Summary:
1. Ensure "Shoe" does not form OSPF neighbors on its LAN network (for security reason)
2. Adjust the Hello Timer on the "Sock" WAN interface to send Hello message 1/sec so you can make OSPF recover faster.
3. Create loopback interfaces in such a way that Router IDs are pingable from any router
1. Ensure "Shoe" does not form OSPF neighbors on its LAN network
Shoe:
Method 1.
router ospf 1
passive-interface fa 0/0 !------------------ this disables the hello message, but it still advertises its network to everybody else
#Test:
Shoe(config-router)#do sh ip ospf interface
FastEthernet0/0 is up, line protocol is up
Internet Address 10.1.3.1/24, Area 0
Process ID 1, Router ID 4.4.4.4, Network Type BROADCAST, Cost: 100
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 4.4.4.4, Interface address 10.1.3.1
No backup designated router on this network
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
No Hellos (Passive interface) !-------------------------------------------------- here you see "no hello"
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 0, maximum is 0
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 0, Adjacent neighbor count is 0
Suppress hello for 0 neighbor(s)
Serial1/0 is up, line protocol is up
Internet Address 10.1.2.2/24, Area 0
Process ID 1, Router ID 4.4.4.4, Network Type POINT_TO_POINT, Cost: 6476
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:02 !------------------------------------- serial interface still has hello message
Supports Link-local Signaling (LLS)
Index 2/2, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 1
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 3.3.3.3
Suppress hello for 0 neighbor(s)
Shoe(config-router)#
Method 2. (prefered)
router ospf 1
passive-interface default !------------------------- turn off ospf on all interfaces
no passive-interface serial 1/0 !------------------- only enable the interface that needs to run ospf
2. Adjust the Hello Timer on the "Sock" WAN interface to send Hello message 1/sec so you can make OSPF recover faster.
Sock:
Sock#sh ip ospf interface
FastEthernet0/0 is up, line protocol is up
Internet Address 10.1.1.3/24, Area 0
Process ID 1, Router ID 3.3.3.3, Network Type BROADCAST, Cost: 1000
Transmit Delay is 1 sec, State DROTHER, Priority 1
Designated Router (ID) 1.1.1.1, Interface address 10.1.1.1
Backup Designated router (ID) 2.2.2.2, Interface address 10.1.1.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
oob-resync timeout 40
Hello due in 00:00:05
Supports Link-local Signaling (LLS)
Index 2/2, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 0, maximum is 1
Last flood scan time is 0 msec, maximum is 4 msec
Neighbor Count is 2, Adjacent neighbor count is 2
Adjacent with neighbor 1.1.1.1 (Designated Router)
Adjacent with neighbor 2.2.2.2 (Backup Designated Router)
Suppress hello for 0 neighbor(s)
Serial1/0 is up, line protocol is up
Internet Address 10.1.2.1/24, Area 0
Process ID 1, Router ID 3.3.3.3, Network Type POINT_TO_POINT, Cost: 6476
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 !----------------------------- default is 10 sec, and wait 40 seconds
oob-resync timeout 40
Hello due in 00:00:00
Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Next 0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 2
Last flood scan time is 0 msec, maximum is 4 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 4.4.4.4
Suppress hello for 0 neighbor(s)
Sock#
int s1/0
ip ospf hello-interval 1
#NOTE: you have to do the same on its neighbor router because hello interval has to be matched on both routers
*Mar 3 00:22:15.115: %OSPF-5-ADJCHG: Process 1, Nbr 4.4.4.4 on Serial1/0 from FULL to DOWN, Neighbor Down: Dead timer expired
Sock#sh ip ospf neighbor !------------------------------------------------------------------------------- You no longer see 4.4.4.4 (Shoe)
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 10 FULL/DR 00:00:39 10.1.1.1 FastEthernet0/0
2.2.2.2 1 FULL/BDR 00:00:36 10.1.1.2 FastEthernet0/0
Sock#
Shoe:
int s1/0
ip ospf hello-interval 1
#Test:
Sock#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 10 FULL/DR 00:00:35 10.1.1.1 FastEthernet0/0
2.2.2.2 1 FULL/BDR 00:00:31 10.1.1.2 FastEthernet0/0
4.4.4.4 0 FULL/ - 00:00:03 10.1.2.2 Serial1/0 !------------------------------------now you see Shoe as the neighbor again
Sock#
3. Create loopback interfaces in such a way that Router IDs are pingable from any router
Shoe:
int loopback 0
ip address 4.4.4.4 255.255.255.255
router ospf 1
network 4.4.4.4 0.0.0.0 area 0
#Test:
Tie#show ip route
Codes: 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
Gateway of last resort is not set
4.0.0.0/32 is subnetted, 1 subnets
O 4.4.4.4 [110/7477] via 10.1.1.3, 00:00:45, FastEthernet0/0 !----------------------------------- now you see the route from Tie
10.0.0.0/24 is subnetted, 3 subnets
O 10.1.3.0 [110/7576] via 10.1.1.3, 00:00:45, FastEthernet0/0
O 10.1.2.0 [110/7476] via 10.1.1.3, 00:00:45, FastEthernet0/0
C 10.1.1.0 is directly connected, FastEthernet0/0
Tie#
Tie#ping 4.4.4.4 !-----------------------------------------------------------------------------------and you can ping Shoe's loopback from Tie
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 52/61/84 ms
Tie#
Sock:
int loopback 0
ip address 3.3.3.3 255.255.255.255
router ospf 1
network 3.3.3.3 0.0.0.0 area 0
Belt:
int loopback 0
ip address 2.2.2.2 255.255.255.255
router ospf 1
network 2.2.2.2 0.0.0.0 area 0
Tie:
int loopback 0
ip address 1.1.1.1 255.255.255.255
router ospf 1
network 1.1.1.1 0.0.0.0 area 0
-Yu