R3303-HP HSR6800 Routers Layer 2 - WAN Command Reference

ppp lqc

Use ppp lqc to enable PPP link quality control (LQC).

Use undo ppp lqc to disable PPP LQC.

Syntax

ppp lqc close-percentage [ resume-percentage ]

undo ppp lqc

Default

PPP LQC is disabled.

Views

Interface view

Default command level

2: System level

Parameters

close-percentage: PPP LQC close-percentage, in the range of 0 to 100.

resume-percentage: PPP LQC resume-percentage, in the range of 0 to 100.

Usage guidelines

The default value of the resume-percentage argument is equal to the value configured for the

close-percentage argument. The value of the resume-percentage argument, if configured, must be

greater than or equal to that of the close-percentage argument.

LQC monitors the quality (packet loss ratio and packet error ratio) of PPP links (excluding MP bundles) in

real time.

If PPP LQC is not enabled, each end of a PPP link periodically sends keepalive packets to its peer. If PPP

LQC is enabled, Link Quality Reports (LQRs) packets replace keepalive packets to monitor the link.

The system uses received LQR packets to measure the link quality. If two consecutive measured results are

below the close-percentage, the system shuts down the link. Then the system measures the link quality at

an interval that is ten times the LQR interval. If three consecutive measured results are higher than the PPP

LQC resume-percentage, the system brings up the link.

A shut-down link must experience at least 30 keepalive intervals before it can go up again. If you set a

large keepalive interval, the link will take a long time to come up.

If you enable PPP LQC on both sides of a PPP link, make sure both sides have the same PPP LQC settings.

Typically, there is no need to enable PPP LQC on both sides of a PPP link.

H3C recommends that you not enable PPP LQC on a DDR dial-up link because DDR tears the link down

when the link is closed by LQC. Then LQC cannot send LQR packets to resume the link.

Examples

# Enable PPP LQC on interface Serial 2/1/1, and set the PPP LQC close-percentage to 90 and

resume-percentage to 95.

<Sysname> system-view

[Sysname] interface serial 2/1/1

[Sysname-Serial2/1/1] ppp lqc 90 95