4000 Router Series Interface Command Reference

Usage guidelines

If the upper layer protocol of an interface is PPP, FR, or HDLC, the link layer sends keepalive packets to

the peer. If it cannot receive any keepalive packets sent by the peer, the link layer considers the peer is

faulty and shuts down the interface. You can use this command to modify the interval at which the

interface sends keepalive packets.

Configure a reasonable value for the interval on a low-speed link. A too small value might cause frequent

interface shutdown because keepalive packet sending and receiving might be delayed when large

packets are transmitted.

Examples

# Set the polling interval to 15 seconds for interface serial 2/0.

<Sysname> system-view

[Sysname] interface serial 2/0

[Sysname-Serial2/0] timer-hold 15

Synchronous, asynchronous, and

synchronous/asynchronous serial interface

configuration commands

async-mode

Use async-mode to set the operating mode for an asynchronous serial interface.

Use undo async-mode to restore the default.

Syntax

async-mode { flow | protocol }

undo async-mode

Default

An asynchronous serial interface operates in protocol mode.

Views

Asynchronous serial interface view, synchronous/asynchronous interface view

Predefined user roles

network-admin

Parameters

flow: Configures the interface to operate in flow mode, or interactive mode. In this mode, the two ends

interact attempting to set up a link after the physical link is set up. During this process, the calling party

sends configuration commands to the called party (this is equal to the operation of manually inputting

configuration commands at the remote end), sets the link layer protocol operating parameters of the

called party, and then sets up the link. This approach applies to man-machine interactions such as dial-in

access.