From: DougAtHome (dcalton@fuse.net)
Date: Thu Apr 17 2003 - 08:58:22 GMT-3
I had similar problems last week. After I turned on debug ip routing, I
would see that routing installed the RIP entry in the routing table first,
while BGP was futzing around with establishing neighbor sessions. When BGP
came up, the route was replaced by BGP. Then, as you said, after 5 minutes,
it went to possibly down. My theory was and still is that the table is a
bit "poluted" and, although it knows that it is no longer an RIP route, it
still looks for RIP updates which never arrive. Since it was a lab
situation, I filtered out the redundant loops from RIP, allowing BGP to be
the sole source of these updates. I still suspect an IOS bug here, but
since I make my first attempt for the R&S Lab on the 27th, who has time to
research this one?
-----Original Message-----
From: Hunt Lee [mailto:huntl@webcentral.com.au]
Sent: Wednesday, April 16, 2003 9:12 PM
To: 'ccielab@groupstudy.com'
Subject: BGP problem
Hi Group,
... - r6 --- r13 - Loopback 0 (198.5.51.1/24)
- Loopback 1 (198.5.52.1/24)
- Loopback 2 (198.5.53.1/24)
- Loopback 0 (198.5.54.1/24)
The link between the routers are EBGP, and they are also talking in RIPv1.
...and there are some OSPF routers on the left of r6. And r6 is part of a
BGP confederation with the routers on the left.
r13's interface (to r6) - 200.100.100.13 /24
All 4 loopbacks are advertised by RIPv1 as well as BGP.
Ok. What I don't understand is that when r6 first boots up, it can see the
4 BGP routes fine, & can ping fine also...
r6#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter
area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
C 200.100.100.0/24 is directly connected, Ethernet0
R 172.16.0.0/16 [120/2] via 200.100.100.13, 00:00:05, Ethernet0
B 198.5.51.0/24 [20/0] via 200.100.100.13, 00:01:27
B 198.5.53.0/24 [20/0] via 200.100.100.13, 00:01:27
B 198.6.53.0/24 [200/0] via 150.10.2.2, 00:00:57
B 198.5.52.0/24 [20/0] via 200.100.100.13, 00:01:27
B 198.5.54.0/24 [20/0] via 200.100.100.13, 00:01:27
150.10.0.0/16 is variably subnetted, 13 subnets, 5 masks
O IA 150.10.20.0/25 [110/129] via 150.10.60.5, 00:00:05, Serial0
O IA 150.10.10.0/28 [110/128] via 150.10.60.5, 00:00:05, Serial0
O E2 150.10.4.0/24 [110/20] via 150.10.60.5, 00:00:05, Serial0
C 150.10.6.0/24 is directly connected, Loopback0
O IA 150.10.5.5/32 [110/65] via 150.10.60.5, 00:00:05, Serial0
O IA 150.10.2.2/32 [110/129] via 150.10.60.5, 00:00:05, Serial0
O IA 150.10.1.1/32 [110/129] via 150.10.60.5, 00:00:05, Serial0
O E2 150.10.3.0/24 [110/20] via 150.10.60.5, 00:00:05, Serial0
C 150.10.60.0/24 is directly connected, Serial0
O IA 150.10.50.0/24 [110/128] via 150.10.60.5, 00:00:05, Serial0
O E2 150.10.45.0/24 [110/20] via 150.10.60.5, 00:00:05, Serial0
O E2 150.10.40.0/24 [110/20] via 150.10.60.5, 00:00:05, Serial0
C 150.10.65.0/30 is directly connected, BRI0
B 198.6.48.0/21 [200/0] via 150.10.2.2, 00:00:59
r6#
r6#ping 198.5.51.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.5.51.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/8 ms
r6#ping 198.5.52.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.5.52.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/8 ms
r6#ping 198.5.53.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.5.53.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/3/4 ms
r6#ping 198.5.54.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.5.54.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms
r6#
r6#sh ip bgp
BGP table version is 11, local router ID is 150.10.6.6
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
*> 150.10.3.0/24 150.10.10.3 50 100 0 (250) i
*> 150.10.20.0/25 150.10.10.3 100 100 0 (250) i
*> 150.10.45.0/24 150.10.40.4 100 100 0 (250) i
*> 150.10.50.0/24 150.10.5.5 50 100 0 (250) i
*> 198.5.51.0 200.100.100.13 0 1000 130 i
*> 198.5.52.0 200.100.100.13 0 1000 130 i
*> 198.5.53.0 200.100.100.13 0 1000 130 i
*> 198.5.54.0 200.100.100.13 0 1000 130 i
*> 198.6.48.0/21 150.10.2.2 100 0 (250 8) i
*> 198.6.53.0 150.10.2.2 0 100 0 (250 8) 1000 i
r6#
But if you wait for around 3 mins, those 4 routes would say "...is possibly
down", which I have never seen on a BGP route before (a BGP route is
normally either there or not there, rather than saying "is possibly down".
