From: keith tokash (ktokash@hotmail.com)
Date: Wed May 21 2008 - 15:33:18 ART
If I understand this correctly, PC1 and PC2 will both be the sources for those
applications, with a third PC (PC3) joining the 239.1.1.1 group. That may
very well whack both applications (unless the application is smart enough to
distinguish between the streams, and powerful enough to keep up), and is
actually a reason source-specific multicast was contrived.
http://www.cisco.com/en/US/docs/ios/12_4/ip_mcast/configuration/guide/mcbbasi
c.html#wp1127486
"
In the ISM service, applications must acquire a unique IP multicast
group address because traffic distribution is based only on the IP
multicast group address used. If two applications with different
sources and receivers use the same IP multicast group address,
receivers of both applications will receive traffic from the senders of
both applications. Even though the receivers, if programmed
appropriately, can filter out the unwanted traffic, this situation
would cause generally unacceptable levels of unwanted traffic."
Cisco is using the term "ISM" to describe PIM-SM + MSDP. I actually had to
google that term a couple of days ago when a developer hit me with it. I
groaned, thinking it was another server guy talking to me about his
"sparse-mode application" and other sordid nonsense, but they actually do use
that term. Just in that spot I think, but they do use it.
With a few exceptions, secrecy is deeply incompatible with democracy and with
science.
--Carl Sagan
> Date: Tue, 20 May 2008 10:13:27 +1000
> From: pbhatkoti@gmail.com
> To: ccielab@groupstudy.com
> Subject: stupid quesiton - multicast
>
> Scenario:
>
> PC1----------R1----s0---WAN-L2------s1------R2----------PC2
>
> PC2 is running Multicast application on 239.1.1.1 port 16400
>
> What will happen if I assign 239.1.1.1 port 16400 mcast address on PC1
> application as well?
> Assuming that M.cast routing is enabled on both routers and on each
> interfaces.
>
> 1. Do we have IP address conflict in Mcast address as well?
> 2. When I have 2 application in the PC2 - application1 & application2
> application1: 239.1.1.1 port 16400
> application2: 239.1.1.2 port 16400
> The first application works but, the second one doesn't.
>
> But If I change it to
> application1: 239.1.1.1 port 16400
> application2: 239.1.1.9 port 16400
>
> Both applications works!
>
>
> I couldn't figure out why it won't work like class a/b/c IP address. I what
> is the rule in Mcast addressing?
>
>
>
> -frog
>
>
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