Re: Multicast Understanding

Karim

How do you know both routers are forwarding? What show commands are you
running that show this?

On Sun, Oct 11, 2009 at 6:40 AM, karim jamali <karim.jamali_at_gmail.com>wrote:

> Dear Divin,
>
> I didn't get you clearly. Are you saying that both routers can forward @
> the
> same time as this is what is happening with me?
> Please explain more. The thing that is happening with me is that both
> routers (R2,R3) are forwarding multicast traffic to the presumed client
> (R4). However the thing is that I thought that only one forwarder will be
> elected on a common subnet and this router will forward multicast traffic
> to
> the subnet.
>
> Can you please explain in more detail?
>
> Thank You
>
> Best Regards,
> On Sun, Oct 11, 2009 at 3:08 PM, Divin Mathew John <divinjohn_at_gmail.com
> >wrote:
>
> > yep.
> >
> > highest is the DR. but lowest ip address needn't necessarily forward
> > multicast traffic onto the broadcast domain.1
> >
> > The assert election criteria are as follow in decreasing order of
> priority:
> >
> > 1- administrative distance to the source S (10.10.10.1)
> >
> > 2- Cost of the route to S (10.10.10.1)
> >
> > 3- Highest multicast interface IP address.
> >
> > refer
> http://cciethebeginning.wordpress.com/2008/07/16/pim-assert-message/
> >
> > On Sun, Oct 11, 2009 at 3:59 PM, karim jamali <karim.jamali_at_gmail.com
> >wrote:
> >
> >> Dear Gents,
> >>
> >> I have a confusion regarding multicast. I am running a sparse-mode
> >> scenario
> >> which is shown in the attached visio file.
> >> R1 s1/0 -->R2 s1/0 (12.0.0.0/24)
> >> R1 s1/1 -->R3 s1/0 (13.0.0.0/24)
> >>
> >> R2 fa0/0-->R3 fa0/0(23.0.0.0/24)
> >> R2 fa0/1 -->R3 fa0/1 -->R4 fa0/1 all on the same subnet (123.0.0.0/24)
> >>
> >> Pim Sparse mode is running on all the common interfaces & neighbor
> >> relationship is formed. On R2, I have a loopback (2.2.2.2) which is the
> RP
> >> of the my network.
> >>
> >> Note that I am running OSPF everywhere.
> >>
> >> The confusion is related to the common subnet of R2,R3,R4. From what I
> >> understood, on every common subnet one Querier,and one Forwarder is
> >> elected,
> >> and one Designated Forwarder is Elected.As far as I understand, the
> >> Querier
> >> is the one sending queries asking if anyone wants to join a certain
> >> group.A
> >> forwarder is the one forwarding the stream to the subnet. The designated
> >> router as far as I understand is the the first layer 3 device which
> knows
> >> about the stream from the streamer,and sends a register message to the
> RP
> >> notifying it that a source exists. Please correct me if any of my
> concepts
> >> is wrong.
> >>
> >> The router with the lowest IP address is the querier and the one with
> the
> >> highest IP address is the forwarder. In the scenario I have shown, R1 is
> >> the
> >> source, R2's loopback is the RP and R4 ethernet interface has joined a
> >> group
> >> (239.1.1.1). When I ping from R1, I notice that the stream on R4 is
> being
> >> received from both R2,and R3?Does this break the concept of forwarder?
> >>
> >> I would be grateful for any help.
> >>
> >> Best Regards,
> >>
> >> KJ
> >>
> >>
> >> Blogs and organic groups at http://www.ccie.net
> >>
> >> _______________________________________________________________________
> >> Subscription information may be found at:
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> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >
> >
> > --
> >
> >
> > Umberto Eco <http://www.quotationspage.com/quote/320.html> - "I felt
> like
> > poisoning a monk."
> >
>
>
>
> --
> KJ
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
>
>
>
>
>
>
>
>

-- 
Bryan Bartik
CCIE #23707 (R&S), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com
Blogs and organic groups at http://www.ccie.net