Northern UTA220/UTA220k manual 120, Options

Rate Adaption

V.120

V.120 is a CCITT protocol that supports synchronous and asynchronous rate adaption, and also provides link-layer error control. Although errors on a digital network are rarer than on an analog telephone line, they are possible. V.120 provides an end-to-end protocol for detecting and correcting any such errors. V.120 also performs buffering and can thus support flow control to and from the DTE.

To select V.120 with the LCD, scroll through the menu and select:

•CONFIGURATION OPTIONS?

•PORT CONFIG OPTIONS?

•PROTOCOL OPTIONS?

•PROTOCOL = V.120

To select V.120 with the AT%A2 command, enter AT%A2=2.

V.120 Options

Maximum Transmit Frame Size is the maximum size a frame can be for transmitting. The transmit frame size affects the store-and-forward delay.

Maximum Receive Frame Size is the maximum size frame that is accepted by the TA. Larger frames are rejected.

Window Size is the number of frames that can be sent before an acknowledgment is received. This parameter is normally not changed.

T200 Timer is the length of time to wait for acknowledgment of a sent frame. If this timer expires, V.120 attempts to send the frame again.

UTA220/UTA220k 9-3