Hello,
Problem
For some reasons, e.g. misconfiguration in Ethernet VLANs, etc link between
Router-X and Router-2 (it also can be Router-1) will become broken.
There is no direct LSA exchange between Router-X and Router-2
(OSPF neighborhood became ATTEMPT/DROTHER).
Router-X interface that points to Router-2 is still up and Router-2 interface that points to Router-X is still UP too.
But, Router-2 receives routes to Router-X from OSPF cloud and that route points to interface that point directly to Router-X.
This route is redistributed to Router-2 from Router-X via link to Router-X - Router-1.
For GRE tunnels I can prevent this with keepalives. But how can I prevent Router-X to redistribute route to the broken interface?
(net cloud)=area 0=[ROUTER-1]=area 10 nssa=[ROUTER-X]=area 10 nssa=+
] ]
area 0=============================[ROUTER-2]====area 10 nssa=====+
Scheme description
Router-X has connection to Router-1 and Router-2 via Ethernet links.
Network cloud exists behind the routers Router-1 and Router-2.
These routers are not directly connected but belong to area 0 and exchange LSAs.
Router configs
====Router-X====
interface FastEthernet0/0.640
description **** LINK TO ROUTER-2 ****
bandwidth 1000
encapsulation dot1Q 640
ip address 172.20.0.6 255.255.255.252
ip ospf message-digest-key XXXXXX
ip ospf network non-broadcast
no snmp trap link-status
no cdp enable
end
interface FastEthernet0/1.841
description **** LINK TO ROUTER-1 ****
bandwidth 4000
encapsulation dot1Q 841
ip address 172.24.1.5 255.255.255.252
ip ospf message-digest-key XXXXX
ip ospf network non-broadcast
no snmp trap link-status
end
router ospf 200
router-id 10.255.255.18
log-adjacency-changes
area 10 authentication message-digest
area 10 nssa
redistribute connected subnets
redistribute static subnets route-map STATIC_ FILTER
passive-interface default
no passive-interface FastEthernet0/0.640
no passive-interface FastEthernet0/1.244
network 172.20.0.4 0.0.0.3 area 10
network 172.24.1.4 0.0.0.3 area 10
neighbor 172.20.0.5
neighbor 172.24.1.6
====Router-1====
interface GigabitEthernet0/1.841
description **** LINK TO ROUTER-X ****
bandwidth 4000
encapsulation dot1Q 841
ip address 172.24.1.6 255.255.255.252
ip ospf network non-broadcast
no snmp trap link-status
end
router ospf 200
router-id 10.255.255.1
log-adjacency-changes
auto-cost reference-bandwidth 1000
area 0 authentication message-digest
area 10 authentication message-digest
area 10 nssa default-information-originate
redistribute connected subnets route-map CONNECTED_FILTER
redistribute static subnets route-map STATIC_FILTER
passive-interface default
no passive-interface GigabitEthernet0/1.841
no passive-interface GigabitEthernet0/0.1616
no passive-interface GigabitEthernet0/1
no passive-interface GigabitEthernet0/1.359
no passive-interface GigabitEthernet0/1.404
network 172.24.1.4 0.0.0.3 area 10
neighbor 172.24.1.5
====Router-2====
interface FastEthernet0/0.640
description **** LINK TO ROUTER-X ****
bandwidth 1000
encapsulation dot1Q 640
ip address 172.20.0.5 255.255.255.252
ip ospf message-digest-key XXXX
ip ospf network non-broadcast
no snmp trap link-status
no cdp enable
end
router ospf 200
router-id 10.255.255.2
log-adjacency-changes
area 0 authentication message-digest
area 10 authentication message-digest
area 10 nssa default-information-originate
redistribute connected subnets route-map CONNECTED_ FILTER
redistribute static subnets route-map STATIC_ FILTER
network 172.20.0.0 0.0.0.3 area 3
network 172.22.0.56 0.0.0.3 area 0
network 172.22.2.4 0.0.0.3 area 0
network 172.22.2.8 0.0.0.3 area 0
neighbor 172.22.2.10
neighbor 172.22.0.58
neighbor 172.20.0.6
