Index V

U

U reference points, 522

UART (Universal Asynchronous Receiver/ Transmitter) chip, 521

UDP (User Datagram Protocol), 521

undebug all command, 422

unicast

defined, 522

operation of, 285-286, 285

Unicast Source Address (USA), 300

unidirectional shared trees

defined, 522

for multicast traffic routing, 305, 305

uniquely identified hosts, 522

Universal Asynchronous Receiver/ Transmitter (UART) chip, 521

unnumbered frames, 522

unshielded twisted-pair (UTP) cable, 47, 522

UplinkFast, 189-190

configuring, 190-192

defined, 522

upstream information in RPF, 306-307

upstream routers, 522

USA (Unicast Source Address), 300

User Datagram Protocol (UDP), 521

user-defined frame IDs, 100

user priority in TCI, 102

UTP (unshielded twisted-pair) cable, 47, 522