On Aug 30, 2005, at 11:59 AM, Ben Farhner wrote:
On Aug 30, 2005, at 6:40 AM, realbasic-nug-
request at lists dot realsoftware dot com wrote:
I just read that I cannot multicast over the internet
what? this wasn't in the language ref, was it? im in the process of
making a chat program with a UDP socket using multicast!
-ben
It's not a question of whether you CAN or CAN'T multicast over the
Internet.
Of course you can. If I recall, 224.0.0.0/8 is reserved for
multicast addresses.
It's just that 9:10 ISPs (and upstream routers) have multicast
routing DISABLED.
Other than MBONE I'm not aware of any major projects using multicast,
and even then I can't connect to the MBONE via Comcast since they
don't route multicast packets.
Of course, there's nothing to say that you can't use plain old UDP
instead of TCP. Especially for those packets which don't necessarily
have to arrive 100% of the time.
In fact, you may wish to use UDP for all miscellaneous traffic (such
as heartbeats and watchdogs to poll which clients are still
connected) and use TCP (client to client) for actual message
communication.
Multicast has its purposes don't get me wrong, but where you'll find
it used the most is on campus LANs and WANs ... not the Internet.
--
George M. Ellenburg, CISSP
gme30066 at comcast dot net
The Computer Security Update Podcast
<http://www.ComputerSecurityUpdate.com/>
Skype: computersecurityupdate
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