Specifications

2-23
TOKEN RING OVERVIEW
Claim Token Process (CL_TK)
All stations are capable of being the AM, while others remain as SMs. The
establishment of an AM is achieved by a Ring Station (RS) detecting the
absence of an AM and originates a Claim Token, also known as Monitor
Contention. The conditions on which a Claim Token MAC frame are
issued are when either the standby monitors Good Token Timer or
Receiver Poll timers have expired.
Duplicate Address Test (DAT)
Upon initialization of a workstation a DAT frame is transmitted by that
station. The physical address of the station is placed in the DA field, if any
other station on the network has the same address it sets the Address
Recognized bit. When this occurs the network management station is
informed and that station is denied access to the ring.
Active Monitor Present (AMP)
The Active Monitor (AM) transmits this frame to notify all other stations
that an AM is present on the ring. If the AMP frame is not received by the
SMs within seven (7) seconds or after a Ring Purge, the Claim Token frame
is issued by the SM.
Standby Monitor Present (SMP)
Standby Monitors (SM) respond to AMP or other SMP frames during the
Neighbor Notification process.
Beacon (BCN)
Any station transmits a BCN when a wire fault is detected, signal has been
lost, or a station is streaming. The BCN notifies the station’s NAUN to test
its receiver, transmitter, and lobe cabling.
Ring Purge (PRG)
The AM transmits this frame after the Claim Token MAC frame or when
there has been a frame received with the M bit still set.
Change Parameters (CHG_PARM)
Utilized by the CRS to set ring operational values.
Initialize Ring Station (INIT)
The RPS transmits this frame in response to a Request Initialization MAC
frame received by a station. This frame provides the correct operational
parameters to the station.
Lobe Media Test (TEST)
This frame is used by the individual during the Ring Initialization process.
It tests the continuity and bit error rate of the station lobe cabling.