Nortel Networks Video Gaming Accessories 553-3001-211 Manual De Usuario

Appendix A: LAPB Data Link Control protocol

Applications which use ports on the QPC513 are automatically designated as 
BAC, 2, 8 (for example, balanced operation, asynchronous balanced mode 
class of procedure with optional functions 2 and 8 implemented).

A balanced configuration is one in which two combined stations have 
identical responsibilities for exchanging data and control information and for 
initiating error recovery functions, as shown in Figure 188 on 

. 

A combined station has balanced link control capability and transmits both 
commands and responses to, and receives both commands and responses 
from the other combined station.

01111110

8 bits

8 bits

unspecified 

(no. of bits)

16 bits

01111110

Flag: Flag sequence – All frames start and end with the flag sequence. (A single flag is used as both the 
closing flag for one frame and the opening flag for the next frame.)

Address: Station address field – In command frames, the address identifies the station for whom the 
command is intended. In response frames, the address identifies the station from which the response 
originated.

Control: Control field – This field contains commands or responses and sequence numbers.

Information: Information field – Information may be any sequence of bits, usually related to a convenient 
character structure such as an octet, but may be an unspecified number (from 1 to 128) of bits unrelated to 
a character structure.

FCS: Frame check sequence.