The Research And Implementation Of High-Availability DHCP Service With Load-Balance

Because of the convenience of managing IP addresses and dynamic allocating IP addresses to clients which want to link in the Internet, DHCP service becomes the basic service and is popular in network architecture,. To avoid the single point of failure of DHCP servers casing the DHCP service not available, we must increase DHCP servers’ redundancy to improve the availability of DHCP services. In academia and industry, the research of how to improve the availability of DHCP services has a lot.In academia, IETF proposed the DHCP FAILOVER draft which defined the interaction and hot backup solutions of DHCP servers. This draft regulated the communication between servers and servers’ action.This paper not only briefly describes the DHCP protocol, and the details of improving the availability of DHCP services through hot backup and fail over, but also describes the status of DHCPFAILOVER draft and shortcomings because of which it didn’t become a IETF standard. In the industry, all vendors designed their own high-availability DHCP solutions according to the specific network deployment. This paper summarizes and analyses these different solutions, and points out the advantages and disadvantages of each solution and scenarios. This makes some contribution for the study of high-availability DHCP services.According to the research of DHCP FAILOVER draft and the analysis of several vendors’ solutions, this paper proposes the HWM-DHCP solution which is based on high water mark. This solution can improve the utilization of IP address, improve the stability of DHCP servers, improve disaster recovery capabilities of DHCP service, and in the end improve the availability of the DHCP service. There are two components in HWM-DHCP solution, HWM algorithm in DHCP server and load-balance algorithm in DHCP Relay agent. HWM algorithm is divided into two parts, the allocation algorithm of IP address pool between servers and the allocation algorithm of IP address. In this paper, HWM-DHCP solution will be describe in detail, and the demo of this solution will be developed in LINUX. In the end, this paper introduces the assessments and conclusions of the HWM-DHCP solution, by comparing it with other solutions and testing the demo of the solution.