Configuring OSPF Static Neighbors
There will be some scenarios where you will need to build static OSPF Neighbors such as for NBMA relationships or for network security hardening. This lab will discuss and demonstrate the configuration and verification o.
Real World Application & Core Knowledge
In lab 9-1 when you configured OSPF initially you had to change the frame relay hub and spoke network type to broadcast to ensure the neighbor relationships formed. However the default network type for OSPF on a serial interface with frame relay encapsulation is non-broadcast. With this in mind you must configure static neighbors to ensure OSPF can form a neighbor relationship, this is due to frame relay trading multicast as pseudo-broadcast and if a frame relay PVC (Permanent Virtual Circuit) is not broadcast capable then multicast would not traverse the PVC.
In this lab you will revert the routers serial interfaces in the hub-and-spoke topology back to its default, non-broadcast and configure a static neighbor statement on R1. The static neighbor statement only needs to be configured on the hub however its best to configure it on both hub and spokes to ensure initialization of neighbor negotiation.
You can manually specify the network type as non-broadcast on the interface of you can negate the current OSPF network type on the interfaces thus reverting it back to its default; either way will suffice for this lab.
Familiarize yourself with the following new command(s);
| Command | Description |
|---|---|
| no ip ospf network | Executed in interface configuration mode to revert the OSPF network type back to its default for that specified interface. |
| ip ospf network non-broadcast | Executed in interface configuration mode to configure the specified interface OSPF network type to non-broadcast; this mode requires static neighbor statements and will form a DR/BDR relationship. |
The following logical topology shown below is used in labs found through out Section 9 – Configuring OSPF;
Lab Prerequisites
- If you are using GNS3 than load the Free CCNA Workbook GNS3 topology than start devices; R1, R2, R3, R4, R5 and SW1.
- Establish a console session with devices R1, R2, R3, R4, R5 and SW1 than load the initial configurations provided below by copying the config from the textbox and pasting it into the respected routers console.
Lab Objectives
- Revert the OSPF interface type back its default on R1, R2, R4 and R5’s frame relay hub and spoke interfaces.
- Configure static neighbor statements on R1 pointing to R2, R4 and R5.
- Verify that the neighbor relationships form using the show ip ospf neighbor command.
Lab Instruction
Objective 1. – Revert the OSPF interface type back its default on R1, R2, R4 and R5’s frame relay hub and spoke interfaces.
R1>enable R1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R1(config)#interface Serial0/0 R1(config-if)#no ip ospf network R1(config-if)#end R1# %OSPF-5-ADJCHG: Process 1, Nbr 10.90.20.1 on Serial0/0 from FULL to DOWN, Neighbor Down: Interface down or detached %OSPF-5-ADJCHG: Process 1, Nbr 10.90.40.1 on Serial0/0 from FULL to DOWN, Neighbor Down: Interface down or detached %OSPF-5-ADJCHG: Process 1, Nbr 10.90.50.1 on Serial0/0 from FULL to DOWN, Neighbor Down: Interface down or detached R1# *Jul 8 20:19:16.767: %SYS-5-CONFIG_I: Configured from console by console R1#
R2>enable R2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R2(config)#interface Serial0/0 R2(config-if)#no ip ospf network R2(config-if)#end R2#
R4>enable R4#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R4(config)#interface Serial0/0 R4(config-if)#no ip ospf network R4(config-if)#end R4#
R5>enable R5#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R5(config)#interface Serial0/0 R5(config-if)#no ip ospf network R5(config-if)#end R5#
Objective 2. – Configure static neighbor statements on R1 pointing to R2, R4 and R5.
R1#configure terminal Enter configuration commands, one per line. End with CNTL/Z. R1(config)#router ospf 1 R1(config-router)#neighbor 10.90.245.2 R1(config-router)#neighbor 10.90.245.4 R1(config-router)#neighbor 10.90.245.5 R1(config-router)#end R1# %OSPF-5-ADJCHG: Process 1, Nbr 10.90.20.1 on Serial0/0 from LOADING to FULL, Loading Done %OSPF-5-ADJCHG: Process 1, Nbr 10.90.40.1 on Serial0/0 from LOADING to FULL, Loading Done %OSPF-5-ADJCHG: Process 1, Nbr 10.90.50.1 on Serial0/0 from LOADING to FULL, Loading Done R1#
Objective 3. – Verify that the neighbor relationships form using the show ip ospf neighbor command.
R1#show ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.90.20.1 0 FULL/DROTHER 00:01:51 10.90.245.2 Serial0/0
10.90.40.1 0 FULL/DROTHER 00:01:35 10.90.245.4 Serial0/0
10.90.50.1 0 FULL/DROTHER 00:01:45 10.90.245.5 Serial0/0
R1#
