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Match.speed
Option Values: on, off
Applicable Data Protocols: Mode 2
This option permits endpoints running at different speeds to communicate via the Mode 2
protocol. To establish a Mode 2 data call both endpoints must be at the same speed or the
Match.speed option must be on at the endpoint with the higher speed.
The terminal adaptor connected to the higher-speed endpoint buffers up the data and meters it
toward the network at the rate of the lower-speed endpoint, and controls the data flow from the
attached equipment using the Trans.flow control mechanism. If Trans.flow is off or if the
attached terminal does not support Flow Control, you are likely to lose data. Mode 2 protocol
does not provide an end-to-end flow control mechanism for connection of endpoints with
mismatched speeds. The lower speed endpoint must not send xon/xoff characters to control the
flow of the high speed endpoint because these flow control characters become mixed with any
xon/xoff characters sent to the higher speed endpoint generated locally by the higher speed
ADM. If this condition occurs, data will be lost because two independent entities (the local
ADM and the remote endpoint) are trying to control the higher speed endpoint simultaneously.
If the conditions in the above paragraph cannot be met, then Mode 3 or V.120 are the
recommended data protocols.
When Match.speed is set to off, a Mode 2 call to another endpoint can only be established if the
other endpoint is running at the same speed. Other data modes use bidirectional flow techniques
to connect endpoints of dissimilar speeds.
Min.timer (Minimum Delay Timer)
Option Values: on, off
Applicable Data Protocols: X.25, Mode 3, BV64I, and BV56I
Turning on this option optimizes packet data transmission initiated from either a person typing
or from a computer.
If characters received from the attached data equipment are separated in time by more than
approximately 10 milliseconds, then packets are transmitted to the network without artificial
delay. This is the case for a person typing.
If characters are received more closely spaced in time than as described above, characters are
assembled into packets. This may be the case of a computer answering a data base query or
transferring a file. In general, the size of the packet equals the number of characters received
prior to a gap in the reception or a full packet, whichever is less. An exception to the above
occurs when the first packet after a gap is transmitted. This packet may contain fewer characters
(possibly only one character).
Interaction with Idle.timer: An Idle timer value greater than .05 seconds takes precedence
over the Min.timer.
4-10
Data Options and Profiles
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