3Com REMOTE ACCESS SYSTEM 1500, Management Manual

Page: 154 / 300

152 C
HAPTER
10: A
DVANCED
M
ODEM
C
ONFIGURATION WITH
CLI/AT
COMMANDS
Disabling V.34
Connections
The RAS 1500 allows the selective disabling of V.34 connections
depending on whether or not they are made with an x2 capable modem
(Table 42).
Table 42 Disabling V.34 Connections
S-Register S76, bit 3 can be set only via AT commands at this time.
Configuring ISDN
The RAS 1500 supports X.75 frame and window size configuration.
Enabling X.75 To enable X.75, set S68=0.
Frame Size Frame size is the number of data bytes sent in an X.75 frame.
Window Size Window size is the number of frames sent before an acknowledge (ACK)
is received.
Window size is an important consideration in the performance of the
system. The larger the window, the more frames that can be transferred
without an acknowledgment. However, the more frames that are
transferred without an acknowledgment, the more the receiver is
required to allocate additional buffer space to handle the incoming
transmissions.
Selecting Frame and
Window Size
Use the following AT commands to select frame and window size:
Action Command
Allow V.34 and x2 connections ATS54.7 = 0
Allow V.34 and x2 connections only with x2
modems ATS56.6 = 0 (for x2 modems
only)ATS56.7 = 1ATS27.2 =
1ATS13.5 = 1
Allow V.34 connections to all modems ATS56.6 = 0ATS76.3 = 0
Disable V.34 and x2 connections to all
modems ATS54.7 = 1
Disable V.34 connections to non-x2 modems,
but allow V.34 connections to x2 modems ATS56.6 = 1ATS76.3 = 0
Disable V.34 connections to x2 modems ATS56.6 = 0ATS76.3 = 1
Disable V.34 connections, but allow x2
connections to all modems ATS56.6 = 1ATS76.3 = 1