Cyclades AlterPath BladeManager user manual Udp, Rack Height Unit

Glossary
UDP	User Datagram Protocol uses a special type of packet called
	a datagram. Datagrams do not require a response; they are
	one way only (connectionless). Datagrams are usually used
	for streaming media because an occasional packet loss will
	not affect the final product of the transmission.
U Rack Height Unit	A standard computer rack has an internal width of 17 inches.
	Rack space on a standard rack is measured in units of height
	(U). One U is 1.75 inches. A device that has a height of 3.5
	inches takes 2U of rack space.

Glossary-12 AlterPath Manager E2000 Manual