Cabletron Systems 9A128-01 manual SMT Version, Req. Requested Target Token Rotation Time

FDDI Management

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.

4-4 Configuration