3Com 8807 Configuration Manual page 320

320 C 31: OSPF C
HAPTER
Setting OSPF Route
Preference
Configuring OSPF Timers
ONFIGURATION
If the local router works as an area border router (ABR) and a router in the NSSA,
this command summarizes Type-5 LSAs transformed from Type-7 LSAs. If the
router is not the router in the NSSA, the summarization is disabled.
Since maybe multiple dynamic routing protocols are running on one router
concurrently, the problem of route sharing and selection between various routing
protocols occurs. The system sets a preference for each routing protocol, which
will be used in tie-breaking in case different protocols discover the same route.
Perform the following configuration in OSPF view.
Table 285 Set OSPF route preference
Operation
Configure a preference for OSPF for
comparing with the other routing protocols
Restore the default protocol preference
By default, the OSPF preference is 10, and that of the imported external routing
protocol is 150.
Setting the interval for Hello packet transmission
Hello packets are a kind of most frequently used packets, which are periodically
sent to the adjacent router for discovering and maintaining the adjacency, and for
electing DR and BDR. The user can set the Hello timer.
According to RFC2328, the consistency of Hello intervals between network
neighbors should be kept. The Hello interval value is in inverse proportion to the
route convergence rate and network load.
Perform the following configuration in interface view.
Table 286 Set the Hello interval
Operation
Set the hello interval of the interface
Restore the default hello interval of the interface
Restore the default poll interval
By default, p2p and broadcast interfaces send Hello packets every 10 seconds, and
p2mp interfaces send Hello packets every 30 seconds.
Setting a dead timer for the neighboring routers
The dead timer of neighboring routers refers to the interval in which a router will
regard the neighboring router as dead if no Hello packet is received from it. The
user can set a dead timer for the neighboring routers.
Perform the following configuration in interface view.
Command
preference [ ase ] preference
undo preference [ ase ]
Command
ospf timer hello seconds
undo ospf timer hello
undo ospf timer poll