How to broadcast / multicast messages?

How to broadcast / multicast messages?

Post by Roland Geie » Sat, 02 Dec 1995 04:00:00



Hi!

I have written a tcp-server that is concurrently connected to several remote
clients.  Our network-topology is Ethernet. Some of the clients could be
grouped into logically connected subgroups to which I'd like to send multicast
messages to avoid sending a seperate message to each single client of the
subgroup.

All I know so far about the subject ist that the underlying network-hardware
determines the availabilty and 'howto' of broadcast and multicast services.
Perhaps anyone could give me some more informations or references to
literature.

Any help is appreciated!

--- Roland.

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 Roland Geier                         Universitaet Passau, Ger
                                      Lehrstuhl Prof. Dr. Donner

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How to broadcast / multicast messages?

Post by Marek Gmyr » Sat, 02 Dec 1995 04:00:00


: I have written a tcp-server that is concurrently connected to several remote
: clients.  Our network-topology is Ethernet. Some of the clients could be
: grouped into logically connected subgroups to which I'd like to send multicast
: messages to avoid sending a seperate message to each single client of the
: subgroup.

Multicast is currently not supported by TCP/IP protocol (extended/new protocol
is being developed, it is supposed to support multicast, but it is a future).
If you insist on doing this you have to implement it by yourself (eg. server
could have structures reflecting your network topology).

: All I know so far about the subject ist that the underlying network-hardware
: determines the availabilty and 'howto' of broadcast and multicast services.
: Perhaps anyone could give me some more informations or references to
: literature.

Broadcast <> Multicast. Broadcasting means sending data to all hosts on a
network. Ethernet supports broadcasting. You can broadcast data only on
one physical network - you can not hop over a router. Broadcasting is
provided only for datagram sockets in TCP/IP, so you can not use is with
your tcp client/server.

Marek.