Re: Auto-RP sparse mode

Hello Experts,

The whole story put short is that Auto-RP depends on two basic functions:
1.Candidate-RP which sends its information to the mapping agent using
224.0.1.39
2.Mapping agent which distributes the results to the other router using
224.0.1.40
3. Most important fact is that 224.0.1.39/224.0.1.40 are dense mode groups.
4. A sparse mode interface can't forward a dense mode group out the
interface, thus the Auto-RP groups will be blocked, and we will not be able
to have a converged domain, i.e. all the routers agreeing on who the RP for
a particular group is.
5. Cisco came up with the 1st solution which was using sparse-dense-mode,
this allows the two Auto-RP groups to be passed, and to reach a converged
domain. A group which has an RP is treated as sparse/a group with no RP is
treated as dense. The ip pim dm-fallback allows a group which lost its RP to
still continue to function/run as a dense mode group.
6. The last solution/permanent one is using sparse-mode and auto-rp
listener. Well eventhough the syntax "ip pim auto-rp listener" has nothing
to do with what the command does, it is saying eventhough these 2 groups
224.0.1.39/224.0.1.40 and although I am only running a sparse mode
interface, I will allow these advertisements ONLY to go through.

HTH,

Best Regards,

On Tue, Aug 10, 2010 at 10:52 PM, Rohit Ghodke <rohit.nw_at_gmail.com> wrote:

> Hello,
>
> Correct me if Im wrong about any of this
>
> The ip pim dm fallback feature is for sparse-dense mode and allows dense
> mode flooding for groups without an RP.
>
> On Tue, Aug 10, 2010 at 9:24 AM, GAURAV MADAN <gauravmadan1177_at_gmail.com
> >wrote:
>
> > For the groups that RP is found : Sparse mode .
> > For the groups where RP is not found : Flooded like dense mode .
> >
> > On Tue, Aug 10, 2010 at 6:51 PM, masroor ali <masror.ali_at_gmail.com>
> wrote:
> > > Hi,
> > >
> > > In auto-RP sparse-dense mode, why the traffic is sent through Dense??
> > > unable to understand the auto-RP listener and ip-dm fallback feature,
> > >
> > >
> > > --
> > > Regards,
> > > Masroor Ali
> > >
> > >
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-- 
KJ
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