Configuring OSPF Interface Parameters

Configuration of the OSPF Interface parameters are described in the following sub-sections. The interface parameters are configured in the Interface Configuration mode.

To enable OSPF, execute the following commands.

Type the following:

  • Enter the Global Configuration Mode in ISS1.
iS5comm# configure terminal
  • Enable OSPF globally in the switch ISS1.
iS5comm(config)# router ospf
  • Enable OSPF over the VLAN interface and associate the interface with an OSPF area. VLAN interfaces VLAN1 and VLAN10 are created as a part of the prerequisite configuration.
iS5comm(config-router)# network 10.4.0.1 area 0.0.0.0
iS5comm(config-router)# network 10.10.2.1 area 0.0.0.6
iS5comm(config-router)# exit
Note:

When OSPF routing is enabled using the “network” command, an established session is properly mapped with the interface only if the interface administrative status is up. This is because to enable OSPF in an interface, both IP address and interface index are used.

  • Enter the Interface Configuration Mode.
iS5comm(config)# interface vlan 1
iS5comm(config-if)#
Parent topic: Configuring OSPF

Configuring OSPF Interface Priority

Configuring LSA (link-state advertisement) retransmission Interval specifies the time interval between the LSA retransmissions.

  1. Execute the following command to configure the VLAN 1 retransmit- interval as 10 seconds.

    Type the following:

    iS5comm(config-if)# ip ospf ip ospf retransmit-interval 10
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type BROADCAST, Cost 1
    Transmit Delay is 1 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
    Note:

    A priority value of 0 signifies that the router is not eligible to become the designated router on a particular network.

    Note:

    The default interface priority value is 1.

  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf priority

Configuring LSA Retransmission Interval

Configuring OSPF Interface Priority sets the interface priority of the router, which helps to determine the designated router for the link connected to the interface.

  1. Execute the following command to configure the VLAN 1 interface priority as 10.

    Type the following:

    iS5comm(config-if)# ip ospf priority 10
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type BROADCAST, Cost 1
    Transmit Delay is 1 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 10
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf retransmit-interval

Configuring Link State Update Packet Transmission Delay

Configuring link state update packet transmission delay sets the estimated time required to transmit a link state update packet on the interface.

  1. Execute the following command to configure the VLAN 1 transmission delay.

    Type the following:

    iS5comm(config-if)# ip ospf transmit-delay 5
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type BROADCAST, Cost 1
    Transmit Delay is 5 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf transmit-delay

Configuring Hello-Interval

Configuring “hello interval” specifies the interval between hello packets sent on the interface.

  1. Execute the following command to configure the VLAN 1 hello interval as 40 seconds.

    Type the following:

    iS5comm(config-if)# ip ospf hello-interval 40
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type BROADCAST, Cost 1
    Transmit Delay is 1 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 40, Dead 40, Wait 40, Retransmit 5
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf hello-interval

Configuring OSPF Dead-Interval

Configuring dead-interval sets the interval at which hello packets must not be seen before the neighbors declare the router down.

  1. Execute the following command to configure the VLAN 1 dead-interval as 120 seconds.

    Type the following:

    iS5comm(config-if)# ip ospf dead-interval 120
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type BROADCAST, Cost 1
    Transmit Delay is 1 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 10, Dead 120, Wait 40, Retransmit 5
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf dead-interval

Configuring Network Type

The OSPF network type can be broadcast, non-broadcast, point-to-multipoint or point-to-point. The default type is broadcast. The OSPF network type can be configured to a type other than the default for a given media.

  1. Execute the following command to configure the VLAN 1 network type as point-to-point.

    Type the following:

    iS5comm(config-if)# ip ospf network point-to-point
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type PointToPoint, Cost 1
    Transmit Delay is 1 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf network

Configuring Demand Circuit

When an OSPF link is configured as demand circuit, OSPF Hellos are suppressed and periodic LSA refreshes are not flooded over the link. These packets bring up the link only when they are exchanged for the first time, or when a change occurs in the information they contain. This allows the underlying Data Link Layer to be closed when the network topology is stable.

  1. Execute the following command to configure the VLAN 1 as OSPF demand circuit.

    Type the following:

    iS5comm(config-if)# ip ospf demand-circuit
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type BROADCAST, Cost 1 
    Configured as demand circuit. 
    Run as demand
    Transmit Delay is 1 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf demand-circuit

Configuring Interface Cost

Configuring Interface Cost specifies the cost of sending a packet on an interface.

  1. Execute the following command to configure the VLAN 1 interface cost as 20.

    Type the following:

    iS5comm(config-if)# ip ospf cost 20
  2. View the configuration details by executing the following show command.

    Type the following:

    iS5comm# show ip ospf interface vlan 1
    vlan1 is line protocol is up 
    Internet Address 10.4.0.1, Mask 255.255.0.0, Area 0.0.0.0
    AS 1, Router ID 10.10.2.1, Network Type BROADCAST, Cost 20
    Transmit Delay is 1 sec, State 4, Priority 10 
    Designated RouterId 10.10.2.1, Interface address 10.4.0.1
    No backup designated router on this network
    Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 4 sec
    Neighbor Count is 0, Adjacent neighbor count is 0
  3. Restore the default value of the OSPF Interface by executing the following command.

    Type the following:

    iS5comm(config-if)# no ip ospf cost