RE: OSPF NBMA

From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Sun Oct 05 2003 - 22:40:40 GMT-3


OSPF does not check to see if 'broadcast' is supported on the interface to
determine the OSPF network type. A Frame-relay physical interface and
multipoint subinterface are non-broadcast as far as OSPF is concerned
regardless if 'broadcast' is mapped to the DLCI. You would need to manually
inform OSPF that the network supports 'broadcast' by changing the OSPF
network type to broadcast.

Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Toll Free: 877-224-8987
Direct: 775-745-6404 (Outside the US and Canada)
Internetwork Expert, Inc.
http://www.InternetworkExpert.com

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Mac
Sent: Sunday, October 05, 2003 6:11 PM
To: ccielab@groupstudy.com
Subject: OSPF NBMA

Hi, Group,

I just grabed some configuration from cisco website as below, but just don't
know why broadcast key-word is issued because that would make it work as a
broadcast network. Even if there is no neighbor command, the network should
work. Your clarification is greatly appreciated.

Thanks,

Mac

Configurations for NBMA (Using Neighbor Statements)
http://www.cisco.com/warp/public/104/18.html
      R4-4K

interface Loopback0
      ip address 3.3.3.3 255.255.255.255
     !
     interface Serial2
      ip address 1.1.1.2 255.255.255.0
      encapsulation frame-relay
      no keepalive
      frame-relay map ip 1.1.1.1 16 broadcast
     !
     router ospf 1
      network 1.1.1.0 0.0.0.255 area 0
     !

      R1-7010

interface Loopback0
      ip address 2.2.2.2 255.255.255.255
     !
     interface Serial1/0
      ip address 1.1.1.1 255.255.255.0
      encapsulation frame-relay
      no keepalive
      clockrate 2000000
      frame-relay map ip 1.1.1.2 16 broadcast
     !
     router ospf 1
      network 1.1.1.0 0.0.0.255 area 0
      neighbor 1.1.1.2 priority 2
     !

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