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- About matthewaho
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02-18-2014
12:15 PM
Leaving my above post in place just so folks can see a snapshot of the various parts of the routing if necessary. Jon, you're right! I swear I tried modifying the WEIGHT for relevant networks with a route-map before and experienced the same behavior. However, I just tried it again and it's failing back as expected now. The BGP table shows only the MPLS route now and the OSPF route is visible in the OSPF RIB but is not used. Thanks for the assistance in helping me walk through this! No idea what I was doing before to mess it up, but it appears to be correct now. ------ ROUTE MAP CONFIG FROM RTR A ip access-list standard WEIGHT permit 20.20.20.0 0.0.0.255 permit 1.1.1.0 0.0.0.3 permit 2.2.2.0 0.0.0.3 ! ! ! ! ! route-map WEIGHT permit 10 match ip address WEIGHT set weight 35000 ! route-map WEIGHT permit 20 router bgp 100 bgp log-neighbor-changes network 1.1.1.0 mask 255.255.255.252 redistribute connected redistribute ospf 1 match internal external 1 external 2 neighbor 1.1.1.2 remote-as 300 neighbor 1.1.1.2 next-hop-self neighbor 1.1.1.2 soft-reconfiguration inbound neighbor 1.1.1.2 route-map WEIGHT in distance 100 1.1.1.2 0.0.0.0 ------ Rtr-A#sh ip route Codes: L - local, C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set 1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 1.1.1.0/30 is directly connected, GigabitEthernet0/0 L 1.1.1.1/32 is directly connected, GigabitEthernet0/0 2.0.0.0/30 is subnetted, 1 subnets B 2.2.2.0 [100/0] via 1.1.1.2, 00:01:06 5.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 5.5.5.0/30 is directly connected, GigabitEthernet2/0 L 5.5.5.1/32 is directly connected, GigabitEthernet2/0 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.10.10.0/24 is directly connected, GigabitEthernet1/0 L 10.10.10.1/32 is directly connected, GigabitEthernet1/0 20.0.0.0/24 is subnetted, 1 subnets B 20.20.20.0 [100/0] via 1.1.1.2, 00:01:06 Rtr-A#sh ip bgp BGP table version is 23, local router ID is 10.10.10.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path r> 1.1.1.0/30 1.1.1.2 0 35000 300 i r 0.0.0.0 0 32768 i *> 2.2.2.0/30 1.1.1.2 0 35000 300 i * 5.5.5.0/30 1.1.1.2 0 300 200 ? *> 0.0.0.0 0 32768 ? * 10.10.10.0/24 1.1.1.2 0 300 200 ? *> 0.0.0.0 0 32768 ? *> 20.20.20.0/24 1.1.1.2 35000 300 200 ? Rtr-A#sh ip ospf rib OSPF Router with ID (10.10.10.1) (Process ID 1) Base Topology (MTID 0) OSPF local RIB Codes: * - Best, > - Installed in global RIB * 5.5.5.0/30, Intra, cost 1, area 0, Connected via 5.5.5.1, GigabitEthernet2/0 * 10.10.10.0/24, Intra, cost 1, area 0, Connected via 10.10.10.1, GigabitEthernet1/0 * 20.20.20.0/24, Intra, cost 2, area 0 via 5.5.5.2, GigabitEthernet2/0
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02-18-2014
12:12 PM
Thanks for pointing that out, Jon. You're correct. I cobbled this diagram from a setup with a second router between the customer router and the upstream router which made it iBGP routes that I had to modify the AD on. You're 100% correct. In this case I shouldn't need to modify the AD for the BGP routes to be preferred over the OSPF routes. Below is the IP and BGP tables as well as the OSPF RIB from Rtr A in three circumstances. ------------------------------------------------------------------------- The primary MPLS connection is up originally: Rtr-A#sh ip route Codes: L - local, C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set 1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 1.1.1.0/30 is directly connected, GigabitEthernet0/0 L 1.1.1.1/32 is directly connected, GigabitEthernet0/0 2.0.0.0/30 is subnetted, 1 subnets B 2.2.2.0 [100/0] via 1.1.1.2, 00:01:59 5.