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The following parameters for configurable for HDLC/LAP-D links: - SAPI
The Service Access Point Identifier - TEI
The Terminal Endpoint Identifier - U/N
Operating mode - User or Network side - K
Number of outstanding I frames - N200
Number of retransmissions allowed - N201
Largest I-field allowed (in bytes) - T200
Acknowledgment Timer - T203
Idle line Timer - UI
Unnumbered Information terminal
T200 and T203 are configured by selecting a value (Val) and
a resolution (Res). Val can range from 1 to 31 and Res selects either
10 msec, 100 msec, 1 sec or 10 sec resolution. For a given Val and
Res, the configured value is (2*Val Res). The actual timeout
period however, may occur up to one Res before the configured value.
The following table shows the minimum and maximum timeouts for various
combinations of Res and Val. Val | Res | Minimum
Timeout | Maximum
Timeout |
|---|
1 | 10 msec | 10 msec | 20 msec | 2 | 10 msec | 30 msec | 40 msec | 31 | 10 msec | 610 msec | 620 msec | 1 | 100 msec | 100 msec | 200 msec | 4 | 100 msec | 300 msec | 400 msec | 31 | 100 msec | 6100 msec | 6200 msec | 1 | 1 sec | 1 sec | 2 sec | 8 | 1 sec | 15 sec | 16 sec | 31 | 1 sec | 61 sec | 62 sec | 1 | 10 sec | 10 sec | 20 sec | 16 | 10 sec | 310 sec | 320 sec | 31 | 10 sec | 610 sec | 620 sec |
When choosing values for timers, it is preferable to choose
the resolution that has the longest interval but is still suitable
for your application. Poll Word | |
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
U/N | UI | N201 (1-16383 bytes) See
note below |
U/N | Configure port as user or network side:
0
= Port to act as network side
1 = Port to act as user side | UI | Configure terminal as a UI (Unnumbered
Information) terminal:
0 = Terminal is not a UI terminal
1
= Terminal is a UI terminal | N201 | Maximum number of bytes in the largest
acceptable I field. Values from 1 to 16,383. |
Select Word | |
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| T200 Res | T200 Val (I-63) | K (0-7) | N200 (1-31) |
T200 Val | This is the value of the T200 Acknowledgment
timer divided by two. The valid range for this field is 1 to 63
which translates to T200 timer values of 2 to 126. 0 is not allowed
and is an error. The units of this timer are given by the T200 Res
(resolution) field (see below). Before configuring T200, you should
read the description of timer configuration at the beginning of
this section. | T200 Res | Resolution of T200 Val above. The values
correspond as follows: | 0 = 10 milliseconds | | 1 = 100 milliseconds | | 2 = 1 second | | 3 = 10 seconds |
| K | Level 2 window size, values 1 to 7. Note
that if 0 supplied, the LargeK value in the first option word is
used. It is an error if both K and LargeK are 0. | N200 | Number of retransmissions, values 1 to
31. Note that 0 is not allowed and is an error. |
First Option Word | |
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
T203 Res | T203/2 Val (0-63) | IUF | LargeK (0-127) |
T203 Val | This is the value of the T203 Idle line
timer divided by two. Setting this field from 1 to 63 translates
to T203 timer values of 2 to 126. The units of this timer are given
by the T203 Res (resolution) field (see below). If a value of zero
is given for both this field and T203 Res, a default value of approximately T200*N200*100/16
will be used for a user-side terminal. (The default for a network-side
terminal is T203 disabled.) If T203 Res is non-zero but this field
is zero, T203 will be disabled. Before configuring T200, you should
read the description of timer configuration at the beginning of
this section. | T203 Res | Resolution of T203 Val above. The values
correspond as follows: | 0 = 10 milliseconds | | 1 = 100 milliseconds | | 2 = 1 second | | 3 = 10 second |
| IUF | Error handling, normal when 0. This means
normal error handling (level 2 link reset) on receipt of unsolicited
response frame with F=1. 1 means Ignore F=1 (treat as F=0) in any unsolicited
response frames. | LargeK | Level 2 window size, values 1 to 127.
LargeK is only used if K in the Select Word is 0. It is an error
if both K and LargeK are 0. |
Second Option Word | |
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
0 | SAPI | 0 | TEI |
0 | Unused - should always be zero. | SAPI | The Service Access Point Identifier. | TEI | This value is used as the Terminal Endpoint
Identifier. |
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