Glossary 145
TRT (TokenRotation Timer). A timer in the FDDI MAC protocol that measures the
time between receipt of tokens. It expires when it reaches a value that exceeds
the TargetToken Rotation Time (TTRT).
TTRT
(TargetToken Rotation Time). A parameter in the FDDI MAC protocol that is
negotiated by all of the stations on a ring at the time a ring is broughtup. FDDI
uses the TTRT in conjunction with the TRTand THT to allocate bandwidth to
individual stations on the ring. The FDDI MAC protocol guarantees that the
worst-case delay a token will experience while circulating the ring will never
exceed twice the negotiated TTRT.