Configuring link status polling
An HDLC-enabled interface can regularly check link status by sending keepalives to the peer at the keepalive interval at the link layer. A keepalive carries the local sender sequence number and the last received sequence number of the peer.
After sending a keepalive, an interface increments the sender sequence number by 1 in the next keepalive when the following conditions exist:
The interface receives a response within the keepalive interval.
The response carries the sender sequence number in the sent keepalive.
After sending a keepalive, if the interface does not receive a response within the keepalive interval, it resends the keepalive with an unchanged sequence number. When the keepalive retry limit is reached, the interface considers the link faulty and reports a link layer down event.
When you configure link status polling, follows these restrictions and guidelines:
Link status check is disabled if you set the keepalive interval to 0.
As a best practice, set the same keepalive interval for the two ends of a link.
If the network has a long delay or is experiencing congestion, you can increase the keepalive interval to prevent the link from being closed.
To configure link status polling:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view. | interface interface-type interface-number | N/A |
3. Set the keepalive interval. | timer hold seconds | By default, the keepalive interval is 10 seconds. |
4. Set the keepalive retry limit. | timer-hold retry retries | By default, the keepalive retry limit is 5. |