Configure DHCP Cluster question

Question

Dear All,

         I have a question would like to ask as currently i have 2 x dhcp server (192.168.1.13 & 14) serving different dhcp ranges and they are not running in dhcp cluster, and one of the dhcp server (192.168.1.13) serving ip segment 192.168.12.100 - 200 in vlan 200 for wifi with cisco router having ip helper 192.168.1.13, and in dhcp option 43 binary (192.168.1.57) the wireless controller ip address, what i planning to do now is to create a dhcp cluster in the current 2 x dhcp server, i will be using vip 192.168.1.15, it will be using same dhcp range as cluster, in this case the cisco router ip helper address will be change to 192.168.1.15, and in dhcp option 43 binary will be remain as 192.168.1.57, may i ask does it looks fine above ? any help would be appreicated 

Keith

Answer 1

Hello

Thank you for posting in Microsoft Community forum.

The DHCP server configuration scheme you described is overall feasible.

Your plan is to configure two DHCP servers (192.168.1.13 and 192.168.1.14) as DHCP clusters, which can improve redundancy and availability. Using the virtual IP (VIP) address 192.168.1.15 instead of the original single DHCP server address is a secure solution, so that clients only need to configure the IP address of one DHCP server. When one DHCP server is unavailable, the other can continue to provide services.

You mentioned that the DHCP cluster will use the same DHCP range (192.168.12100-200). Ensure that the two DHCP servers do not allocate the same IP address repeatedly during configuration. It is recommended to allocate IP ranges appropriately based on the load capacity of the DHCP server, such as one server responsible for 192.168.12.100-150 and another server responsible for 192.168.12.151-200. This can avoid IP conflicts.

You plan to change the IP helper address of the Cisco router to 192.168.1.15, which is appropriate. In this way, all DHCP requests will be forwarded to virtual IP addresses for processing by DHCP servers in the cluster.

It is reasonable to set DHCP Option 43 to binary (192.168.1.57) pointing to the IP address of the wireless controller. This setting is typically used in Cisco wireless network environments to enable wireless devices to obtain controller information. Since this is a parameter that points to a specific device and is not related to the high availability settings of the DHCP server, you can keep it unchanged after switching to the DHCP cluster.

When making such changes, please ensure that you make a backup before implementation so that it can be restored in case of any issues.

Overall, your plan is reasonable, just pay attention to the allocation and management of IP addresses to ensure the continuity and reliability of DHCP services.

I hope the information above is helpful.

If you have any questions or concerns, please feel free to let us know.



Regards,

Jill Zhou

Answer 2

Hi Jill,

thanks for your reply and as you mention that keep dhcp unchanged on the settings, I only need to install the cluster feature on both servers and I think I need to unauthorised the dhcp setting on both server, and once cluster installed I can start re-configure the dhcp settings and the previous setting will be gone such as option 43 ? Please correct me if I’m wrong, Thanks

Answer 3

Thanks for your reply.

First, you mentioned that you need to install the clustering feature on both servers. This is a necessary step in order to consolidate the two DHCP servers into a single high-availability cluster, improving the redundancy and reliability of the service. Once the clustering feature is installed, you do need to decommission your current DHCP settings so that you can reconfigure them in the new clustered environment. This is done to ensure that the new configuration is in effect and is no longer affected by the original configuration.

Next, with regard to the reconfiguration of DHCP settings after installing the cluster, including DHCP Option 43, you mentioned. It is important to note that if you do not keep the original settings when reconfiguring, especially the specific options and addresses, you may lose the original configuration. It is recommended that you export or back up your current DHCP settings (including all options, such as Option 43) before installing the cluster. This will help you readjust your settings after the installation is complete to ensure that functionality is not lost.

Again, during reconfiguration, make sure you double-check each configuration item to accommodate the new cluster setup. The DHCP servers in the new cluster share the load, so consistency is needed in the allocation of IP address ranges and the configuration of options. This way, you can ensure that the user's device gets the IP address and its associated settings correctly.

At the same time, in the cluster, you should be able to keep the DHCP option, such as Option 43. While you mentioned that the configuration may be "wiped out", in reality, the installation of the clustering feature is separate from the existing DHCP setup management, and you only need to reconfigure it as needed after the installation is complete. Make sure that you don't need to remove all the options when you install the cluster, and you may just need to adjust the IP address allocation range, etc.

If you have any questions or need further assistance, please feel free to ask.