High Availability for TCP socket using device

Hello,

We have a custom application gateway that listens on a none standard port for incoming connections on the internet (it's not a webserver). We have two instances of this application running on separate servers and are interested in ways to create automatic fail-over to the second box if the first box is not longer available.

I believe that a content switch or load balancer device is probably what we're after but I'd like to know from anyone who's had experience with these. Here are a few questions:

- It appears that most devices are geared for web servers, are there any restrictions to web traffic for these devices?

- Do all the devices support an active/passive setup rather than a distributed load setup?

- Do the devices have any management software that lets you gracefully fail-over to a different box (not dropping existing connections)

- Are there any options that we might have overlooked (such as software) to perform this function?

Thanks in advance if you've got any time to help!

-Joel Duckworth

The answer to all the questions are below.

No, you can configure them to use any port your want.

I have never heard of anyone using them in an active/passive way, why would you want to or need to? If you need clients to always connect to the same specific real server that can be configured on the content-switch (it's called "stickyness"). If you need to reconfigure something in order to failover, you don't need a content switch. If your primary server is "bigger" than your failover server, you can configure the content switch to favor the "bigger" server.

Yes

IOS Server Load Balancing (SLB) is supported on 6500/7600's (Sup2, Sup2a and Sup720), 7200's and 7300's. It will do everything you have described. We use IOS SLB extensively, and found it to be one of the most reliable features in IOS. In the 7 years we have been using IOS SLB, we have not experience a single is issue with it.

If you don't have these types of devices, you should check out the Citrix's Netscaler. They're about a 50% of the cost of the Cisco ACE, and has more features, (its even less expensive than the Cisco CSS.) Whatever you do, don't even consider the CSS, it is a dead end platform and the only major feature it has that you can't do with IOS SLB is SSL offload. If you need SSL offload, the Netscaler will do that for less money, plus all the same features as the ACE.