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FDDI Management
4-4 Configuration
to remove from the ring and conduct a self-test. If the
ring does not recover, each subsequent upstream station
will be forced to remove from the ring and conduct
self-tests until the problem has been corrected. While the
test is being conducted, ring management re-enters the
isolated state.
SMT Version
Displays the version number of the Station Management (SMT) entity. SMT
provides the system management services for the FDDI protocols, including
connection management, node configuration, error recovery, and management
frame encoding. SMT frames have a version ID field that identifies the structure
of the SMT frame Info field. 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 stations to handle version mismatches. Each FDDI station
supports a range of SMT versions. The supported version range is identified
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.
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 field of
these frames contains the issuing station’s 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 9A128-01 is shipped with a T-Req = 83 msec (earlier versions of firmware) or
6 msec (later firmware 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.