3Com Switch 7750 Configuration Guide

OSPF Route Control 313
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■ After an interface has been configured with a new network type, the original
network type of the interface is removed automatically.
■ Note that, neighboring relationship can be established between two interfaces
configured as broadcast, NBMA, or P2MP only if the interfaces are on the same
network segment.
Setting an NBMA
Neighbor
Some special configurations need to be done on an NBMA network. Since an
NBMA interface cannot discover the adjacent router by broadcasting Hello
packets, you must manually specify the IP address of the adjacent router for the
interface and whether the adjacent router has the right to vote.
Setting the DR Priority
on an OSPF Interface
You can control the DR/BDR election on a broadcast or NBMA network by
configuring the DR priorities of interfaces.
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The DR priorities configured by the ospf dr-priority command and the peer
command have different purpose
■ The priority set with the ospf dr-priority command is used for actual DR
election.
■ The priority set with the peer command is used to indicate if a neighbor has
the right to vote. If you specify the priority to 0 when configuring a neighbor,
the local router will believe that the neighbor has no right to vote and sends no
Hello packet to it. This configuration can reduce the number of Hello packets
on the network during the election of DR and BDR. However, if the local router
is already a DR or BDR, it will send Hello packets to the neighbor whose DR
priority is 0 to establish the neighboring relationship.
OSPF Route Control Perform the following configurations to control the advertisement and reception
of the routing information discovered by OSPF and import routing information
discovered by other protocols.
Table 234 Set NBMA neighbor
Operation Command Description
Enter system view system-view -
Enter OSPF view ospf [ process-id
[ router-id router-id ]]
Required
Set an NBMA neighbor peer ip-address
[ dr-priority
dr-priority-value ]
Required
By default, the priority for
the neighbor of an NBMA
interface is 1.
Table 235 Set the DR priority on an OSPF interface
Operation Command Description
Enter system view system-view -
Enter interface view interface interface-type
interface-number
Required
Set the DR priority on the
OSPF interface
ospf dr-priority priority Optional
The default DR priority is
1.