From: Jonathan V Hays (jhays@jtan.com)
Date: Wed Apr 02 2003 - 00:11:31 GMT-3
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf Of Jason Cash
> Sent: Tuesday, April 01, 2003 6:51 PM
> To: ccielab@groupstudy.com
> Subject: OSPF NBMA -without neighbors-
>
> There are no neighbor statements. Does the 'broadcast'
> statement at the end of the 'fr map' make the medium a
> broadcast and thus change the network type? Does this negate
> the need for static neighbors?
>
>
No. The "frame map" broadcast keyword does not change the network type.
It allows the IOS to simulate a broadcast physical type on an NBMA
network by using unicasts. See:
--- http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/ wan_r/wrdfrely.htm#1020191"The broadcast keyword provides two functions: it forwards broadcasts when multicasting is not enabled, and it simplifies the configuration of OSPF for nonbroadcast networks that will use Frame Relay.
The broadcast keyword might also be required for some routing protocols-for example, AppleTalk-that depend on regular routing table updates, especially when the router at the remote end is waiting for a routing update packet to arrive before adding the route.
By requiring selection of a designated router, OSPF treats a nonbroadcast, multiaccess network such as Frame Relay in much the same way as it treats a broadcast network. In previous releases, this required manual assignment in the OSPF configuration using the neighbor interface router command. When the frame-relay map command is included in the configuration with the broadcast keyword, and the ip ospf network command (with the broadcast keyword) is configured, there is no need to configure any neighbors manually. OSPF will now automatically run over the Frame Relay network as a broadcast network. (See the ip ospf network interface command for more detail.) " --- Are your routing tables complete? I've had OSPF adjacency without routes on NBMA networks and seen the routes pop into the routing table after adding the "neighbor" command.
BTW, unless the instructions prohibit it, using "ip ospf network point-to-multipoint" is preferred over "neighbor" commands to fix this situation.
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