From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Aug 18 2004 - 21:53:00 GMT-3
John,
No, the "ip igmp join-group" command makes the router a client
of the group. The "feed" is the ping, trace, etc. The actual traffic
flow is the feed. Having the router join the group is just a way to
have an igmp join message sent upstream in order to make the feed flow
the direction you want.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: John Matus [mailto:jmatus@pacbell.net]
> Sent: Wednesday, August 18, 2004 6:01 PM
> To: Brian McGahan; lab
> Subject: Re: multicast basic question
>
> brian,
> so if a task states something to the effect of "generate (150.1.1.1,
> 255.5.5.5) traffic" then just joining it to the multicast group
255.5.5.5
> will do just that via this "feed"?
>
>
>
> John D. Matus
> MCSE, CCNP
> Office: 818-782-2061
> Cell: 818-430-8372
> jmatus@pacbell.net
> ----- Original Message -----
> From: "Brian McGahan" <bmcgahan@internetworkexpert.com>
> To: "John Matus" <jmatus@pacbell.net>; "lab" <ccielab@groupstudy.com>
> Sent: Wednesday, August 18, 2004 3:48 PM
> Subject: RE: multicast basic question
>
>
> > John,
> >
> > Anytime to send traffic with a multicast destination, you are
> > generating a "feed". The router can generate this with features
such as
> > ping, traceroute, or SAA. The reason the S,G entry shows up in R2's
> > routing table is because it received a "feed" from 150.1.1.1 going
to
> > the group 255.5.5.5. If R1 receives an ICMP echo-reply from R2,
then
> > the end to end path is good. If R1 doesn't receive the reply, the
> > majority of the time it is due to RPF failure.
> >
> >
> > HTH,
> >
> > Brian McGahan, CCIE #8593
> > bmcgahan@internetworkexpert.com
> >
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com
> > Toll Free: 877-224-8987 x 705
> > Outside US: 775-826-4344 x 705
> > 24/7 Support: http://forum.internetworkexpert.com
> > Live Chat: http://www.internetworkexpert.com/chat/
> >
> >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf
> > Of
> > > John Matus
> > > Sent: Wednesday, August 18, 2004 3:51 PM
> > > To: lab
> > > Subject: multicast basic question
> > >
> > > ok, here goes...
> > > in a lab scenario, one where there is no real multicast feed to
play
> > > with....
> > > say the lab asks you to configure pim on routers 1, 2 and 3 and
also
> > asks
> > > that
> > > routers 1, 2, and 3 join multicast group 225.5.5.5. and then asks
> > that
> > > router
> > > 1 be able to get ping responses from 2 and 3....
> > >
> > > when you join an interface to a multicast group ( ip igmp
join-group
> > > 225.5.5.5), i've noticed that it will show up in the other
router's
> > mroute
> > > tables as (150.1.1.1, 255.5.5.5) (from r2's perspective). my
> > question
> > > is
> > > does that somehow create a 'source' of multicast traffic since it
> > shows up
> > > in
> > > the mroute table? some of the labs i've seen will ask you to
> > configure
> > > multicast and then tell you that you can use static mroutes, but i
> > don't
> > > see
> > > how it is possible to test for RPF is there is no real multicast
> > source.
> > > so
> > > i'm confused about 1) what a multicast source is in these lab
> > scenarios
> > > and 2)
> > > how do you test for RPF without a 'source'
> > >
> > > also, if i join routers 1, 2, and 3 to multicast group 225.5.5.5,
> > should
> > > they
> > > all respond to pings to that group....and if they don't, am i
supposed
> > to
> > > use
> > > static mroutes to get to each other? (this is all just
hypothetical of
> > > course)
> > >
> > > thanks in advance!
> > >
> > >
> > >
> > > John D. Matus
> > > MCSE, CCNP
> > > Office: 818-782-2061
> > > Cell: 818-430-8372
> > > jmatus@pacbell.net
> > >
> > >
> >
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