Step 1: Verify OSPF Neighbors

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Step 1: Verify OSPF Neighbors
Action

To verify that routers are adjacent and able to exchange OSPF data, enter the following CLI operational mode command:
user@host> show ospf neighbor
Sample Output

The following sample output shows the adjacencies that formed for all routers in Figure 12:
user@R1> show ospf neighbor 
  Address         Interface             State      ID              Pri  Dead
10.1.12.2        so-0/0/0.0             Full      10.0.0.2         128   36  
user@R2> show ospf neighbor 
  Address         Interface             State      ID              Pri  Dead
10.1.23.2        so-0/0/1.0             Full      10.0.0.3         128   32  
10.1.24.2        so-0/0/3.0             Full      10.0.0.4         128   33  
10.1.12.1        so-0/0/0.0             Full      10.0.0.1         128   33  
user@R3> show ospf neighbor    
  Address         Interface             State      ID              Pri  Dead
10.1.34.2        so-0/0/0.0             Full      10.0.0.4         128   36  
10.1.23.1        so-0/0/1.0             Full      10.0.0.2         128   38  
10.1.36.2        so-0/0/3.0             Full      10.0.0.6         128   33 
user@R4> show ospf neighbor 
  Address         Interface             State      ID              Pri  Dead
10.1.34.1        so-0/0/0.0             Full      10.0.0.3         128   31  
10.1.24.1        so-0/0/3.0             Full      10.0.0.2         128   36  
10.1.45.2        so-0/0/2.0             Full      10.0.0.5         128   39  
user@R5> show ospf neighbor 
  Address         Interface             State      ID              Pri  Dead
10.1.45.1        so-0/0/2.0             Full      10.0.0.4         128   35 
user@R6> show ospf neighbor 
  Address         Interface             State      ID              Pri  Dead
10.1.36.1        so-0/0/3.0             Full      10.0.0.3         128   31  
What It Means

The sample output shows that ABR routers R2, R3, and R4 have formed adjacencies with routers in all areas to which they are directly connected. Internal routers (R1, R5, and R6) have formed an adjacency with the other router inside their local area.

Adjacencies are formed after OSPF hello packets are sent and received by neighbors. Adjacencies determine the type of LSAs sent and received, and what topological database updates are sent. When adjacencies are established, pairs of adjacent routers synchronize their topological databases.

Table 33 lists and describes the fields in the show ospf neighbor command.

Table 33: Output Fields for the show ospf neighbor Command

Field

Description

Address

Address of the neighbor.

Interface

Interface through which the neighbor is reachable.

State

State of the neighbor. It can be Attempt, Down, Exchange, ExStart, Full, Init, Loading, or 2 Way.

ID

Router ID of the neighbor.

Pri

Priority of the neighbor to become the designated router. Only used on broadcast networks during designated router elections. By default, set to 128, indicating the highest priority and the most likely router to be elected designated router.

Dead

Number of seconds until the neighbor becomes unreachable.

Field	Description
`Address`	Address of the neighbor.
`Interface`	Interface through which the neighbor is reachable.
`State`	State of the neighbor. It can be `Attempt`, `Down`, `Exchange`, `ExStart`, `Full`, `Init`, `Loading`, or `2 Way`.
`ID`	Router ID of the neighbor.
`Pri`	Priority of the neighbor to become the designated router. Only used on broadcast networks during designated router elections. By default, set to 128, indicating the highest priority and the most likely router to be elected designated router.
`Dead`	Number of seconds until the neighbor becomes unreachable.

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