Asante Technologies 35516 Configure Ospf for Non-broadcast Networks, Configure Area Parameters

To configure the OSPF network type, use the following command in interface configuration mode.

Command	Purpose
ip ospf network {broadcast	Configure the OSPF network type for a
non-broadcast	specified interface.
point-to-multipoint point-to-point}

5.7.6 Configure OSPF for Non-broadcast Networks

To configure routers that interconnect to non-broadcast networks, perform the following task in router configuration mode.

Command	Purpose
neighbor ip-address[priority number]	Configure routers interconnecting to
[poll-interval seconds]	non-broadcast networks.

As there might be many routers attached to an OSPF network, a designated router is selected for the network. It is necessary to use priority and poll-interval parameters in the designated router selection if broadcast capability is not configured. These parameters need only be configured in those devices that are eligible to become the designated router or backup designated router.

5.7.7 Configure Area Parameters

The user can configure several area parameters including authentication, defining stub areas, and assigning specific costs to the default route.

Authentication allows password-based protection against unauthorized access to an area. Stub areas are areas into which information on external routes is not sent. Instead, there is a default external route (generated by the area border router) into the stub area for destinations outside the autonomous system. To further reduce the number of link state advertisements sent into a stub area, no-summaryconfiguration on the ABR is allowed to prevent it from sending summary link advertisement into the stub area.

In router configuration mode, specify any of the following area parameters as needed for the network.

Command	Purpose
area {area-id area-address}	Enable authentication for an OSPF area.
authentication
area {area-id area-address}	Enable MD5 authentication for an OSPF
authentication message-digest	area.
area {area-id area-address}	Define an area as a stub area.
stub [no-summary]
area {area-id area-address}	Assign a specific cost to the default
default-cost cost	summary route used for the stub area.
area {area-id area-address}	Define an area to be advertised into the
export-list access-list	other areas.
area {area-id area-address}	Define an area to be allowed in the specified
import-list access-list	area.
area {area-id area-address}	Set shortcutting behavior through an area.
shortcut {default disable enable}

5.7.8 Configure OSPF Not So Stubby Area (NSSA)

The NSSA is similar to OSPF stub area. NSSA does not flood Type 5 external link state advertisements (LSAs) from the core into the area, but it has the ability of importing AS external routes in a limited fashion within the area.

The OSPF Specification (RFC 1583) prohibits the summarizing or filtering of Type 5 LSAs. It is an OSPF requirement that Type 5 LSAs always be flooding throughout a routing domain. NSSA allows importing

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