4000 Router Series Interface Command Reference

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 is any.

ISDN BRI interfaces support B1 external loopback, B2 external loopback, or both.

Examples

# Place the B1 and B2 channels on interface BRI 1/0 in external loopback.

<Sysname> system-view

[Sysname] interface bri 1/0

[Sysname-Bri1/0] 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: MTU of the current interface, in the range of 128 to 1500 bytes.

Usage guidelines

To validate your MTU setting, shut down and then bring up the interface with the shutdown and undo

shutdown commands.

Examples

# Set the MTU of the BRI interface BRI 1/0 to 1430 bytes.

<Sysname> system-view

[Sysname] interface bri 1/0

[Sysname-Bri1/0] mtu 1430