If the servers are in two separate locations, like two datacenters on either side of the country, you are stuck with DNS-based load balancing. Like others have mentioned, Cisco, F5 and others have products which will handle this for you and take into account some other factors when directing traffic. DNS load balancing works quite well, I've used the F5 BigIP and 3dns extensively, and the Foundry ServerIron (which is fairly cheap). A little more detail into what you are trying to do would help. The most common setup with this is to have multiple datacenters, and each datacenter has a cluster of identical servers behind something like a BigIP. The traffic is load balanced at that level, but your Global load balancer which hands out DNS communicates with the local guy to figure out what the current traffic ratio is and modifys its dns replys accordingly. There used to be a free one for linux called Eddie, which looked quite robust. I think it was eddieware.org or eddieware.com. There is also the linux virtual server project, but I don't believe it has support for Global load balancing, only local. As a side note, I've used Cisco's CSS, F5's stuff, Alteon, and Foundry. Out of all of them that I've used, the Foundry had the least problems and had a nicely structured config. I would recommend the CSS, but it seems to have quite a few bugs in the code that still need to be worked out, but the support for SSL acceleration is nice. F5... I used to really like F5. In fact, I was one of their beta sites back in 1999 and 2000. After some problems with code that "broke" things, we discontinued the beta program with them. Shortly after, their new releases were getting worse and worse, their support seemed unwilling to help (for almost $100k a year in support, you'd think they would care), so I switched to Foundry. An insider over at F5 told me that most of the people who had written the original code back in 1999/2000 were all gone, and most of the problems were a result of the new people not yet wrapping their heads around the code. This was about 2 years ago, so it's possible they've figured out how everything is put together and it's better now. For awhile though, it was quite bad. Feature-wise, F5 has more features than any of the other ones, Cisco CSS comes in a somewhat distant second place. For most people, any of the above will suffice and most of the features available in F5 and Cisco are just nice-to-have's and not a requirement. -jay

-----Original Message----- From: Gerald [mailto:gcoon@inch.com] Sent: Wednesday, August 06, 2003 1:12 PM To: Jason Greenberg Cc: nanog@merit.edu Subject: Re: Server Redundancy

On Wed, 6 Aug 2003, Jason Greenberg wrote:

...

Can I have some suggestions on how to load balance servers

that are on

...

seperate IP blocks? Is there any way to perform translation at this level? Exclude DNS based balancing please...

vrrp on FreeBSD is supposed to be a free solution to allow machines to watch each other and take over IP addressing if connectivity is lost. Depending on how remote your IP blocks are and how much control you have over the routing equipment in between, your only choice may be a commercial solution.

http://www.bsdshell.net/hut_vrrpimpl.html

I've not used it, and the documentation is currently in French.

The HUT project also has FreeBSD load balancing software for free that is supposed to function like F5/Alteon/Cisco LB.

I've maintained the Cisco CS 1100 (when it was Arrowpoint) in production. You could VLAN remote machines into what you want to do on that. I think that equipment has changed quite a bit though since Cisco bought them and my experience is over a year old.

G