3com 5500-ei pwr Installation Instruction
4-12
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DR is based on the router interfaces in a certain segment. A router may be a DR on an interface
and a BDR or DR Other on another interface.
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The priority of a router affects the DR and BDR election. However, it has no effect on the election
after the DR and BDR election ends. A new priority assigned to the router takes effect at the time of
next DR and BDR election.
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If a new router is added after DR and BDR election, the router does not become the DR
immediately even if it has the highest DR priority.
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The DR on a network segment is unnecessarily the router with the highest priority. Likewise, the
BDR is unnecessarily the router with the second highest priority.
OSPF Features
The switches support the following OSPF features:
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Stub area: Stub area is defined to reduce the cost for the routers in the area to receive ASE routes.
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NSSA: NSSA is defined to remove the limit on the topology in a Stub area.
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OSPF multi-process: Multiple OSPF processes can be run on a router.
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Sharing discovered routing information with other dynamic routing protocols: At present, OSPF
supports importing the routes of other dynamic routing protocols (such as RIP), and static routes as
OSPF external routes into the AS to which the router belongs. In addition, OSPF supports
advertising the routing information it discovered to other routing protocols.
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Packet authentication: OSPF supports the authentication of the packets between neighboring
routers in the same area by using one of the two methods: plain text authentication and MD5
authentication.
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Flexible configuration of router interface parameters: For a router interface, you can configure the
following OSPF parameters: output cost, Hello interval, retransmission interval, interface
transmission delay, route priority, dead time for a neighboring router, and packet authentication
mode and authentication key.
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Virtual link: Virtual links can be configured.
OSPF Configuration Task List
Complete the following tasks to configure OSPF:
Task
Remarks
Required
Optional
Optional
Optional
Optional
Optional
Optional
Optional