Syntax Description broadcast

non-broadcast point-to-multipoint [non-broadcast]

Sets the network type to broadcast.

Sets the network type to NBMA.

Sets the network type to point-to-multipoint.

The optional non-broadcast keyword sets the point-to-multipoint network to be nonbroadcast. If you use the non-broadcast keyword, the neighbor command is required.

Defaults

Depends on the network type.

Command Modes

Interface configuration

Command History Release Modification

10.0

This command was introduced.

10.3

The point-to-multipoint keyword was added.

11.3 AA The non-broadcast keyword used with the point-to-multipoint keyword was added.

11.3 AA The non-broadcast keyword used with the point-to-multipoint keyword was added.

Usage Guidelines Using this feature, you can configure broadcast networks as nonbroadcast multiaccess (NBMA)

networks when, for example, you have routers in your network that do not support multicast addressing. You can also configure nonbroadcast multiaccess networks (such as X.25, Frame Relay, and SMDS) as broadcast networks. This feature saves you from having to configure neighbors.

Configuring NBMA networks as either broadcast or nonbroadcast assumes that there are virtual circuits from every router to every router or fully meshed network. This is not true for some cases, for example, because of cost constraints or when you have only a partially meshed network. In these cases, you can configure the OSPF network type as a point-to-multipoint network. Routing between two routers that are not directly connected will go through the router that has virtual circuits to both routers. You do not need to configure neighbors when using this feature.

If this command is issued on an interface that does not allow it, it will be ignored.

OSPF has two features related to point-to-multipoint networks. One feature applies to broadcast networks; the other feature applies to nonbroadcast networks.

• On point-to-multipoint, broadcast networks, you can use the neighbor command and you must specify a cost to that neighbor.

• On point to multipoint, nonbroadcast networks, you must use the neighbor command to identify neighbors. Assigning a cost to a neighbor is optional.

Examples The following example sets your OSPF network as a broadcast network:

interface serial 0 ip address 192.168.77.17 255.255.255.0 ip ospf network broadcast encapsulation frame-relay

The following example illustrates a point-to-multipoint network with broadcast.

interface SerialO ip address 10.0.1.1 255.255.255.0 encapsulation frame-relay ip ospf cost 100

ip ospf network point-to-multipoint frame-relay map ip 10.0.1.3 202 broadcast frame-relay map ip 10.0.1.4 203 broadcast frame-relay map ip 10.0.1.5 204 broadcast frame-relay local-dlci 200

router ospf 1 network 10.0.1.0 0.0.0.255 area 0 neighbor 10.0.1.5 cost 5 neighbor 10.0.1.4 cost 10

Related Commands Command Description

frame-relay map

Defines mapping between a destination protocol address and the DLCI used

to connect to the destination address.

neighbor (OSPF)

Configures OSPF routers interconnecting to nonbroadcast networks.

x25 map

Sets up the LAN protocols-to-remote host mapping.

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