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3-4 The Configuration Window
SMT Version
Displays the version number of the Station Management (SMT) entity. SMT
frames have a version ID Þeld that identiÞes the structure of the SMT frame Info
Þeld. The version number is included in the SMT frame so that a receiving station
can determine whether or not its SMT version is able to communicate with the
SMT version of another station. Knowing the version number allows the station
to handle version mismatches. Each station supports a range of SMT versions.
The supported version range is identiÞed within the ietf-fddi MIB by two
smtTable attributes: snmpFddiSMTLoVersionId and snmpFddiSMTHiVersionId. If a
received frame is not within the supported version range, the frame is discarded.
SMT provides the system management services for the FDDI protocols,
including connection management, node conÞguration, error recovery, and
management frame encoding.
T-Req. (Requested Target Token Rotation Time)
The token rotation time bid made by the selected SMT entity during ring
initialization. Each station detecting that the ring must be initialized begins a
claim token process and issues a stream of Claim Frames, which negotiate the
value assigned to the Target Token Rotation Time (TTRT). The information Þeld of
these frames contains the issuing stationÕs bid for the value of TTRT. Each
claiming station inspects incoming Claim frames (from other issuing stations) and
either continues its own bid (and removes the competing Claim Frame from the
ring) or defers (halts transmission of its own bid and repeats the competing bid)
according to the following hierarchy of arbitration:
¥ A Claim Frame with the lowest TTRT bid has precedence.
¥ If the values of TTRT are equal, the frame with the longest source address
(48 vs. 16 bits) has precedence.
¥ If both TTRT value and source address length are equal, the frame with the
highest address has precedence.
The FDDI BRIM is shipped with a T-Req = 83 msec (earlier versions of Þrmware)
or 6 msec (later Þrmware versions). T-Req is stored within the MIB in units of
nanoseconds (one billionth of a second) rather than milliseconds (one thousandth
of a second); SPECTRUM Element Manager converts nanoseconds to
milliseconds for display purposes. You can use any SNMP Set Request tool to edit
the T-Req value; just remember that you must enter your value in nanoseconds,
rather than milliseconds.
T-Neg. (Negotiated)
The winning time negotiated in the ring initialization sequence.
Concentrator M Ports
This Þeld displays the number of Master (M) ports on the modular concentrator
controlled by the FDDI BRIM. A Master port is a port that provides a connection
for Single Attachment Station (SAS) devices to the FDDI network.