3Com 5500 SI - Switch - Stackable, Configuration Manual

Page: 242 / 686

242 C
HAPTER
16: IP R
OUTING
P
ROTOCOL
O
PERATION
Perform the following configuration in Interface View:
By default, the priority of the Interface is 1 in the DR election. The value can be taken
from 0 to 255.
Configuring the Peer
In an NBMA network, some special configurations are required. Since an NBMA
interface on the network cannot discover the adjacent router through broadcasting
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.
By default, the preference for the neighbor of NBMA interface is 1.
Setting the Interval of Hello Packet Transmission
Hello packets are the most frequently sent packets. They are periodically sent to the
adjacent router for discovering and maintaining adjacency, and for electing a 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
By default, P2P and broadcast interfaces send Hello packets every 10 seconds, and
P2MP and NBMA interfaces send Hello packets every 30 seconds.
Table 227 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
Table 228 Configuring the peer
Operation Command
Configure a peer for the NBMA interface
peer ip_address [ dr-priority
dr_priority_number ]
Remove the configured peer for the NBMA
interface
undo peer ip_address
Table 229 Setting Hello Timer and Poll Interval
Operation Command
Set the hello interval of the interface
ospf timer hello seconds
Restore the default hello of the interface
undo ospf timer hello
Set the poll interval on the NBMA interface
ospf timer poll seconds
Restore the default poll interval
undo ospf timer poll