From: SHARMA,MOHIT (HP-Germany,ex1) (mohit.sharma@hp.com)
Date: Fri Jul 04 2003 - 09:39:10 GMT-3
I think if you do not specify the broadcast keyword, the demand circuit
would not be able to form any ospf adjacencies anyway.
In this specific example, Cisco is denying ospf traffic as they dont want
ospf hellos to bring up the link. This is a special case in which the two
sites are only connected with the ISDN. Also they have a static route, on
the remote site, so that the intersting traffic "only" will be able to bring
up the link.
Normally if you are using ospf demand circuit and you deny ospf in the
intersting traffic, and there is a change in the ospf topolgy, ospf will try
to bring up the link, would fail and would bring down the neighborship on
the ISDN, even with the demand circuit configured.
Please correct me if I m wrong.
Hope it helps.
-----Original Message-----
From: Georg Pauwen [mailto:pauwen@hotmail.com]
Sent: Friday, July 04, 2003 1:09 PM
To: ccie2be@nyc.rr.com; ccielab@groupstudy.com
Subject: Re: OSPF Demand Circuit
Hello,
AFAIK, the broadcast statement in the dialer map causes broadcasts to bring
up the link, hence you need an access list denying OSPF packets in the
dialer-list. Without the broadcast statement in the dialer map, you don4t
need the access list.
Regards,
Georg
>From: "ccie2be" <ccie2be@nyc.rr.com>
>Reply-To: "ccie2be" <ccie2be@nyc.rr.com>
>To: "Group Study" <ccielab@groupstudy.com>
>Subject: OSPF Demand Circuit
>Date: Fri, 4 Jul 2003 06:22:15 -0400
>
>Hi,
>
>After checking the archieves, I didn't find anything that specifically
>addressed this question, so here goes.
>
>I thought that when a BRI interface is configured as an ip ospf
>demand-circuit, it will automatically suppress ospf hello's as long as the
>interface is configured as a p2p or p2m ospf network type.
>
>However, in the example at
>http://www.cisco.com/warp/public/129/config-bri-map.html , it shows an
>access
>list being used to prevent ospf hello's in addition to the ip ospf
>demand-circuit command being configured.
>
>Is it really necessary (or just sometimes necessary) to use an access list
>to
>deny ospf hello's (packets addressed to 224.0.0.5) when one side of the
>isdn
>circuit is configured as an ip ospf demand circuit? If so, why is that?
>Also, if the access-list in addtion to the ip ospf demand circuit is only
>needed in certain situations, what are those situations?
>
>Thanks, Jim
>
>
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