: BGP(0): Revise route installing 10.34.19.0/28 -> 192.168.2.2 to main
IP table
1d00h: BGP(0): Revise route installing 10.34.19.16/28 -> 192.168.2.2 to main
IP table
1d00h: BGP(0): Revise route installing 10.34.19.32/28 -> 192.168.2.2 to main
IP table
1d00h: BGP(0): Revise route installing 172.16.80.0/27 -> 192.168.7.7 to main
IP table
1d00h: BGP(0): 192.168.6.6 computing updates, afi 0, neighbor version 0,
table version 5, starting at 0.0.0.0
1d00h: BGP(0): 192.168.6.6 NEXT_HOP part 1 net 10.34.19.0/28, next
192.168.2.2
1d00h: BGP(0): 192.168.6.6 send UPDATE (format) 10.34.19.0/28, next
192.168.2.2, metric 0, path 24 1
1d00h: BGP(0): 192.168.6.6 NEXT_HOP part 1 net 10.34.19.16/28, next
192.168.2.2
1d00h: BGP(0): 192.168.6.6 send UPDATE (prepend, chgflags: 0x208)
10.34.19.16/28, next 192.168.2.2, metric 0, path 24 1
1d00h: BGP(0): 192.168.6.6 NEXT_HOP part 1 net 10.34.19.32/28, next
192.168.2.2
1d00h: BGP(0): 192.168.6.6 send UPDATE (prepend, chgflags: 0x208)
10.34.19.32/28, next 192.168.2.2, metric 0, path 24 1
1d00h: BGP(0): 192.168.6.6 1 updates enqueued (average=65, maximum=65)
1d00h: BGP(0): 192.168.6.6 update run completed, afi 0, ran for 40ms,
neighbor version 0, start version 5, throttled to 5
1d00h: BGP: 192.168.6.6 initial update completed
1d00h: BGP(0): 192.168.7.7 computing updates, afi 0, neighbor version 0,
table version 5, starting at 0.0.0.0
1d00h: BGP(0): 192.168.7.7 NEXT_HOP part 1 net 10.34.19.0/28, next
192.168.2.2
1d00h: BGP(0): 192.168.7.7 send UPDATE (format) 10.34.19.0/28, next
192.168.2.2, metric 0, path 24 1
1d00h: BGP(0): 192.168.7.7 NEXT_HOP part 1 net 10.34.19.16/28, next
192.168.2.2
1d00h: BGP(0): 192.168.7.7 send UPDATE (prepend, chgflags: 0x208)
10.34.19.16/28, next 192.168.2.2, metric 0, path 24 1
1d00h: BGP(0): 192.168.7.7 NEXT_HOP part 1 net 10.34.19.32/28, next
192.168.2.2
1d00h: BGP(0): 192.168.7.7 send UPDATE (prepend, chgflags: 0x208)
10.34.19.32/28, next 192.168.2.2, metric 0, path 24 1
1d00h: BGP(0): 192.168.7.7 1 updates enqueued (average=65, maximum=65)
1d00h: BGP(0): 192.168.7.7 update run completed, afi 0, ran for 40ms,
neighbor version 0, start version 5, throttled to 5
1d00h: BGP: 192.168.7.7 initial update completed
1d00h: BGP(0): 192.168.6.6 rcv UPDATE about 10.34.19.0/28 -- withdrawn
1d00h: BGP(0): 192.168.6.6 rcv UPDATE about 10.34.19.16/28 -- withdrawn
1d00h: BGP(0): 192.168.6.6 rcv UPDATE about 10.34.19.32/28 -- withdrawn
1d00h: BGP(0): 192.168.2.2 computing updates, afi 0, neighbor version 0,
table version 5, starting at 0.0.0.0
1d00h: BGP(0): 192.168.2.2 send UPDATE (format) 172.16.80.0/27, next
192.168.5.5, metric 0, path 7 8
1d00h: BGP(0): 192.168.2.2 1 updates enqueued (average=50, maximum=50)
1d00h: BGP(0): 192.168.2.2 update run completed, afi 0, ran for 16ms,
neighbor version 0, start version 5, throttled to 5
1d00h: BGP: 192.168.2.2 initial update completed
r5#
r5#sb
BGP table version is 5, local router ID is 192.168.5.5
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
*> 10.34.19.0/28 192.168.2.2 150 0 24 1 i
*> 10.34.19.16/28 192.168.2.2 150 0 24 1 i
*> 10.34.19.32/28 192.168.2.2 150 0 24 1 i
*>i172.16.80.0/27 192.168.7.7 0 100 0 7 8 ?
This archive was generated by hypermail 2.1.4 : Wed Aug 06 2003 - 06:52:20 GMT-3