show ip ospf interface [type-number]
This command is used to show how OSPF has been configured on an interface level, as well as how it is working at the interface. This level of detail is excellent for troubleshooting configuration errors.
Example 5-8 shows the output of this command. Table 5-10 explains how to read this information.
Example 5-8 show ip ospf interface [type-number] Output
SanJose#show ip ospf interface fastethernet1/0
FastEthernet1/0 is up, line protocol is up Internet Address 140.100.17.129/28, Area 3
Process ID 100, Router ID 140.100.32.10, Network Type BROADCAST, Cost: 1 Transmit Delay is 1 sec, State DR, Priority 100
Designated Router (ID) 140.100.32.10, Interface address 140.100.17.129 Backup Designated router (ID) 140.100.23.1, Interface address 140.100.17.130 Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:06 Neighbor Count is 3, Adjacent neighbor count is 2 Adjacent with neighbor 140.100.17.132 Adjacent with neighbor 140.100.17.131
Adjacent with neighbor 140.100.23.1 (Backup Designated Router) Suppress hello for 0 neighbor(s)
Field |
Explanation |
FastEthernet1/0 is up, line protocol |
This should be seen as two statements. The first half of the |
is up |
sentence indicates that the physical line is operational. This |
meaning differs with the type of interface; for Ethernet, it | |
indicates the presence of the transceiver. The second portion | |
of the sentence indicates that the data link layer is working. | |
Internet Address 140.100.17.129/28, |
The IP address and mask configured on the interface. |
Area 3 | |
Area 3 |
The OSPF area for which the interface is configured. |
Process ID 100, Router ID |
The autonomous system number, which is in fact the OSPF |
140.100.32.10 |
process ID. |
The router ID that will be advertised in the LSA updates. | |
Network Type BROADCAST |
The type of network that the interface is connected to, which |
indicates how neighbors are found and adjacencies are | |
formed. | |
Cost: 1 |
The metric cost of the link, which, although not stated, was |
probably dynamically chosen using the Cisco defaults. | |
Transmit Delay is 1 sec |
The anticipated time taken to send an update to the neighbor. |
The default is 1 second. | |
State DR |
The state of the link in reference to establishing adjacencies. |
This field is extremely useful in troubleshooting. Here are the | |
states in order: | |
DOWN—Heard from no one. | |
ATTEMPT—Sent a hello on an NBMA, but haven't heard |
back.
INIT—Heard a hello, but have not achieved neighbor status.
TWO-WAY—Established full neighbor relationship; saw itself in the neighbor's hello table.
EXSTART—Starting up the link for exchanging DDPs.
EXCHANGE—Sending DDPs to other router.
LOADING—Building the database and LSAs from the DDPs.
FULL—Established adjacency. DR—Is the designated router for this LAN.
continues
Field |
Explanation |
Priority 100 |
The priority is sent in the Hello protocol and is used to |
determine the election of the designated router and the | |
backup designated router. The value of 1 means that the | |
router is prepared to be elected. If every other router has the | |
priority of 1, the highest router ID will select the routers. | |
Designated Router (ID) |
The address of the elected designated router. Note that the ID |
140.100.32.10, Interface address |
and the interface ID differ. This is a useful field for |
140.100.17.129 |
troubleshooting misconfiguration. |
Backup Designated router (ID) |
The address of the backup designated router. Note that both |
140.100.23.1, Interface address |
the ID and the interface are given, and they differ. |
140.100.17.130 | |
Timer intervals configured, Hello 10, |
It is possible to change these timers and sometimes necessary |
Dead 40, Wait 40, Retransmit 5 |
if connecting to another vendor's equipment that has |
different defaults. These timers should be consistent | |
throughout the area. The defaults are as follows: | |
Hello: 10 | |
Dead: 40 | |
Wait: 40 | |
Retransmit: 5 | |
Hello due in 00:00:06 |
When the next hello packet is due to be sent out of the |
interface. | |
Neighbor Count is 3, Adjacent |
The number of routers that have neighbor relationships. |
neighbor count is 2 |
Note that the number of routers with which adjacency is |
established is less than the number of neighbors. This is | |
because there is a designated router and a backup designated | |
router, whose responsibility it is to maintain the adjacencies | |
with all routers on the LAN. |
Adjacent with neighbor 140.100.23.1 The router ID of the adjacent router, which is the backup (Backup Designated Router) designated router in this case.
Was this article helpful?
Post a comment