From: Salau, Yemi (yemi.salau@siemens.com)
Date: Tue Dec 04 2007 - 10:23:34 ART
Hang on a sec Guys, I was only trying to explain the principle of
operations and what we would do from best practises.
Ok, there is no RP for 224.0.1.40 so R1 will just flood the necessary
RPInfo, so R2/R4 will pick it and forward it to R3/R5 respectively.
The receivers of the information wouldn't need to joing 224.0.1.40, they
can't because no RP, so they just forward it on if necessary. And Yes,
R3/R5 wouldn't need to forward these information to anyone behind them,
so they don't need to join 224.0.1.40, and don't need to flood them out.
But what of scalability, say in the future your customer want to expand
their network, or extend the multicast domain to their regional sites?
When I think of Tech Solutions, I always have and bear in mind that
scalability factor and ofcourse resilience as well. Sorry for any
confusion caused.
Many Thanks
Yemi Salau
________________________________
From: Joseph Saad [mailto:joseph.samir.saad@gmail.com]
Sent: Tuesday, December 04, 2007 1:04 PM
To: nhatphuc
Cc: Salau, Yemi; Gupta, Gopal (NWCC); Cisco certification
Subject: Re: IP PIM AutoRP Listener placement?
Make this 3:1. autorp listener is not required on the stub routers (R3
and R5)
On Dec 4, 2007 4:48 PM, nhatphuc <nhatphuc@gmail.com> wrote:
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
<mailto: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
<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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