Hello,
I have a question that I hope someone would be able to help. Basically, I have a router (D1) that has two links to two different remote routers (Core-RT and NRR1). D1 runs OSPF with Core-RT while D1 runs EBGP with NRR1. When I ping a host (MMS) on another router (Node1) that connects to Core-RT, OSPF will be the used as the preferred routing protocol because D1 learns that host via OSPF routing process. When I shutdown the OSPF link between D1 and the Core-RT, the link switches to use BGP between D1 and NRR1 as expected because it is the only path available. It takes about 20 to 24 pings dropped before D1 can detect that the OSPF path is no longer available before switching over to BGP.
When I bring back the OSPF link, the ping continues to traverse the BGP link to reach to the host unless I either (1) perform a "clear ip bgp *" on D1 or (2) perform a "shutdown" on the link that connects between D1 and NRR1 to force the traffic originated from D1 to use OSPF.
My question is is there a way to configure D1's BGP routing process to trigger the switchover from BGP to OSPF sooner instead of performing either one of the actions above?
Below are the configuration files for D1, Core-RT and NRR1 along with the topology. Thank you in advance.
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!
hostname DUCE1-RR1
!
interface Loopback0
description "D1 - Router Loopback IP Address"
ip address 11.11.11.11 255.255.255.255
ip ospf 100 area 0
!
interface Ethernet0/0
description "Link to WAN - Router"
ip address 10.10.100.1 255.255.255.0
!
interface Ethernet0/1
description "Link to S1 - Core Router"
ip address 10.10.110.1 255.255.255.0
ip ospf 100 area 0
!
interface Ethernet0/2
description "Link to D1 - Workstation #1"
ip address 10.10.120.1 255.255.255.0
ip ospf 100 area 0
!
router ospf 100
router-id 11.11.11.11
redistribute bgp 400 subnets
!
router bgp 400
bgp router-id 11.11.11.11
bgp log-neighbor-changes
network 11.11.11.11 mask 255.255.255.255
redistribute ospf 100
neighbor 10.10.100.2 remote-as 300
neighbor 10.10.100.2 update-source Ethernet0/0
neighbor 10.10.100.2 allowas-in
!
end
D1-RR1#
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!
hostname Core-RT
!
interface Loopback0
description "S1 Core Router Loopback IP Address"
ip address 2.2.2.2 255.255.255.255
ip ospf 100 area 0
!
interface Ethernet0/0
description "Link to S1U-SW - Switch"
ip address 10.10.150.2 255.255.255.0
ip ospf 100 area 0
!
interface Ethernet0/1
description "Link to S1 - RSW"
ip address 10.10.30.2 255.255.255.0
ip ospf 100 area 0
!
interface Ethernet0/2
description "Link to D1 - Router"
ip address 10.10.110.2 255.255.255.0
ip ospf 100 area 0
!
interface Ethernet1/0
description "Link to WAN - Router"
ip address 10.10.20.2 255.255.255.0
!
router ospf 100
router-id 2.2.2.2
redistribute bgp 400 metric-type 1 subnets route-map BGP-To-OSPF
!
router bgp 400
bgp router-id 2.2.2.2
bgp log-neighbor-changes
bgp redistribute-internal
network 2.2.2.2 mask 255.255.255.255
network 10.10.20.0 mask 255.255.255.0
redistribute ospf 100 route-map OSPF-To-BGP
neighbor 10.10.10.1 remote-as 400
neighbor 10.10.10.1 update-source Ethernet0/1
neighbor 10.10.20.1 remote-as 300
neighbor 10.10.20.1 update-source Ethernet1/0
neighbor 10.10.20.1 allowas-in
!
route-map OSPF-To-BGP permit 10
match ip address 1
!
route-map BGP-To-OSPF permit 20
match ip address 2
!
!
access-list 1 remark Access List to Control OSPF-To-BGP Traffic
access-list 1 permit 1.1.1.1 log
access-list 1 permit 4.4.4.4 log
access-list 1 permit 25.25.25.25 log
access-list 1 permit 20.20.20.0 log
access-list 1 permit 10.10.10.0 0.0.0.255 log
access-list 1 permit 10.10.30.0 0.0.0.255 log
access-list 1 permit 10.10.129.0 0.0.0.255 log
access-list 1 permit 10.10.110.0 0.0.0.255 log
access-list 1 permit 10.10.120.0 0.0.0.255 log
access-list 1 permit 10.10.150.0 0.0.0.255 log
access-list 1 permit 10.10.151.0 0.0.0.255 log
access-list 1 permit 192.168.1.0 0.0.0.255 log
access-list 1 deny any log
access-list 2 remark Access List to Control BGP-To-OSPF Traffic
access-list 2 permit 3.3.3.3 log
access-list 2 permit 11.11.11.11 log
access-list 2 permit 20.20.20.20 log
access-list 2 permit 25.25.25.25 log
access-list 2 permit 10.10.20.0 0.0.0.255 log
access-list 2 permit 10.10.100.0 0.0.0.255 log
access-list 2 permit 10.10.110.0 0.0.0.255 log
access-list 2 permit 10.10.120.0 0.0.0.255 log
access-list 2 permit 10.10.150.0 0.0.0.255 log
access-list 2 permit 192.168.1.0 0.0.0.255 log
access-list 2 deny any log
!
end
Core-RT#
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!
hostname NRR1
!
interface Loopback0
description "WAN Router Loopback IP Address"
ip address 3.3.3.3 255.255.255.255
!
interface Ethernet0/1
description "Link to D1 - Router 1"
ip address 10.10.100.2 255.255.255.0
!
router bgp 300
bgp router-id 3.3.3.3
bgp log-neighbor-changes
network 3.3.3.3 mask 255.255.255.255
network 10.10.20.0 mask 255.255.255.0
network 10.10.100.0 mask 255.255.255.0
neighbor 10.10.20.2 remote-as 400
neighbor 10.10.20.2 update-source Ethernet1/0
neighbor 10.10.100.1 remote-as 400
neighbor 10.10.100.1 update-source Ethernet0/1
!
end
NRR1#
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