Date: Tue, 23 Mar 1999 15:03:39 -0800 From: Mike Thompson <miket@dnai.com> To: freebsd-net@freebsd.org Subject: IP alias configuration for high availability Message-ID: <4.1.19990323134009.0099fe10@mail.dnai.com>
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Hello everyone, I'm looking for comments on the following proposed scheme for managing IP addresses between various servers for high availability. I am attempting to come up with network configuration where our web servers running FreeBSD 2.2.8 will respond to two different IP addresses on the same network interface. The idea is that first network address for a server would be fixed on the reserved IP addresses of 192.168.xxx.xxx (behind a router to prevent packet leakage onto the Internet). These fixed addresses would be used for private communication between the various servers. The other addresses used by each server would be from the Internet IP address block assigned from our ISP (example 209.185.152.1 thru 209.185.152.20). The Internet IP addresses would be round-robin load balanced from our DNS server. Under centralized control any server could be commanded to alias an IP address from this block. With such a configuration we hope to be able to hot swap servers among the various Internet IP addresses for system maintenance and emergency situations for high availability. To configure the fixed and dynamic addresses for a server I can use the following commands: ifconfig ed0 inet 192.168.0.1 netmask 255.255.255.0 ifconfig ed0 inet 209.185.152.1 netmask 255.255.255.0 alias To dynamically add another Internet IP address to the server I can then issue the command: ifconfig ed0 inet 209.185.152.2 netmask 255.255.255.0 alias To dynamically remove the IP address to the server I can issue the command: ifconfig ed0 inet 209.185.152.2 delete From my testing it seems everything works pretty well. I have found that I need to manually break the association between an IP address and ethernet address on the servers by using the "arp" utility. Are there other issues that I should be aware of by following such a strategy? Thanks, Mike Thompson To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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