Cisco OSPF Command and Configuration Handbook (paperback)

2-22 area transit-area-id virtual-link router-id transmit-delay seconds

Syntax Description:

• transit-area-id ” The OSPF area ID of the area connecting the two ABRs that the virtual link will cross. This value can be entered as a decimal number in the range of 0 to 4,294,967,295 or in IP address form in the range 0.0.0.0 to 255.255.255.255. The transit area cannot be a stub area.

• router-id ” OSPF router ID of the router at the remote end of the virtual link.

• seconds ” The range of values is 1 “8192 seconds. The default value is 1 second.

Purpose: When an LSA is created, the router will set the LS age field to 0. The transmit delay value is added to the age field of the LSA. This initial value represents the time delay of propagating the LSA over the virtual link.

Initial Cisco IOS Software Release: 10.0

Configuration Example: Modifying the Transmit Delay Value for a Virtual Link

Configure the network in Figure 2-22 and set the transmit delay value to 2 seconds.

Router A interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Serial0/1 ip address 10.1.1.1 255.255.255.252 clockrate 64000 ! router ospf 1 network 10.1.1.0 0.0.0.3 area 0 network 1.1.1.1 0.0.0.0 area 0 _______________________________________________________________________ Router B interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Serial0 ip address 10.1.1.2 255.255.255.252 ! interface Serial1 ip address 10.1.1.5 255.255.255.252 clockrate 64000 ! router ospf 1 area 1 virtual-link 3.3.3.3 transmit-delay 2 network 10.1.1.0 0.0.0.3 area 0 network 2.2.2.2 0.0.0.0 area 0 network 10.1.1.4 0.0.0.3 area 1 _______________________________________________________________________ Router C interface Loopback0 ip address 3.3.3.3 255.255.255.255 ! interface Serial0 ip address 10.1.1.6 255.255.255.252 ! router ospf 1 area 1 virtual-link 2.2.2.2 transmit-delay 2 network 3.3.3.3 0.0.0.0 area 2 network 10.1.1.4 0.0.0.3 area 1

Verification

Verify that the transmit delay value has been modified, that the virtual link is active, and that all OSPF routes are being exchanged.

rtrB# show ip ospf virtual-links Virtual Link OSPF_VL0 to router 3.3.3.3 is up Run as demand circuit DoNotAge LSA allowed. Transit area 1, via interface Serial1, Cost of using 64 Transmit Delay is 2 sec , State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 6 Hello due in 00:00:01 Adjacency State FULL (Hello suppressed) _______________________________________________________________________ rtrC# show ip ospf virtual-links Virtual Link OSPF_VL7 to router 2.2.2.2 is up Run as demand circuit DoNotAge LSA allowed. Transit area 1, via interface Serial0, Cost of using 64 Transmit Delay is 2 sec , State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:03 Adjacency State FULL (Hello suppressed) rtrC# show 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, * - candidate default U - per-user static route, o - ODR Gateway of last resort is not set 1.0.0.0/32 is subnetted, 1 subnets O 1.1.1.1 [110/129] via 10.1.1.5, 00:02:25, Serial0 2.0.0.0/32 is subnetted, 1 subnets O 2.2.2.2 [110/65] via 10.1.1.5, 00:02:26, Serial0 3.0.0.0/24 is subnetted, 1 subnets C 3.3.3.0 is directly connected, Loopback0 10.0.0.0/30 is subnetted, 2 subnets O 10.1.1.0 [110/128] via 10.1.1.5, 00:02:26, Serial0 C 10.1.1.4 is directly connected, Serial0

Troubleshooting

Step 1. Verify that there is a neighbor relationship between the OSPF routers by using the show ip ospf neighbor command.

Step 2. Verify that the transit area ID used in the area virtual-link command is the proper area.

Step 3. Verify that the router IDs used in the area virtual-link are correct.

Step 4. Verify that the desired transmit delay value has been configured by using the command show ip ospf virtual-links.