From: Rich West (westrk102002@yahoo.com)
Date: Sat Sep 21 2002 - 12:46:17 GMT-3
There is a gotcha when redistributing BGP into OSPF. You must use the command 'bgp redistribute-internal' under your BGP AS. Since you normally don't redistribute BGP into an IGP, this is a little safety valve. Hope this works for you.
-Rich
Hunt Lee wrote:Hello,
When redistributing OSPF into BGP, I know that one needs to use the
"match" keyword:-
http://www.cisco.com/warp/public/104/bgp-ospf-redis.html
But today, when I tried to do the other way round, by redistributing
BGP into OSPF. I tried everything but I couldn't get the BGP route to
be redistributed into OSPF. Is there any rules or gotcha about
redistributing BGP routes into OSPF?
RTA --- RTB ----- RTC --- 3.3.3.3/32
IBGP
The network 3.3.3.3/32 is advertised into the network by BGP's network
command at RTC. Both RTB & RTC have used the "no synch" command. RTA
& RTB are OSPF Area 0, and RTB is the ASBR (redistributing BGP routes
into OSPF).
RouterB#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
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/65] via 10.1.1.1, 00:03:24, Serial1
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback0
3.0.0.0/32 is subnetted, 1 subnets
B 3.3.3.3 [200/0] via 10.1.1.6, 00:00:27
10.0.0.0/30 is subnetted, 2 subnets
C 10.1.1.0 is directly connected, Serial1
C 10.1.1.4 is directly connected, Serial0
RouterB#sh ip bgp
BGP table version is 2, local router ID is 2.2.2.2
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
*>i3.3.3.3/32 10.1.1.6 0 100 0 i
RouterB#ping 3.3.3.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/31/32 ms
RouterB#
As illustrated above, I can see the BGP route 3.3.3.3/32 fine at RTB's
Routing Table & BGP table. But I just couldn't redistribute this BGP
route into OSPF.
At RTB:
router ospf 2
log-adjacency-changes
redistribute bgp 2 subnets
passive-interface Serial0
network 2.2.2.2 0.0.0.0 area 2
network 10.1.1.0 0.0.0.3 area 0
!
router bgp 2
no synchronization
bgp log-neighbor-changes
neighbor 10.1.1.6 remote-as 2
RouterB#sh ip ospf database
OSPF Router with ID (2.2.2.2) (Process ID 2)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link
count
1.1.1.1 1.1.1.1 166 0x80000004 0x6A10 2
2.2.2.2 2.2.2.2 199 0x80000006 0xC65 2
Summary Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 1.1.1.1 166 0x80000003 0x43EE
2.2.2.2 2.2.2.2 199 0x80000003 0xF633
Router Link States (Area 2)
Link ID ADV Router Age Seq# Checksum Link
count
2.2.2.2 2.2.2.2 199 0x80000003 0xAB69 1
Summary Net Link States (Area 2)
Link ID ADV Router Age Seq# Checksum
1.1.1.1 2.2.2.2 199 0x80000003 0xA746
10.1.1.0 2.2.2.2 200 0x80000003 0x20C9
RouterB#
Hence, I can't see the 3.3.3.3/32 route at RTA's Routing Table.
RouterA>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
1.0.0.0/32 is subnetted, 1 subnets
C 1.1.1.1 is directly connected, Loopback0
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/65] via 10.1.1.2, 00:08:12, Serial0
10.0.0.0/30 is subnetted, 1 subnets
C 10.1.1.0 is directly connected, Serial0
RouterA>
It would be greatly appreciated if anyone can shed some light onto
this.
Best Regards,
L.
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