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 5.5.5.0/30 is directly connected, GigabitEthernet2/0 L 5.5.5.1/32 is directly connected, GigabitEthernet2/0 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.10.10.0/24 is directly connected, GigabitEthernet1/0 L 10.10.10.1/32 is directly connected, GigabitEthernet1/0 20.0.0.0/24 is subnetted, 1 subnets B 20.20.20.0 [100/0] via 1.1.1.2, 00:01:00 Rtr-A#sh ip bgp BGP table version is 23, local router ID is 10.10.10.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * 1.1.1.0/30 1.1.1.2 0 0 300 i *> 0.0.0.0 0 32768 i *> 2.2.2.0/30 1.1.1.2 0 0 300 i * 5.5.5.0/30 1.1.1.2 0 300 200 ? *> 0.0.0.0 0 32768 ? *> 10.10.10.0/24 0.0.0.0 0 32768 ? *> 20.20.20.0/24 1.1.1.2 0 300 200 ? Rtr-A#sh ip ospf rib OSPF Router with ID (10.10.10.1) (Process ID 1) Base Topology (MTID 0) OSPF local RIB Codes: * - Best, > - Installed in global RIB * 5.5.5.0/30, Intra, cost 50000, area 0, Connected via 5.5.5.1, GigabitEthernet2/0 * 10.10.10.0/24, Intra, cost 1, area 0, Connected via 10.10.10.1, GigabitEthernet1/0 * 20.20.20.0/24, Intra, cost 50001, area 0 via 5.5.5.2, GigabitEthernet2/0 ---------------------------- The MPLS connection is down (failover): Rtr-A#sh ip route Codes: L - local, C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set 1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 1.1.1.0/30 is directly connected, GigabitEthernet0/0 L 1.1.1.1/32 is directly connected, GigabitEthernet0/0 5.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 5.5.5.0/30 is directly connected, GigabitEthernet2/0 L 5.5.5.1/32 is directly connected, GigabitEthernet2/0 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.10.10.0/24 is directly connected, GigabitEthernet1/0 L 10.10.10.1/32 is directly connected, GigabitEthernet1/0 20.0.0.0/24 is subnetted, 1 subnets O 20.20.20.0 [110/50001] via 5.5.5.2, 00:00:07, GigabitEthernet2/0 Rtr-A#sh ip bgp BGP table version is 1, local router ID is 10.10.10.1 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter Origin codes: i - IGP, e - EGP, ? - incomplete Network Next Hop Metric LocPrf Weight Path * 20.20.20.0/24 5.5.5.2 50001 32768 ? Rtr-A#sh ip ospf rib OSPF Router with ID (10.10.10.1) (Process ID 1) Base Topology (MTID 0) OSPF local RIB Codes: * - Best, > - Installed in global RIB * 5.5.5.0/30, Intra, cost 50000, area 0, Connected via 5.5.5.1, GigabitEthernet2/0 * 10.10.10.0/24, Intra, cost 1, area 0, Connected via 10.10.10.1, GigabitEthernet1/0 *> 20.20.20.0/24, Intra, cost 50001, area 0 via 5.5.5.2, GigabitEthernet2/0 Rtr-A# ---------------- The MPLS connection is restored (should move back to MPLS, but remains on failover): Rtr-A#sh ip route Codes: L - local, C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP + - replicated route, % - next hop override Gateway of last resort is not set 1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 1.1.1.0/30 is directly connected, GigabitEthernet0/0 L 1.1.1.1/32 is directly connected, GigabitEthernet0/0 5.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 5.5.5.0/30 is directly connected, GigabitEthernet2/0 L 5.5.5.1/32 is directly connected, GigabitEthernet2/0 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.10.10.0/24 is directly connected, GigabitEthernet1/0 L 10.10.10.1/32 is directly connected, GigabitEthernet1/0 20.0.0.0/24 is subnetted, 1 subnets O 20.20.20.0 [110/50001] via 5.5.5.2, 00:01:10, GigabitEthernet2/0 Network Next Hop Metric LocPrf Weight Path * 1.1.1.0/30 1.1.1.2 0 0 300 i * 0.0.0.0 0 32768 i * 2.2.2.0/30 1.1.1.2 0 0 300 i * 5.5.5.0/30 1.1.1.2 0 300 200 ? * 0.0.0.0 0 32768 ? * 10.10.10.0/24 1.1.1.2 0 300 200 ? * 0.0.0.0 0 32768 ? * 20.20.20.0/24 1.1.1.2 0 300 200 ? * 5.5.5.2 50001 32768 ?
