R0106-HP MSR Router Series Interface Command Reference(V7)

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undo loopback
Default
Loopback is disabled on ISDN BRI interfaces.
Views
ISDN BRI interface view
Predefined user roles
network-admin
Parameters
b1: Places the B1 channel in external loopback.
b2: Places the B2 channel in external loopback.
both: Places both B1 and B2 channels in external loopback.
Usage guidelines
The modules with loopback-supported ISDN interfaces include 4BS (MIM), and 1BS\1BU\2BS\2BU
(SIC). In addition, loopback is also supported by the fixed ISDN interfaces on your router, if there are any.
ISDN BRI interfaces support B1 external loopback, B2 external loopback, or both.
Examples
# Place the B1 and B2 channels on BRI 2/4/0 in external loopback.
<Sysname> system-view
[Sysname] interface bri 2/4/0
[Sysname-Bri2/4/0] loopback both
mtu
Use mtu to set the MTU of a BRI interface.
Use undo mtu to restore the default.
Syntax
mtu size
undo mtu
Default
The MTU of a BRI interface is 1500 bytes.
Views
ISDN BRI interface view
Predefined user roles
network-admin
Parameters
size: Sets the MTU in bytes. The value range for this argument is 128 to 1500.
Usage guidelines
After configuring the MTU for a BRI interface, you must use the shutdown command and then the undo
shutdown command on the interface for the modification to take effect.