Configuration Prerequisites; Configuring Ospf Timers - 3Com 5500-EI PWR Install Manual

By Adjusting SPF calculation interval, you can mitigate resource consumption caused by frequent
network changes.
In a network with high security requirements, you can enable OSPF authentication to enhance
OSPF network security.
In addition, OSPF supports network management. You can configure the binding of the OSPF MIB
with an OSPF process and configure the Trap message transmission and logging functions.

Configuration Prerequisites

Before adjusting and optimizing an OSPF network, perform the following tasks:
Configuring the network layer addresses of interfaces so that the adjacent nodes are reachable to
each other at the network layer
Configuring basic OSPF functions

Configuring OSPF Timers

The Hello intervals for OSPF neighbors must be consistent. The value of Hello interval is in inverse
proportion to route convergence speed and network load.
The dead time on an interface must be at least four times of the Hello interval on the same interface.
After a router sends an LSA to a neighbor, it waits for an acknowledgement packet from the neighbor. If
the router receives no acknowledgement packet from the neighbor within the retransmission interval, it
retransmits the LSA to the neighbor.
Follow these steps to configure OSPF timers:
To do...
Enter system view
Enter interface view
Configure the hello interval
on the interface
Configure the poll interval on
the NBMA interface
Configure the dead time of
the neighboring router on
the interface
Configure the interval for
retransmitting an LSA on an
interface
Use the command...
system-view
interface interface-type
interface-number
ospf timer hello seconds
ospf timer poll seconds
ospf timer dead seconds
ospf timer retransmit interval
4-22
Remarks
—
—
Optional
By default, p2p and broadcast
interfaces send Hello packets
every 10 seconds; while p2mp and
NBMA interfaces send Hello
packets every 30 seconds.
Optional
40 seconds by default
Optional
By default, the dead time for the
OSPF neighboring router on a p2p
or broadcast interface is 40
seconds and that for the OSPF
neighboring router on a p2mp or
NBMA interface is 120 seconds.
Optional
5 seconds by default