Data Communications Networking Devices - 4th Ed.pdf

3.5 TOKEN-RING _________________________________________________________________ 335Figure 3.34 a) Token format P: priority bits, T: token bit, M: monitor bit, R: reservationbits); b) abort token format; c) frame formatstatus ®eld. The format of a Token-Ring frame is illustrated in Figure 3.34c). Byexamining each of the ®elds in the frame, we will also examine the token and tokenabort frames, due to the commonality of ®elds between each frame.Starting/ending delimitersThe starting and ending delimiters mark the beginning and end of a token or frame.Each delimiter consists of a unique code pattern which identi®es it to the network.Non-data symbolsUnder Manchester and Differential Manchester coding there are two possible codeviolations that can occur. Each code violation produces what is known as a nondatasymbol and is used in the Token-Ring frame to denote starting and ending