Open Shortest Path First (OSPF)
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Command Usage
Hello packets are used to inform other routers that the sending router is still
active. Setting the hello interval to a smaller value can reduce the delay in
detecting topological changes, but will increase routing traffic.
Example
ip ospf priority
This command sets the router priority used when determining the designated router
(DR) and backup designated router (BDR) for a network segment. Use the no form
to restore the default value.
Syntax
ip ospf priority priority
no ip ospf priority
priority - Sets the interface priority for this router. (Range: 0-255)
Command Mode
Interface Configuration (VLAN)
Default Setting
1
Command Usage
• A designated router (DR) and backup designated router (BDR) are elected for
each OSPF network segment based on Router Priority. The DR forms an
active adjacency to all other routers in the network segment to exchange
routing topology information. If for any reason the DR fails, the BDR takes
over this role.
• Set the priority to zero to prevent a router from being elected as a DR or BDR.
If set to any value other than zero, the router with the highest priority will
become the DR and the router with the next highest priority becomes the
BDR. If two or more routers are tied with the same highest priority, the router
with the higher ID will be elected.
• If a DR already exists for an area when this interface comes up, the new router
will accept the current DR regardless of its own priority. The DR will not
change until the next time the election process is initiated.
• Configure router priority for multi-access networks only and not for
point-to-point networks.
Example
Console(config)#interface vlan 1
Console(config-if)#ip ospf hello-interval 5
Console(config-if)#
Console(config)#interface vlan 1
Console(config-if)#ip ospf priority 5
Console(config-if)#
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