Nortel Switched Firewall 2.3.3 User’s Guide and Command Reference
104
Open Shortest Path First
213455-L, October 2005
Interface cost
The OSPF link-state algorithm (Dijkstra’s algorithm) places each routing device at the root of
a tree and determines the cumulative
cost
required to reach each destination. Usually, the cost
is inversely proportional to the bandwidth of the interface. Low cost indicates high bandwidth.
You can manually enter the cost for the output route with the following commands:
Electing the designated router and backup
In any area with more than two routing devices, a Designated Router (DR) is elected as the
central contact for database exchanges among neighbors, and a Backup Designated Router
(BDR) is elected in case the DR fails.
DR and BDR elections are made through the hello process. The election can be influenced by
assigning a priority value to the OSPF interfaces. The commands are as follows:
A priority value of 255 is the highest, and 1 is the lowest. A priority value of 0 specifies that
the interface cannot be used as a DR or BDR. In case of a tie, the routing device with the
lowest router ID wins.
Router ID
Routing devices in OSPF areas are identified by a router ID. The router ID is expressed in IP
address format. The IP address of the router ID is not required to be included in any IP
interface range or in any OSPF area.
The router ID can be configured in one of the following two ways:
Statically—Use the following command to manually configure the router ID:
Dynamically—OSPF protocol configures the lowest IP interface IP address as the router
ID. This is the default. To use a dynamic router ID after having set it statically, set the
router ID to 0.0.0.0 and reboot the Nortel Switched Firewall.
>> #
/cfg/net/ospf/if
<interface number>
>> #
cost
<cost value (1-65535)>
>> #
/cfg/net/ospf/if
<interface number>
>> #
prio
<priority value (0-255)>
>> #
/cfg/net/ospf/rtrid1
<IP address>