11-4 neighbor ip-address poll-interval interval

11-4 neighbor ip-address poll-interval interval

Syntax Description:

• ip-address ” IP address of the OSPF neighbor. If a secondary address is used on the interface, then the primary address must be used with this command because OSPF will only form an adjacency using the primary address.

• interval ” Poll interval in seconds. The range of values is from 0 “4,294,967,295.

Purpose: If a Hello packet has not been received from a neighbor during the dead interval, the neighbor is declared down. Hello packets will be sent to the neighbor at the rate specified by the poll interval when the neighbor is down. This option does not apply to point-to-multipoint interfaces.

Initial Cisco IOS Software Release: 10.0

Configuration Example: Setting the Poll Interval on an NBMA Network

In Figure 11-7, Routers A and B have formed an OSPF adjacency over the NBMA network. Hello packets will be sent by both routers periodically. The time between Hello packets is determined by the Hello interval. If Router A does not receive a Hello packet from Router B during a period of time determined by the dead interval, Router A will declare Router B down. Router A will continue to send Hello packets to Router B, but at a reduced rate. This reduced rate is the poll interval. The configuration for the routers in Figure 11-7 is shown in the listing that follows .

Figure 11-7. When a Neighbor on an NBMA Network Is Declared Down, Hello Packets Will Be Sent at a Reduced Rate Determined by the Poll Interval

 Router A  interface Loopback0   ip address 1.1.1.1 255.255.255.255   !   interface Serial0/0   bandwidth 64   ip address 10.1.1.1 255.255.255.252   encapsulation frame-relay   frame-relay lmi-type ansi   !   router ospf 1   network 1.1.1.1 0.0.0.0 area 1   network 10.1.1.0 0.0.0.3 area 0   neighbor 10.1.1.2  ________________________________________________________________ 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   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay lmi-type ansi   !   router ospf 1   network 2.2.2.2 0.0.0.0 area 2   network 10.1.1.0 0.0.0.3 area 0  

The value of the poll interval can be viewed using the show ip ospf neighbor detail command.

 rtrA#  show ip ospf neighbor detail  Neighbor 2.2.2.2, interface address 10.1.1.2     In the area 0 via interface Serial0/0     Neighbor priority is 1, State is FULL, 16 state changes     DR is 10.1.1.2 BDR is 10.1.1.1  Poll interval 60  Options 2     Dead timer due in 00:01:42 

Modify the configuration on Router A to change the poll interval to 90.

  router ospf 1   network 1.1.1.1 0.0.0.0 area 1   network 10.1.1.0 0.0.0.3 area 0    neighbor 10.1.1.2 poll-interval 90   

Verification

Verify that Router A is now using a poll interval of 90.

 rtrA#  show ip ospf neighbor detail  Neighbor 2.2.2.2, interface address 10.1.1.2     In the area 0 via interface Serial0/0     Neighbor priority is 0, State is FULL, 17 state changes     DR is 10.1.1.2 BDR is 10.1.1.1  Poll interval 90  Options 2     Dead timer due in 00:01:31 

Troubleshooting

Step 1. The poll-interval option can be applied only to NBMA networks. This option is not allowed on a point-to-multipoint interface.

Step 2. Verify that the OSPF routers have established a FULL adjacency.

Step 3. If the OSPF neighbors have a FULL adjacency, the command poll-interval should work.