c6h10n2o2@aol.comTospam (C6H10N2O2) writes:
> Are webcasts

This is comp.protocols.ppp. It has nothing to do with "webcasting."
You might try searching for a more appropriate newsgroup.

> simply done by really fast servers sending lots of packets to to
> lots of clients

Usually, yes.

> or is there some economy of scale that is implemented. Is there
> anything more efficient when you transmit the same data packet to lots of
> clients?

Sure; multicast. Unfortunately, it's not widely available and has all
sorts of interesting deployment problems.

> It seems to me that webcasting could never really grow large because
> it would require bandwidth linearly proportional to the number of listeners.

Not necessarily. A common approach used is to have distributed
content caches -- some are run by ISPs themselves and some are run by
third parties, such as akamai.com.

James Carlson, IP Systems Group
Sun Microsystems / 1 Network Drive 71.234W Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757 42.497N Fax +1 781 442 1677