r6#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter
area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
C 200.100.100.0/24 is directly connected, Ethernet0
R 172.16.0.0/16 [120/2] via 200.100.100.13, 00:00:02, Ethernet0
B 198.5.51.0/24 is possibly down, routing via 200.100.100.13
B 198.5.53.0/24 is possibly down, routing via 200.100.100.13
B 198.6.53.0/24 [200/0] via 150.10.2.2, 00:05:54
B 198.5.52.0/24 is possibly down, routing via 200.100.100.13
B 198.5.54.0/24 is possibly down, routing via 200.100.100.13
150.10.0.0/16 is variably subnetted, 13 subnets, 5 masks
O IA 150.10.20.0/25 [110/129] via 150.10.60.5, 00:05:02, Serial0
O IA 150.10.10.0/28 [110/128] via 150.10.60.5, 00:05:02, Serial0
O E2 150.10.4.0/24 [110/20] via 150.10.60.5, 00:05:02, Serial0
C 150.10.6.0/24 is directly connected, Loopback0
O IA 150.10.5.5/32 [110/65] via 150.10.60.5, 00:05:02, Serial0
O IA 150.10.2.2/32 [110/129] via 150.10.60.5, 00:05:03, Serial0
O IA 150.10.1.1/32 [110/129] via 150.10.60.5, 00:05:03, Serial0
O E2 150.10.3.0/24 [110/20] via 150.10.60.5, 00:05:03, Serial0
C 150.10.60.0/24 is directly connected, Serial0
O IA 150.10.50.0/24 [110/128] via 150.10.60.5, 00:05:03, Serial0
O E2 150.10.45.0/24 [110/20] via 150.10.60.5, 00:05:03, Serial0
O E2 150.10.40.0/24 [110/20] via 150.10.60.5, 00:05:03, Serial0
C 150.10.65.0/30 is directly connected, BRI0
B 198.6.48.0/21 [200/0] via 150.10.2.2, 00:05:56
r6#
r6#sh ip bgp
BGP table version is 11, local router ID is 150.10.6.6
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
*> 150.10.3.0/24 150.10.10.3 50 100 0 (250) i
*> 150.10.20.0/25 150.10.10.3 100 100 0 (250) i
*> 150.10.45.0/24 150.10.40.4 100 100 0 (250) i
*> 150.10.50.0/24 150.10.5.5 50 100 0 (250) i
*> 198.5.51.0 200.100.100.13 0 1000 130 i
*> 198.5.52.0 200.100.100.13 0 1000 130 i
*> 198.5.53.0 200.100.100.13 0 1000 130 i
*> 198.5.54.0 200.100.100.13 0 1000 130 i
*> 198.6.48.0/21 150.10.2.2 100 0 (250 8) i
*> 198.6.53.0 150.10.2.2 0 100 0 (250 8) 1000 i
r6#
r6#ping 198.5.51.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 198.5.51.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
r6#sh ip route 198.5.51.1
Routing entry for 198.5.51.0/24
Known via "bgp 6", distance 20, metric 4294967295 (inaccessible)
Tag 130, type external
Last update from 200.100.100.13 00:04:10 ago
Hold down timer expires in 120 secs
r6#
Does this have anything to do with RIPv1 + BGP using together?
Anyway, here are the configs for the 2 routers ;)
For r6:-
interface Ethernet0
ip address 200.100.100.6 255.255.255.0
ip pim sparse-mode
router ospf 1
log-adjacency-changes
area 5 authentication message-digest
redistribute rip metric 65 metric-type 1 subnets route-map Even
network 150.10.6.6 0.0.0.0 area 5
network 150.10.60.6 0.0.0.0 area 5
network 150.10.65.2 0.0.0.0 area 5
!
router rip
redistribute ospf 1 metric 2
passive-interface BRI0
network 200.100.100.0
router bgp 6
no synchronization
bgp log-neighbor-changes
bgp confederation identifier 22
bgp confederation peers 250
neighbor 150.10.5.5 remote-as 250
neighbor 150.10.5.5 ebgp-multihop 255
neighbor 150.10.5.5 update-source Loopback0
neighbor 150.10.5.5 next-hop-self
neighbor 200.100.100.13 remote-as 130
neighbor 200.100.100.13 route-map Weight in
neighbor 200.100.100.13 filter-list 2 out
no auto-summary
ip as-path access-list 2 permit ^$
ip pim rp-address 150.10.5.5
route-map Weight permit 10
set weight 1000
route-map Even permit 10
match ip address 1
access-list 1 permit 198.5.0.0 0.0.254.255
access-list 1 permit 200.0.0.0 0.255.255.255
access-list 1 permit 172.16.0.0 0.0.255.255
access-list 1 permit 10.0.0.0 0.255.255.255
... and for r13:-
interface Loopback0
ip address 198.5.51.1 255.255.255.0
!
interface Loopback1
ip address 198.5.52.1 255.255.255.0
!
interface Loopback2
ip address 198.5.53.1 255.255.255.0
!
interface Loopback3
ip address 198.5.54.1 255.255.255.0
interface FastEthernet0/0
ip address 200.100.100.13 255.255.255.0
ip pim sparse-mode
ip igmp join-group 224.0.5.5
speed 100
full-duplex
router rip
redistribute static metric 2
network 198.5.51.0
network 198.5.52.0
network 198.5.53.0
network 198.5.54.0
network 200.100.100.0
!
router bgp 130
bgp log-neighbor-changes
network 198.5.51.0
network 198.5.52.0
network 198.5.53.0
network 198.5.54.0
neighbor 200.100.100.6 remote-as 22
no auto-summary
ip route 172.16.1.0 255.255.255.0 10.1.1.14
!
end
Any help will be greatly appreciated.
Regards,
Hunt
This archive was generated by hypermail 2.1.4 : Thu May 01 2003 - 13:35:55 GMT-3