FAQ-A backup solution of DHCP server and VRRP

When VRRP hot standby group is used as the gateway, DHCP servers may not back up each other. Because the VRRP group does not support backup of the DHCP address pool and address allocation status, the master and slave devices are independent DHCP servers. There are problems as follows:

1. If the DHCP server and address pool are configured only on the master, the DHCP server goes down when the master is down. After the slave upgrades to the master, it cannot assign addresses to clients.

2. If the same DHCP server and address pool are configured on both master and slave devices, address conflict may occur.

You can use the following methods to solve the problem:

1. Configure CSS or iStack to virtualize two devices into one, and configure it as the DHCP server. This solution implements backup while eliminating conflicts.

2. Both master and slave devices are configured as DHCP servers, but their address pools cannot be the same. You can divide an IP address segment into two parts, with the equal number of addresses assigned to master and slave devices. This solution prevents address conflict. When the master goes down, some devices need to apply for addresses from the slave and their IP addresses may change. Ensure that there are sufficient addresses for clients to apply for.

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