In the figure, FW_A connects to FW_B through two links working in active/standby mode.

What is IKE DPD (Dead Peer Detection)?

IKE DPD (Dead Peer Detection)is a mechanism used inIPsec VPNsto check if a remote VPN peer is still reachable.

It allows the firewall to detectlink failuresandautomatically tear down and re-establish IPsec tunnelswhen necessary.

Why is DPD required in this scenario?

The network uses an active/standby link setup:

IPsec Tunnel 1 (Active) → Uses Link 1 (GE0/0/1).

IPsec Tunnel 2 (Standby) → Uses Link 2 (GE0/0/2).

IfLink 1 fails, the firewall must detect the failure andtear down IPsec Tunnel 1before establishingIPsec Tunnel 2 over Link 2.

DPD detects unreachable peersand triggers a failover.

How does IKE DPD work?

DPD periodically sends probes (HELLO messages) to the remote VPN peer.

If no response is received within a timeout period, the firewall assumes the peer is down.

Thefirewall deletes the IPsec tunnel and switches to the backup link.

Why is the answer "dpd" (lowercase)?

The questionexplicitly asks for lowercase letters.

"dpd" (Dead Peer Detection) is the correct technical term in Huawei firewalls and networking standards.

HCIP-Security References:

Huawei HCIP-Security Guide→ IPsec VPN High Availability & DPD

Huawei USG Series Firewall Configuration Guide→ IKE Dead Peer Detection (DPD)