The TCP/IP protocol provides an error-free data connection by resending any packets that become lost or mangled in transmission. The resends introduce delays, which can cause noise or skipped frames. Therefore, media players prefer the UDP protocol when itÍs available. The theory is that dropping a packet occasionally is better than the delay induced by retransmittal with TCP/IP.
UDP is often blocked at firewalls and routers. If you have a gateway router such as a Linksys or Asante, check to make sure it allows UDP through on ports 6970-6999. If UDP is unavailable, the player will next try to use TCP/IP on the default port.
Firewalls often block the high port numbers. If the default media port is blocked, the player checks port 80. All of the servers reviewed here allow streaming on port 80, though it must be explicitly enabled. ThatÍs because streaming on port 80 precludes the server from using it for normal HTTP services.
If you run a corporate firewall and your users frequently use media streams, you might want to consider opening ports for UDP streaming. It should reduce the load on your network and will result in higher-quality streaming.