HP Advanced Communications Controllers (ACC) manual Timeout Processing

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 on that number of successive occasions, then the LAP-D link will be reset.

An additional timer, known as T203 is used to control the maximum amount of time that can pass without any frames being exchanged. It is configured in the first Option word and defaults to being T200*N200*100/16.

28 Chapter 3