Cabletron Systems FRM User Manual - page 97
Configuring X.25
8-9
Selecting this parameter will display a list of ranges. Press the letter corresponding to
a range to display the valid speeds within that range. All possible speeds are:
75
150
300
600
1200
2400
4800
9600
14.4K
19.2K
24K
28.8K
38.4K
48K
56K
64K
72K
112K
128K
168K
192K
224K
256K
280K
320K
336K
384K
392K
448K
504K
512K
560K
576K
616K
640K
672K
704K
728K
768K
784K
832K
840K
896K
952K
960K
1.008M
1.024M
1.064M
1.088M
1.12M
1.152M
1.176M
1.216M
1.232M
1.28M
1.288M
1.344M
1.4M
1.408M
1.456M
1.472M
1.512M
1.536M
1.568M
1.6M
1.624M
1.664M
1.668M
1.728M
1.792M
1.856M
1.92M
1.984M
2.048M
If an RS-232 DCE port is directly connected to the DTE via the standard
Cabletron cable, the maximum supported speed is 64K. If longer cabling is
used, the maximum speed is 19.2K. (The EIA standard for RS-232
addresses speeds up to 19.2 Kbps.)
Modulo
is the number of values used in X.25 level 2 sequenced packets. The actual frame num-
bering is
0–7
for modulo 8 and
0–127
for modulo 128.
Maximum LAPB Window Size
is X.25 value
K
, the maximum number of sequentially numbered I-frames that can be
waiting for acknowledgment. If this number is exceeded, no more frames will be
transmitted until an acknowledgment is received. A larger value allows faster
throughput.
N2 Retransmit Count
is X.25 value
N2
, the maximum number of times the node will attempt to send an I-
frame after a
Retransmit Period
expiration. A larger value for this parameter increases
the probability of an eventual correct transfer between DTE and DCE, but a smaller
value permits faster detection of a permanent error condition.
T1 Retransmit Period
is the length of time before re-transmission of an I-frame if the previous transmission
is not acknowledged. If the period expires, the FRM software will reset the timer and
transmit a supervisory frame demanding immediate acknowledgment. Also, the
Maximum Retransmissions
(see that entry) counter will be incremented. The default
value of
2000 ms
allows avoidance of unnecessary retransmission of frames that have
merely been delayed.
T2 Wait Ack Period
is the length of time the node will delay acknowledgment of a received I-frame if there
is no outgoing I-frame to be sent. If during this period the node receives an I-frame for
transmission, the acknowledgment will be sent with it, and the delay timer will be
reset.
T3 Link Alive Period
is the length of time after which the node will poll its counterpart if there is no data
transfer.