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02-18-2014
10:45 AM
Diagram is attached. Router A and Router B are separate customer sites. Each location is running OSPF as their IGP and BGP as the protocol to peer with their upstream carrier device (Rtr C). Rtr A and Rtr B also share a direct point-to-point connection between them and are OSPF neighbors. On both Rtr A and Rtr B OSPF and BGP are redistributed into each other to provide two paths to each subnet, 10.10.10.0/24 and 20.20.20.0 /24 respectively, either through the carrier connection or through the direct point-to-point connection. I wish to have the carrier connection be the preferred route and the point-to-point connection between locations be the secondary or failover connection. I've employed the BGP distance command on Rtr A and Rtr B so that all routes received from the upstream carrier device are given an Administrative Distance of 100 so that they take priority over the 110 AD of the internal OSPF. This part works fine. I am able to take down the connection between Rtr A and Rtr C and all traffic re-routes across the point-to-point connection as expected. The OSPF route over the point-to-point connection is installed in the routing table as expected. However, when I restore the connection between Rtr A and Rtr C the BGP route does not replace the OSPF route when it returns. The OSPF route over the point-to-point connection remains unless I clear the OSPF process in which case the BGP route will take over. Any ideas on why BGP would not take precedence over an already installed OSPF route in this case? I've tried accounting for the METRIC and WEIGHT of the BGP routes as well with route-maps but this hasn't fixed the issue. Configs are as below: ---Rtr A--- ! hostname Rtr-A ! interface GigabitEthernet0/0 ip address 1.1.1.1 255.255.255.252 ! interface GigabitEthernet0/1 ip address 10.10.10.1 255.255.255.0 ! interface GigabitEthernet0/2 ip address 5.5.5.1 255.255.255.252 ip ospf cost 50000 ! router bgp 100 network 1.1.1.0 mask 255.255.255.252 redistribute connected redistribute ospf 1 match internal external 1 external 2 neighbor 1.1.1.2 remote-as 300 neighbor 1.1.1.2 soft-reconfiguration inbound distance 100 1.1.1.2 0.0.0.0 ! router ospf 1 redistribute bgp 100 metric 100 network 10.10.10.0 0.0.0.255 area 0 network 5.5.5.0 0.0.0.3 area 0 ---Rtr B--- ! hostname Rtr-B ! interface GigabitEthernet0/0 ip address 20.20.20.1 255.255.255.0 ! interface GigabitEthernet0/1 ip address 2.2.2.1 255.255.255.252 ! interface GigabitEthernet0/2 ip address 5.5.5.2 255.255.255.252 ip ospf cost 50000 ! router bgp 200 network 2.2.2.0 mask 255.255.255.252 redistribute connected redistribute ospf 1 match internal external 1 external 2 neighbor 2.2.2.2 remote-as 300 neighbor 2.2.2.2 soft-reconfiguration inbound distance 100 2.2.2.2 0.0.0.0 ! router ospf 1 redistribute bgp 200 metric 100 network 20.20.20.0 0.0.0.255 area 0 network 5.5.5.0 0.0.0.3 area 0 ---Rtr C--- ! hostname Rtr-C ! interface GigabitEthernet0/0 ip address 1.1.1.2 255.255.255.252 ! interface GigabitEthernet0/1 ip address 2.2.2.2 255.255.255.252 ! interface GigabitEthernet0/2 ip address 222.222.222.1 255.255.255.252 ! router bgp 300 network 1.1.1.0 mask 255.255.255.252 network 2.2.2.0 mask 255.255.255.252 neighbor 1.1.1.1 remote-as 100 neighbor 1.1.1.1 soft-reconfiguration inbound neighbor 1.1.1.1 next-hop-self neighbor 2.2.2.2 remote-as 200 neighbor 2.2.2.2 soft-reconfiguration inbound neighbor 2.2.2.2 next-hop-self ! ip route 0.0.0.0 0.0.0.0 222.222.222.2
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02-18-2014
Leaving my above post in place just so folks can see a snapshot of the
various parts of the routing ...
02-18-2014
Thanks for pointing that out, Jon. You're correct. I cobbled this
diagram from a setup with a second...
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