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Administering FDDI MACs 8-9
Setting maxT-Req The maxT-Req attribute specifies the maximum time value of fddiMACT-Req
that will be used by any MAC that is configured onto this path. T-Req is the
value that a MAC bids during the claim process to determine a ring’s
operational token rotation time, T_Opr. The lowest T-Req bid on the ring
becomes T_Opr.
When T_Opr is a low value, the token rotates more quickly, so token latency
is reduced. However, more of the ring’s available bandwidth is used to
circulate the token. Higher values of T_Opr use less bandwidth to circulate
the token, but they increase token latency when the ring is saturated.
To set maxT-Req:
1 From the top level of the Administration Console, enter:
fddi path maxTreq
You are prompted for a station, path, and value. The Switch 2200 has one
station, which appears in brackets.
2 Press [Return].
3 Enter the path (
p = primary, s = secondary).
4 Enter the new minimum time value.
The default value is 165000 microseconds (µs)
See the following example:
Select station [1]:
Select path(s) (p,s,|all) [p]:
Station 1 Primary - Enter new value [165000]:
Administering
FDDI MACs
An FDDI MAC uses a token-passing protocol to determine which station has
control of the physical medium (the ring). The primary purpose of the MAC
is to deliver frames (packets) to their destination by scheduling and
performing all data transfers. You can display MAC statistics and configure
the following parameters:
■ MAC FrameErrorThreshold
■ NotCopiedThreshold
■ Logical Link Control (LLC) service
Top-Level Menu
system
ethernet
➧fddi
bridge
ip
snmp
analyzer
script
logout
station
➧path
mac
port
display
tvxLowerBound
tmaxLowerBound
➧maxTreq