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RATE ADAPTION
T-LINK
To allow greater flexibility for your DTE, three rate adaption
protocols are available for use on the B-channel: T-Link,
V.120, and Bonding (see Chapter 10 for a description of
Bonding). These protocols allow your DTE to operate both
synchronously and asynchronously, and at a different speed
than the B-channel.
When a data call is placed, the TA tries to establish physical
data connection on the ISDN B-channel. The B-channel is a
digital channel that can transfer data at 56 or 64 kbps,
depending on the path the network chooses when routing the
call.
A rate adaption protocol is necessary if the user's DTE rate is
other than 56 or 64 kbps. The protocol adapts the lower speed
of the DTE to the higher speed of the ISDN B-channel. The
LCD menu or the AT%A2 command can be used to select a
rate adaption protocol.
This chapter discusses two rate adaption protocols: TLink and
V.120.
• T-Link does not guarantee error free data; it only adapts the
lower DTE speed to the higher ISDN speed to a maximum
of 19.2 kbps asynchronous and 64 kbps synchronous.
• V.120 is an error-controlling protocol that guarantees error
free data transfer at speeds up to 128 kbps. (Throughput is
limited by the B-Channel to about 70 kbps.)
T-Link is a Northern Telecom proprietary rate adaption
protocol. It supports synchronous and asynchronous rate
adaption at a variety of speeds.
To select T-Link with the LCD, scroll through the menu and
select:
• CONFIGURATION OPTIONS?
• PORT CONFIG OPTIONS?
• PROTOCOL OPTIONS?
• PROTOCOL = T-LINK
To select T-Link with the AT%A2 command, enter
AT%A2=1.
UTA220/UTA220k
Rate Adaption
Chapter 9
Rate Adaption
9-1
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