Command Reference Guide

3Com Router 5000 Family and Router 6000 Family isdn crlength ● 179
Command Reference
isdn crlength
Purpose Use the isdn crlength command to set length of the call reference used when a
call is placed on an ISDN interface.
Use the undo isdn crlength command to restore the default ISDN call reference
length on the interface.
Syntax isdn crlength call-reference-length
undo isdn crlength
Parameters call-reference-length
ISDN call reference length, which can be one or two
bytes.
Default By default, the call reference length is two bytes for E1 PRI and T1 PRI interfaces and
one byte for BRI interfaces.
Example Set the call reference length carried by the ISDN messages on the PRI interface
serial0/0/0:15 to 1 byte.
[3Com-serial0/0/0:15] isdn crlength 1
View This command can be used in the following views:
■ ISDN Interface view
Description Call reference is equal to the sequence number that the protocol assigns to each call.
It is one or two bytes in length and can be used cyclically.
When the router receives a call from a remote device, it can automatically identify the
length of the call reference. However, some devices on the network do not have such
capability. In the event that the router is required to place calls to such a device
connected to it, you must configure the router to use the same call reference length
configured on the connected device.
You are not allowed to configure this command on an ISDN interface if there is still a
call on it. This command can take effect only if it is configured when there is no call
on the interface. Alternatively you can manually disable the interface by executing the
shutdown command, configure the command, and then enable the interface by
executing the
undo shutdown command. The operations, however, will lead to the
disconnection of the call existing on the interface.