Cisco Systems 78-11741-02 Wireless Office Headset User Manual


 
Configuring OSPF
Configuring OSPF over Different Physical Networks
IPC-226
Cisco IOS IP Configuration Guide
Configuring OSPF over Different Physical Networks
OSPF classifies different media into the following three types of networks by default:
Broadcast networks (Ethernet, Token Ring, and FDDI)
Nonbroadcast multiaccess (NBMA) networks (Switched Multimegabit Data Service (SMDS),
Frame Relay, and X.25)
Point-to-point networks (High-Level Data Link Control [HDLC], PPP)
You can configure your network as either a broadcast or an NBMA network.
X.25 and Frame Relay provide an optional broadcast capability that can be configured in the map to
allow OSPF to run as a broadcast network. Refer to the x25 map and frame-relay map command
descriptions in the Cisco IOS Wide-Area Networking Command Reference publication for more detail.
Configuring Your OSPF Network Type
You have the choice of configuring your OSPF network type as either broadcast or NBMA, regardless
of the default media type. Using this feature, you can configure broadcast networks as NBMA networks
when, for example, you have routers in your network that do not support multicast addressing. You also
can configure NBMA networks (such as X.25, Frame Relay, and SMDS) as broadcast networks. This
feature saves you from needing to configure neighbors, as described in the section “Configuring OSPF
for Nonbroadcast Networks” later in this chapter.
Configuring NBMA, multiaccess networks as either broadcast or nonbroadcast assumes that there are
virtual circuits (VCs) 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 not directly connected will go through the router that has VCs to both routers. Note
that you need not configure neighbors when using this feature.
An OSPF point-to-multipoint interface is defined as a numbered point-to-point interface having one or
more neighbors. It creates multiple host routes. An OSPF point-to-multipoint network has the following
benefits compared to NBMA and point-to-point networks:
Point-to-multipoint is easier to configure because it requires no configuration of neighbor
commands, it consumes only one IP subnet, and it requires no designated router election.
It costs less because it does not require a fully meshed topology.
It is more reliable because it maintains connectivity in the event of VC failure.
Router(config-if)# ip ospf message-digest-key
key-id md5 key
Enables OSPF MD5 authentication. The values for the key-id and
key arguments must match values specified for other neighbors on a
network segment.
Router(config-if)# ip ospf authentication
[message-digest | null]
Specifies the authentication type for an interface.
Command Purpose