3Com Router 3031, Command Reference Manual

Page: 589 / 838

OSPF Configuration Commands 589
ospf network-type Syntax
ospf network-type { broadcast | nbma | p2mp | p2p }
undo ospf network-type
View
Interface view
Parameter
■
broadcast: Changes the interface network type to broadcast.
■
nbma: Changes the interface network type to Non-Broadcast Multicast Access.
■
p2mp: Changes the interface network type to point-to-multipoint.
■
p2p: Changes the interface network type to point-to-point.
Description
Using the ospf network-type command, you can configure the network type of
OSPF interface. Using the undo ospf network-type command, you can restore the
default network type of the OSPF interface.
OSPF divides networks into four types by link layer protocol:
■
Broadcast: If Ethernet is adopted, OSFP defaults the network type to broadcast.
■
Non-Broadcast Multi-access (nbma): If Frame Relay, ATM, HDLC or X.25 is
adopted, OSPF defaults the network type to NBMA.
■
Point-to-Multipoint (p2mp): OSPF will not default the network type of any link
layer protocol to p2mp. The general undertaking is to change a partially
connected NBMA network to p2mp network if the NBMA network is not
fully-meshed.
■
Point-to-point (p2p): If PPP or LAPB is adopted, OSPF defaults the network type
to p2p.
If there is a router not supporting multicast address on the broadcast network, the
interface network type can be changed to NBMA. The interface network type can
also be changed from NBMA to broadcast.
A network that can be called an NBMA network or can be changed to a broadcast
network should satisfy the following condition: there is a virtual circuit directly
connects any two routers on the network. In other words, the network is
full-meshed. If the network cannot satisfy this condition, the interface network
type must be changed to point-to-multipoint. In this way, these two routers can
exchange routing information via a router directly connected with the two routers.
If there are only two routers running OSPF protocol on the same network
segment, the interface network type can be changed to point-to-point.
Note: When the network type of an interface is NBMA or it is changed to NBMA
manually, the
peer command must be used to configure the neighboring point.
For the related command, see ospf dr-priority .
Example
Set the interface serial1/0/0 to NBMA type.