Specifications

TOKEN RING OVERVIEW
2-26
Abort Format
This frame sequence shown in Figure 2-4 is used by a station to terminate
its transmission prematurely. The Starting Delimiter (SD) and Ending
Delimiter (ED) formats are the same as used for token and data frames.
The sequence can be detected by any station at any stage in a frame
transmission even if it does not occur in octet boundaries.
Figure 2-4. Abort Frame Structure
Token Format
A token format is the means by which the right to transmit a frame onto
the ring (as opposed to repeating) is passed from one station to another. It
is made up of three (3) fields:
• Starting Delimiter (SD) - 8 bits
• Access Control (AC) - 8 bits
• Ending Delimiter (ED) - 8 bits
The total number of bits in a token is 24.
SD ED
JK0JK
JK 1 JK E
I - 0 = last/only frame
1 = first/intermediate
E - 0 = no error detected
1 = error detected at
specific station
J = non-data J
K = non-data K
0 = zero bit
1 = one bit
SD - Starting Delimiter (one octet)
ED - Ending Delimiter (one octet)
(Both common to all frames)
000
1I