From: keith tokash (ktokash@hotmail.com)
Date: Tue Feb 19 2008 - 00:27:51 ARST
The only other Cisco Multicast book I know of besides Williamson's is Doyle's,
which you probably already have. But Williamson actually directly addresses
the interconnectivity between sparse and dense mcast domains (it's in the
DVMRP chapter), saying that you have to basically go dense on all of the
interfaces between your RP and your ... whatever it is that you have that
requires dense-mode flooding.
"So picture the scenario - Network A is exlcusively Sparse-mode with
statically defined RPs, Network B is a dense mode network, A user on Network A
wants to join a feed on Network B, Network B is outside Network A
configuration control. Can this realistically be achieved?"
I believe that this was the norm with the mbone for some time, I haven't been
following it in recent years, not sure where everything is status-wise
nowadays.
Check out this pdf from Cisco. If you can't run GRE over the firewall, try
GRE inside of IPSec. Kind of obeying the letter of the law, but hey, a win's
a win.
http://www.cisco.com/univercd/cc/td/doc/solution/v3pnipmc.pdf
With a few exceptions, secrecy is deeply incompatible with democracy and with
science.
--Carl Sagan
> Date: Tue, 12 Feb 2008 20:16:05 +0000
> From: ciscosurplus@gmail.com
> To: joe@affirmedsystems.com
> Subject: Re: Joining Multicast Networks of differeing Types
> CC: sadiqtanko@gmail.com; ccielab@groupstudy.com
>
> Joe,
>
> Thanks for the explanation, as you can see multicast is my bug bear! I need
> to buck my ideas up, I find it difficult and tedious, and while I know
> commands to do tasks, I guess my fundamental understanding is lacking, and
> although its no likely to encounter this on the lab, I want to try to
> understand.
>
> Still not getting the static joins all the way downstream? seems very
> mandrolic, whilst I appreciate dense mode is not in wide use, I can still
> see the need to perform this sort of operation.
>
> I mean if there we say 15 hops that infers a static join is required on
> every hop along the way.
>
> Back to the books for me, perhaps someone can reccomend an alternative to
> developming IP multicast solutions?
>
> thanks
>
> Graham
>
>
> On 12/02/2008, Joseph Brunner <joe@affirmedsystems.com> wrote:
> >
> > Urgh...
> >
> > Dense and sparse mode has NOTHING to do with the packets themselves...
> > they
> > are all still 224.0.0.0/3 DESTINATION from you guessed it a UNICAST
source
> > ip found in the routing table or the MROUTE table for the rpf check...
> >
> > The fact the interface is in sparse or dense mode means nothing to a
> > multicast packet on a interface with a static join... remember, we use
the
> > static join to get the interface into the OIL in the absence of
downstream
> > pim join...
> >
> > When you put a static join on an interface your going to SEND a PIM join
> > upstream to GET on the SOURCE TREE. Now how you get on the source tree,
> > well
> > that's the difference between Sparse mode and Dense mode... Sparse mode
> > will
> > build a shared tree to the RP, while Dense mode well, will figure things
> > out...
> >
> > So You can just run WHATEVER mode you want until a certain point, then do
> > static joins to downstream interfaces the whole way to the clients...
> >
> > Pim is smarter than sparse or dense mode... don't forget that...
> >
> > -Joe
> >
> > -----Original Message-----
> > From: Sadiq Yakasai [mailto:sadiqtanko@gmail.com]
> > Sent: Tuesday, February 12, 2008 12:32 PM
> > To: Joseph Brunner
> > Cc: graham@cisco-engineer.com; Graham Clarke; Cisco certification
> > Subject: Re: Joining Multicast Networks of differeing Types
> >
> > guys,
> >
> > so i have been thinking about this and this is what I cant get around
> > my head...did i little bit of config and still got an invalid log msg.
> >
> > At some point in trying to achieve what Graham is trying to do, there
> > has to be a segment on which one side is running sparse mode, while
> > the other is running dense mode. The two sides would ofcourse form
> > neigbour relationship (tried) but forwarding of traffic is where the
> > issue would come up!
> >
> > The side with dense mode configured wld forward traffic out the
> > interface, but the side running sparse wld not accept the traffic,
> > would it?
> >
> > Hmmm, I wonder if I correctly understood the scenario anyway?
> >
> >
>
>
> --
> Thanks
>
> Graham Clarke
>
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