From: Lei Chen (leichen@xxxxxxxxx)
Date: Tue Oct 31 2000 - 21:25:14 GMT-3
Yes. It's application to determine which group it should join. When you are
programming with ip multicasting, there is actually certain function ( like
int join(char *)) you can call with the argument of group address. If you
are using multicast applications, you should know the group addresses first
and set them up in the applications. That application simply gets the
address from you and calls the join function. This join function, socket
level, actually sends out the IGMP join message to the router.
Hope this helps...
----- Original Message -----
From: "Ronnie Royston" <RonnieR@globaldatasys.com>
To: <ccielab@groupstudy.com>
Sent: Tuesday, October 31, 2000 8:38 AM
Subject: multicasting - how does the end station know....
> I understand that end stations register with their local router via IGMP
to
> join a particular multicast group. How does the end station know what
group
> (multicast address) he wants to join? Is that learned from the
application
> he is running? Also, because the layer 3 multicast addresses are not
unique
> when mapped to the layer 2 e-net/fddi, it seems like good design practice
to
> use multicast addresses that are far enough apart to not have a problem of
> end host getting packets they do not want. Finally, if the applications
do
> in fact determine the multicast address, then how does one have control
over
> what addresses to employ?
>
> Obviously, I need a little info on how the multicast addresses are chosen,
> mapped to applications, and distributed to end stations. Any information
is
> greatly appreciated!
>
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 08:25:33 GMT-3