From: Petr Lapukhov (petrsoft@gmail.com)
Date: Mon Apr 10 2006 - 14:39:51 ART
Hello,
First, note:
"When an OSPF demand circuit is configured on a link, the periodic OSPF
hellos are suppressed. Periodic hellos are suppressed only on a
point-to-point and point-to-multipoint network type. *On any other
network
type, OSPF hellos are still sent over the interface."
*Next, you don't need to enable "demand-circuit" on every router in
domain
:)
Actually, all routers just need to support that option, i.e.
advertise DC
bit set
in options inside LSA packets. This is default for all moders cisco
routers,
anyway :)
There is a special method (idication LSA) for ABR to signal into
backbone,
if
is has a Non-DC capable ospf router in attached area. This is
mentioned in
document,
too.
HTH
Petr
2006/4/10, san <san.study@gmail.com>:
>
> Petr,
>
>
> I would like to verify my understanding....To enable ip ospf
> flood-reduction, I need to enable "ip ospf demanc-circuit" in all
> routers
> of the area ?
>
> Copy from the URL you sent :
>
>
> The main difference between flooding reduction and demand circuits is
> that former suppresses only periodic LSA refreshes; it does not
> suppress
> periodic hello packets. Thus, the flooding reduction feature does not
impair
> the detection of a neighbor router going down.
>
> Flooding reduction links have the same constraints as demand
> circuits. In
> particular, all routers in the area must support the demand circuit
> feature
> in order for flooding reduction to work. Troubleshooting techniques
> for
both
> demand circuits and flooding reduction links are also common.
>
> This example shows an OSPF flooding reduction feature configuration:
>
> interface POS 0/0
> ip address 192.168.122.1 255.255.255.0
> *ip ospf flood-reduction*
>
>
>
> On 4/10/06, Petr Lapukhov <petrsoft@gmail.com> wrote:
>>
>> Hello, Pandi
>>
>> Check this out:
>>
>> http://www.cisco.com/warp/public/104/dc.html#floodreduc
>>
>> HTH
>> Petr
>>
>> 2006/4/10, PANDI MOORTHY < moorthypandi@gmail.com>:
>>>
>>> Hi Group,
>>>
>>> These two ospf commands always confuse me. Could any one explain
>>> to me
>> the
>>> difference?
>>>
>>>
>>>
>>> "ip ospf flood-reduction"
>>>
>>>
>>> "ip ospf demand-circuit"
>>>
>>> Regards.
>>> Pandi
>>
>>
>
>
> --
> Thanks & Rgds
> SAN
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