From: Brian McGahan (brian@cyscoexpert.com)
Date: Fri Jul 04 2003 - 14:41:10 GMT-3
Jim,
This TAC document is wrong. The purpose of running OSPF demand
circuit is to maintain an accurate view of the routing topology, while
minimizing the amount of time that your DDR link is up solely due to
routing protocol traffic.
By denying OSPF as interesting traffic, adjacency cannot be
maintained over the DDR link unless it is up for some other reason.
When the link goes down due to no interesting traffic passing over the
link within the idle timeout, OSPF adjacency will be lost as soon as the
dead interval expires.
When running OSPF demand circuit, OSPF *should* be specified as
interesting traffic.
HTH,
Brian McGahan, CCIE #8593
Director of Design and Implementation
brian@cyscoexpert.com
CyscoExpert Corporation
Internetwork Consulting & Training
Toll Free: 866.CyscoXP
Fax: 847.674.2625
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> ccie2be
> Sent: Friday, July 04, 2003 5:22 AM
> To: Group Study
> Subject: OSPF Demand Circuit
>
> 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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