Index U

[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W]

UDLD (Unidirectional Link Detection)  2nd  3rd  4th 
    compared to Loop Guard  2nd 
UDP
    multicasts 
underrun (IP telephony) 
unicasts  2nd 
Uninterruptible Power Supply.   [See UPS]
uplink interfaces
    Layer 2 redundancy  2nd  3rd 
UplinkFast (STP)  2nd  3rd  4th 
UPS (Uninterruptible Power Supply)
    importance of 
    IP telephony 
username command
    AAA and