Enabling PPP link quality control
PPP link quality control (LQC) monitors the quality (packet loss ratio and packet error ratio) of PPP links (including those in MP bundles) in real time.
If PPP LQC is not enabled, each end of a PPP link sends keepalive packets to its peer periodically. After you enable PPP LQC, Link Quality Reports (LQRs) packets replace keepalive packets to monitor the link.
With PPP LQC enabled, the system monitors link quality by processing LQR packets received and shuts down the link if the link quality drops below the PPP LQC close-percentage in two consecutive LQR packet sending intervals. For a link shut down because the link quality drops below the PPP LQC close-percentage, the system detects its link quality at an interval which is ten times the LQR packet sending interval. When the link quality is higher than the PPP LQC resume-percentage in three such consecutive intervals, the system brings up the link. A shut-down link must experience at least 30 LQR packet sending intervals before it can go up again. If a long LQR packet sending interval is specified, it takes a long time for the link to go up.
To enable PPP LQC:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view. | interface interface-type interface-number | N/A |
3. Enable PPP LQC. | ppp lqc close-percentage [ resume-percentage ] | By default, PPP LQC is disabled. |
4. Configure the interface to periodically send LCP echo packets when LQC detects a low quality link. | ppp lqc lcp-echo [ packet size ] [ interval seconds ] | By default, an interface does not periodically send LCP echo packets when LQC detects a low quality link. |