3Com 10014299 Configure the Network Type of the Ospf Interface, Configure Sending Packet Cost

Configuring OSPF 427

hello packet before this interface sets up neighboring relations with the adjacent routers.

The interface can be configured into nbma mode on the broadcast network without multi-access capability.

If not all routers are inter-reachable on NBMA network, the interface can be configured into p2mp mode.

If the router has only one opposite terminal in NBMA network, the interface can also be changed to p2p mode.

The difference between an NBMA network and a point-to-multipoint network includes the following distinctions:

■In the OSPF protocol, NBMA refers to those as fully connected, nonbroadcast and multi-access networks. But point-to-multipoint network does not necessarily require full connection.

■DR and BDR should be elected on NBMA while there is no DR or BDR on point-to-point network.

■NBMA is a default network type. For example, if the link layer protocol is X.25 or frame relay, OSPF regards the network type of this interface as NBMA (whether the network is wholly connected). Point-to-multipoint is not a default network type. No link layer protocol can be considered as a point-to-multipoint protocol because it must be a modification from other network types. The most common practice is to change the not fully connected NBMA to a point-to-multipoint network.

■An NBMA network sends messages in unicast mode and the peer must be configured manually. In point-to-multipoint network, messages are sent either in unicast mode or in multicast mode.

Perform the following configurations in interface view.

Table 490 Configure the Network Type of the OSPF Interface

Operation	Command
Configure the network type of the OSPF	ospf network-type { broadcast nbma
interface	p2mp		p2p }
Delete the specified OSPF network type	undo	ospf network-type { broadcast
	nbma		p2mp p2p }

After a new OSPF network type is configured, the old network type on the interface will be replaced automatically.

Configuring Sending You can configure the cost of sending a packet on the interface, otherwise OSPF Packet Cost automatically calculates the cost value according to the baud rate of the current

interface.

Perform the following configurations in interface view.

Table 491 Configure Sending Packet Cost

Operation

Command