EMC Connectrix B Series Hardware Reference Manual page 116

Glossary
TTL Time-to-live. The number of seconds an entry exists in cache before it
expires.
Tunneling A technique for enabling two networks to communicate when the
source and destination hosts are both on the same type of network,
but are connected by a different type of network.
TX Transmit.
U
U_Port Universal port. A switch port that can operate as a G_Port, E_Port,
F_Port, or FL_Port. A port is defined as a U_Port when it is not
connected or has not yet assumed a specific function in the fabric.
UDP User Datagram Protocol. A protocol that runs on top of IP and
provides port multiplexing for upper-level protocols.
ULP
Upper-level Protocol. The protocol that runs on top of Fibre Channel.
Typical upper-level protocols are SCSI, IP, HIPPI, and IPI.
ULP_TOV Upper-level time-out value. The minimum time that a SCSI ULP
process waits for SCSI status before initiating ULP recovery.
Unicast The transmission of data from a single source to a single destination.
See also Broadcast and Multicast.
User Account A login intended for use by the customer to monitor, but not control,
switch operation.
UTC Universal Time Conversion. Also known as "Coordinated Universal
Time," which is an international standard of time. UTC is 8 hours
behind Pacific Standard Time and 5 hours behind Eastern Standard
Time. See also GMT.
V
VC Virtual circuit. A one-way path between N_Ports that allows
fractional bandwidth.
W
WAN Wide area network.
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EMC Connectrix B Series DS-8B3 and DS-16B3 Hardware Reference Manual