HP 11i User Manual download pdf (Page 28)

28 Chapter3

Using HDLC/LAP-D Protocol

General Protocol Processing

Timeout Processing

Frame timeouts are set in the Select configuration word. The T200 timer

defines the period within which a response to a Command frame must be

received across the HDLC/LAP-D link. Should this timer expire before

the expected response is received, then the Command frame will be

re-transmitted up to a pre-determined maximum number of times. The

maximum number of re-transmissions (N200) is also set by the Select

configuration word. If the timer expires o n that number of s uccessive

occasions, then the LAP-D link will be reset.

An additional timer, kn own as T203 is used to control the maximum

amount of time that ca n pass without any frames being exchanged. It is

configured in the first Option word and defaults to being

T200*N200*100/16.

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HP 11i User Manual Page 28