Enterasys Networks CSX6000 - Manual (Page 248)

USER’S GUIDE
248 CyberSWITCH
B EARER C HANNELS
A list of bearers (a channel map) that will be used on the line associated with this X.25 access. For
PRI lines, the range of channels is from 1 to 24.For BRI lines, the range of channels is from 1 to 2.
Separate bearer channels by commas, and/or list a range by using a dash (-).
LAPB C ONFIGURATION E LEMENTS
Link Access Protocol-Balanced (LAPB), is a data link layer protocol that is used in X.25 connections.
LAPB is based on the HDLC protocol.
Note: If you are unsure of any of these values, use the default values where provided.
LAPB S EQUENCE N UMBER R ANGE
The LAPB sequence number range to use, regular, or extended. Extended sequence numbering
allows for frames to be assigned sequence numbers from 0-127 (modulo 128), as opposed to 0-7
(modulo 8). Using modulo 128, the DTEs can send up to 127 frames without receiving an
acknowledgment. Using modulo 8, the DTEs can send up to 7 frames without receiving an
acknowledgment. The default value is modulo 8.
T IMER T1
This timer defines the maximum time to wait for responses to pending commands. The range for
the T1 timer is 1 to 10 seconds. The default value is 1 second.
T IMER T3
This timer signals that an excessively long idle time is occurring on the link. LAPB requires that
Timer T3 be greater than Timer T1. The range for the T3 timer is 2 to 20 seconds. The default value
is 10 seconds.
M AXIMUM N UMBER OF F RAME R ETRANSMISSIONS
This is the maximum number of frame retransmissions that can be performed (commonly known
as “N2”). If this maximum is exceeded, the link is considered out of order. The range for the
maximum number of frame retransmissions is 1 to 5 retransmissions. The default value is 3
retransmissions.
M AXIMUM NUMBER OF O UTSTANDING F RAMES
Enter the maximum number of frames that the transmitting station may have outstanding at any
given time (commonly known as “K”). The range for this parameter will be 1-7 if the modulo 8
sequence numbers are being used for LAPB, or 1-127 if modulo 128 sequence numbers are being
used. The range for the maximum number of outstanding frames is 1 to 7 frames. The default value
is seven frames.