Configure association between DHCP and IP-link on a USG firewall.
To ensure network reliability, some enterprises use the dual-uplink networking. Usually, the DHCP link serves as the active link. In such a case, the egress gateway of the enterprise serves as the DHCP client, and the enterprise obtains IP addresses from the DHCP server to access the Internet. A link such as a 3G or PPPoE link serves as the standby link.
As the DHCP client, the egress gateway cannot detect the availability of the link behind the DHCP server. If the link fails, the gateway cannot switch the service traffic to the standby link rapidly, resulting in service interruptions.
Association between DHCP and IP-link solves this problem. IP-link monitors the validity of the link behind the DHCP server and dynamically determines the availability of the DHCP access link.
Key configurations for association between DHCP and IP-link on a USG firewall:
# Enable IP-link.
[USG] sysname USG_A
[USG_A] ip-link check enable
# Create IP-link 1 for detecting link reachability from the USG to 126.96.36.199.
[USG_A] ip-link 1 destination 188.8.131.52 interface GigabitEthernet 0/0/1 mode icmp next-hop dhcp
Configure the DHCP client and associate DHCP with the IP-link.
# Enable the DHCP client function on GigabitEthernet 0/0/1 and associate DHCP with IP-link 1.
[USG_A] dhcp enable
[USG_A] interface GigabitEthernet 0/0/1
[USG_A-GigabitEthernet0/0/1] dhcp client enable track ip-link 1[USG_A-GigabitEthernet0/0/1] quit