RE: OSPF over Frame Relay

From: Malcolm Price (malcolm@xxxxxxxxxxx)
Date: Sun Aug 04 2002 - 07:14:38 GMT-3

   
I follow what you say, that makes more sense.

I did a debug ip packet and all the ip broadcasts were forwarded using the
frame-relay map....broadcast and that's why I questioned the need for the ip
ospf network command.

Thanks for your input, its appreciated,
Malcolm

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
ccie candidate
Sent: Saturday, August 03, 2002 11:28 PM
To: ccielab@groupstudy.com; Malcolm Price
Subject: Re: OSPF over Frame Relay

that is a good question ..i have been thinking of the same question some
time ago ...here are my conclusions (that is only what i thought )

by definition , frame relay is NBMA network and if you kept it without
change , ospf will not bother to send the broadcast (hellos) !!! simply
because he consider the network as NBMA and there is no place for the hellos
here !:)

that is why you need to use the nieghbor command , this will inform the OSPF
to change the broadcast to unicat traffic directed to the neighbor , well
now he can send the hellos to certain guys on the NBMA network .

or simply change the network type (from OSPF point of view ) to let the
router start send the broadcast /multicast hellos , only at this point he
will start consider the broadcast keyword in your frame map .

i hope this help 

--

On Sat, 3 Aug 2002 20:03:39
 Malcolm Price wrote:
>Hi Group,
>
>This is probably a simple question which really I should know, but I was
>wondering if someone could clarify the need for the following:
>
>When using OSPF over NBMA Frame Relay, given the following 4 router
>multipoint scenario:
>
>interface serial0
>encapsulation frame-relay
>ip address 172.16.2.1 255.255.255.0
>frame-relay map ip 172.16.2.4 200 broadcast
>frame-relay map ip 172.16.2.5 200 broadcast
>frame-relay map ip 172.16.2.6 200 broadcast
>!
>router ospf 100
>network 172.16.0.0 0.0.255.255 area 0
>
>
>As I understand, using the command "frame-relay map ip 172.16.2.4 200
>broadcast" would forward "broadcast" and multicast packets across the NBMA
>network.
>
>Given this useage, why would we need to use the following command to
forward
>ospf multicasts/broadcasts:
>
>ip ospf network broadcast
>
>if the purpose of these commands is to broadcast forward ospf info..?
>
>
>I understand what the ip ospf network commands represent and their
function,
>it's clarification of the broadcast option of the frame-relay map command I
>was looking for?.
>
>Many thanks,
>Malcolm
>
>
>
>Malcolm Price M.Phil. MBCS C.Eng.
>Technical Director
>LanBase Technologies
>www.lanbase.com

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