From: Chee Chew Leong (cleong3@csc.com)
Date: Tue Dec 26 2006 - 01:51:57 ART
Dear Brian,
I can't understand your statement why we can't get the router to manually
inititiate the (S,G) join.
We always can use ip igmp join-group x.x.x.x source y.y.y.y to select the
source, and hence we join (S,G).
I am really not familiar with SSM, perhaps I am missing something here.
Can help to explain more?
Regards
"Brian McGahan" <bmcgahan@internetworkexpert.com>
Sent by: nobody@groupstudy.com
12/20/2006 08:00 AM
Please respond to
"Brian McGahan" <bmcgahan@internetworkexpert.com>
To
"Andre Serrao" <andreserrao@gmail.com>, "Cisco certification"
<ccielab@groupstudy.com>
cc
Subject
RE: Multicast Question: SSM vs Dense Mode?
Per the RFC only the 232.0.0.0/8 range is valid for
source
specific multicast. SSM is mainly used to support IGMPv3 aware hosts
than can send (S,G) joins instead of traditional (*,G) joins, but has
other applications such as MDT for Multicast MPLS VPN support.
The key here is the question says that the router should
join
the group 227.x.x.x. As this is outside of the SSM range, and secondly
since the router cannot product a (S,G) join with the "ip igmp
join-group" command, SSM is not valid. Technically you can configure
the Cisco routers in the transit path to forward (S,G) joins outside of
the 232.0.0.0/8 range with the "ip ssm" command, but you still can't get
the router to manually initiate the (S,G) join.
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Andre Serrao
> Sent: Tuesday, December 19, 2006 5:18 PM
> To: Cisco certification
> Subject: Re: Multicast Question: SSM vs Dense Mode?
>
> Scott and GS,
>
> This scenario has two routers (R1,R4), interconnected via GRE tunnel
> (since
> there are 2-3 other routers in between them). Only these two routers
have
> multicast enabled. We want a server in the same vlan as Router 1's
fa0/0
> to
> ping group 227.69.53.7 (R4's fa0/0 has ip igmp join-group
227.69.53.7).
>
> So, it's a pretty simple scenario (pt-to-pt) link between 2 multicast
> routers. Like I mentioned in the previous message, it states "do not
use
> any
> RP assignments". There is no explicit indication about the pim mode.
So,
> is
> this a situation that could be solved by using SSM?
>
> I wasn't so much concerned with this scenario in particular, but
mostly
> with
> the application of SSM in general.
>
> Thanks in advance for your help,
> Andre
>
>
> On 12/19/06, Andre Serrao <andreserrao@gmail.com> wrote:
> >
> > If a question states "do not use any RP assignments" (IEWB Lab17),
is it
> > OK to use SSM or we need to use dense mode?
> >
> > I made it work with SSM and have not used Auto-RP, BSR, and static
> > routing, yet the answer says it should be dense mode.
> >
> > If I can't use SSM here, could you please tell a situation in which
SSM
> is
> > the applicable solution? I haven't done any lab yet that uses it.
> >
> > Thanks,
> > Andre
>
>
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