Operation Manual - Routing Protocol
Quidway S3500 Series Ethernet Switches Chapter 4 OSPF Configuration
Huawei Technologies Proprietary
4-9
the concept of BDR. In fact, BDR is a backup for DR. DR and BDR are elected in the
meantime. The adjacencies are also established between the BDR and all the routers
on the segment, and routing information is also exchanged between them. When the
DR fails, the BDR will become the DR instantly. Since no re-election is needed and the
adjacencies have already been established, the process is very short. But in this case,
a new BDR should be elected. Although it will also take a quite long period of time, it will
not exert any influence upon the route calculation.
But please note:
z The DR on the network is not necessarily the router with the highest priority.
Likewise, the BDR is not necessarily the router with the second highest priority. If a
new router is added after DR and BDR election, it is impossible for the router to
become the DR even if it has the highest priority.
z DR is based on the router interface in a certain segment. Maybe a router is a DR
on one interface, but can be a BDR or DROther on the other interface.
z DR election is only required for the broadcast or NBMA interfaces. For the p2p or
p2mp interfaces, DR election is not required.
Perform the following configuration in Interface view:
Table 4-7 Setting the Interface Priority for DR Election
Operation Command
Configure the interface with a priority for
DR election
ospf dr-priority priority_num
Restore the default interface priority
undo ospf dr-priority
By default, the priority of the Interface is 1 in the DR election. The value can be taken
from 0 to 255.
4.2.8 Setting the Peer
For a NBMA network, some special configurations are required. Since an NBMA
interface on the network cannot discover the adjacent router through broadcasting the
Hello packets, you must manually specify an IP address for the adjacent router for the
interface, and whether the adjacent router is eligible for election. This can be done by
configuring the peer ip-address command.
Perform the following configuration in OSPF view.
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