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What Can Effect
Videoconferencing?
A great many things, including loss. A video feed does not
need much speed, only from 128K to 3 Mbps, but any amount of
loss causes problems. H.323, the application that Parvati uses
to give her presentations, is an example of an application
family that does not tolerate loss. Loss is significant to
any real-time application, except voice. This affects remote
labs, video conferencing, and anyone trying to do high bandwidth
over long distance (because of current TCP characteristics).
There are several new high-speed TCP algorithms under development
that may fix this problem but it will be at least 3-5 years
before they are in common use. The concept of zero-packet loss
tolerance by some application families needs to be communicated
more clearly to a broad audience.
Back
to Case Study
t
is a cakebox? It is a small, inexpensive PC
running Linux. It is configured such that, when you plug it
into a DHCP-enabled Ethernet port and give it power, it registers
its presence with an LDAP server where it logs its current
IP address so you can “find” it. You can then
connect to it remotely and run a series of network utilities
(like Iperf, traceroute, and pchar). Cakeboxes were developed
by Internet2 to test H.323 video conferencing capabilities
and have been used for a variety of other end-to-end performance
tests. Instructions on “building” a cakebox are
available to member institutions upon request.
DHCP-enabled Ethernet port and give it power, it registers
its presence with an LDAP server where it logs its current
IP address so you can “find” it. You can then
connect to it remotely and run a series of network utilities
(like Iperf, traceroute, and pchar). Cakeboxes were developed
by Internet2 to test H.323 video conferencing capabilities
and have been used for a variety of other end-to-end performance
tests. Instructions on “building” a cakebox are
available to member institutions upon request.
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