4000 Router Series Interface Command Reference

Predefined user roles

network-admin

Parameters

hdlc: Specifies the HDLC link layer protocol.

ppp: Specifies the PPP link layer protocol.

Examples

# Configure the link layer protocol of Serial 2/0 as hdlc.

<Sysname> system-view

[Sysname] interface serial 2/0

[Sysname-Serial2/0] link-protocol hdlc

loopback

Use loopback to enable loopback on the serial interface.

Use undo loopback to restore the default.

Syntax

loopback

undo loopback

Default

Loopback is disabled.

Views

Asynchronous interface view, synchronous/asynchronous interface view

Predefined user roles

network-admin

Usage guidelines

Loopback is intended for test use. Disable loopback in other cases.

Examples

# Enable loopback on interface Serial 2/0.

<Sysname> system-view

[Sysname] interface serial 2/0

[Sysname-Serial2/0] loopback

# Enable loopback on interface Async 6/4/0.

<Sysname> system-view

[Sysname] interface async 6/4/0

[Sysname-Async6/4/0] loopback

mtu

Use mtu to set the MTU for an interface.

Use undo mtu to restore the default.