From: Carlos Trujillo Jimenez (nergal888@hotmail.com)
Date: Wed Dec 05 2007 - 00:18:08 ART
Not trying to enter into discussion but I Agree with yemi Salaus answer, is
the most complete answer about IP PIm autorp listener feature and sparse
dense feature also.
I have also proven those commands and what Yemi Salau Says is completelly
true I have labbed it.
>From: nhatphuc <nhatphuc@gmail.com>
>X-OriginalArrivalTime: 04 Dec 2007 12:57:23.0146 (UTC)
>FILETIME=[366102A0:01C83675]
>
>Hi all,
>
>I've received 3 answers, two of which agree with me, the other doesn't.
>
>Per my testing, R3 and R5 can still receive RP mapping info without autorp
>listener command. But in the IEWB 4 lab4, there is a scenario in which they
>configure listener command on R3 and R5.
>
>I don't know if it is a must or they just add the command for sure as
>Shiran
>Quez said.
>
>To Salau Yemi: Have you done lab 4 IEWB4 or tested this command on devices?
>
>To Shiran Quez, Gupta Gopal: What do you think about Salau Yemi's answer?
>
>Thank you for your replies
>
>Phuc
>
>
>On Dec 4, 2007 5:05 PM, Salau, Yemi <yemi.salau@siemens.com> wrote:
>
> > Basically, ip pim autorp listener is basically telling the router to
> > flood multicast traffic for 2 auto-rp groups 224.0.1.39 and 224.0.1.40
> > across interfaces operating in PIM sparse mode. I believe you know cRPs
> > uses 224.0.1.39 to announce/advertise themselves to the MA, and in turn
> > the MA routers receive these multicasts, and periodically advertises
> > this information to multicast group 224.0.1.40
> >
> > The thing is, before MA routers can join 224.0.1.39, then need to know
> > who the RP for that group is, also, before multicast routers can join
> > 224.0.1.40 to receive the RP information from MAs, they need to know who
> > the RP for 224.0.1.40 is. Hence the old recursive design flaw within
> > multicast technology. Before users join a group, they need who the RP
> > is, and before they know who the RP is they need to joing the group.
> >
> > Hence, why some techies use sparse-dense-mode, so that for those groups
> > which you don't know who the RP is, you just switch to dense mode to
> > flood the traffic, (eg. cRPs using flooding of traffic to group
> > 224.0.1.39, and MAs using flooding of traffic to group 224.0.1.40)
> >
> > Another way to do this is to use sparse-mode (which you did), but ip
> > auto-rp listener is disabled by default now, so you have to enable it to
> > tell routers to turn on "DENSE" mode operation for only the 2 AUTO-RP
> > groups ... 224.0.1.39 and 224.0.1.40.
> >
> > Your RPs need to flood 224.0.1.39 traffic to MAs, so MAs have to join
> > that group, since they don't know who the RP is for 224.0.1.39, they
> > then operate the group in dense mode. Similarly, your other multicast
> > routers should join the 224.0.1.40, and understand how to flood the
> > 224.0.1.40 traffic as well in case there are downstream routers who need
> > the information. Since they don't know who the RP for 224.0.1.40 is,
> > they then operate the group in dense mode.
> >
> > NOTE: ip auto-rp listener doesn't flood traffic for all multicast groups
> > there is, only for the auro-rp groups.
> >
> > So to answer your question in a single statement:- YES, you need to do
> > ip auto-rp listener for R3 and R5, if you're using sparse-mode and
> > auto-rp for them. If you don't want to use auto-rp, then just use
> > static-rp then (hardcoding who the RP is to them)
> >
> > Many Thanks
> >
> > Yemi Salau
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Gupta, Gopal (NWCC)
> > Sent: Tuesday, December 04, 2007 9:25 AM
> > To: nhatphuc; Cisco certification
> > Subject: RE: IP PIM AutoRP Listener placement?
> >
> > In my opinion you don't need coz, R1 will flood through dense mode abt
> > RP and further R4 will do the same; provided that IP pim auto RP is
> > configured on R1,R4 and R2 so, There should be no problem for R5 to
> > accept that info about the RP.
> >
> > HTH
> > Gops
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > nhatphuc
> > Sent: Tuesday, December 04, 2007 14:44
> > To: Cisco certification
> > Subject: IP PIM AutoRP Listener placement?
> > Importance: Low
> >
> > Hi Group,
> >
> > My topology is like this:
> >
> > R1------R2-----R3
> > |
> > |
> > R4
> > |
> > |
> > R5
> >
> > PIM Sparse Mode is configured. R1 is Mapping Agent, R2 and R4 are cRP. I
> > choose to use ip pim autorp listener.
> >
> > My opinion is: No need to configure ip pim autorp listener on R3 and R5.
> >
> > My question: Do you have the same idea as me? Why/Why not?
> >
> > Thank you
> >
> > Phuc
> >
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