Configuring global IKE DPD

DPD detects dead peers. It can operate in periodic mode or on-demand mode.

• Periodic DPD—Sends a DPD message at regular intervals. It features an earlier detection of dead peers, but consumes more bandwidth and CPU.

• On-demand DPD—Sends a DPD message based on traffic. When the device has traffic to send and is not aware of the liveness of the peer, it sends a DPD message to query the status of the peer. If the device has no traffic to send, it never sends DPD messages. As a best practice, use the on-demand mode.

The IKE DPD works as follows:

1. The local device sends a DPD message to the peer, and waits for a response from the peer.

2. If the peer does not respond within the retry interval specified by the retry seconds parameter, the local device resends the message.

3. If still no response is received within the retry interval, the local end sends the DPD message again. The system allows a maximum of two retries.

4. If the local device receives no response after two retries, the device considers the peer to be dead, and deletes the IKE SA along with the IPsec SAs it negotiated.

5. If the local device receives a response from the peer during the detection process, the peer is considered alive. The local device performs a DPD detection again when the triggering interval is reached or it has traffic to send, depending on the DPD mode.

When DPD settings are configured in both IKE profile view and system view, the DPD settings in IKE profile view apply. If DPD is not configured in IKE profile view, the DPD settings in system view apply.

It is a good practice to set the triggering interval longer than the retry interval so that a DPD detection is not triggered during a DPD retry.

1. Enter system view.

   system-view

2. Enable sending IKE DPD messages.

   ike dpd interval interval [ retry seconds ] { on-demand | periodic }

   By default, IKE DPD is disabled.