OSPF not connect

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Jan 12th, 2009
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We have a frame-relay network and 2 sites have layer 2 connectivity. On each interface we have "frame-relay map ip x.y.x 201 broadcast" Why do we have to define neighbor inorder for the ospf to connect?

our interface is setting at:


Serial1/0 is up, line protocol is up

Internet Address 192.168.1.1/24, Area 0

Process ID 1, Router ID 1.1.1.1, Network Type NON_BROADCAST, Cost: 64


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Giuseppe Larosa Mon, 01/12/2009 - 06:36
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Hello Stanley,

the OSPF network is NBMA

Process ID 1, Router ID 1.1.1.1, Network Type NON_BROADCAST


that is the default for OSPF on a main interface with FR encapsulation.

In this case OSPF assumes it cannot use multicast packets and expects you to configure neighbor commands.


If you configure a point-to-point subinterface on each router and you move ip addressing to it and you use

frame-rel interface-dlci 201


you will see the network type will be point-to-point and the neighbor command is not needed anymore


you could even use

ip ospf network broadcast in your current config and you can remove the neighbor statements


Hope to help

Giuseppe



stanleyworks Mon, 01/12/2009 - 06:46
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Qiuslar,


Thank you for reply to my message.

so what is the pseudo-broadcast good for? I thought that support broadcast and multicast? maybe this support for rip and eigrp?


Thanks,


Giuseppe Larosa Mon, 01/12/2009 - 12:55
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Hello Stanley,

OSPF is link state so it classifies links using the concept of OSPF network type.

With RIP and EIGRP you can face problems in hub and spoke topologies for the split horizon concept but the broadcast option in frame-relay map command works well with them


Hope to help

Giuseppe

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