On the CSM, you can configure a vserver to use a main and backup serverfarm which is used if a serverfarm is toast.  If all the RIPs in the main farm are out-of-service, the CSM will start to treat the backup farm just as if it’s configured to be the main one.  Once one or more of the main farm RIPs have recovered, the CSM reverts back and uses those again.  “Give me an example when I’d use it!,” you say?  Since the CSM is made for HTTP connections, we’ll assume that you are using it for such.

The CSM is pretty bad little box.  It not only watches layer 4 items like TCP connections, but also talks HTTP, which you can use to do some custom, or policy-based, load balancing.

Policies are the objects that make custom balancing work.  Like everything else (it seems) on the CSM, a policy is an object made up of other objects – maps and serverfarms.  A map matches patterns based on a number of things including the URL and HTTP header values, while the serverfarm directive tells where to send traffic that matches the map.  If, for example, you want to send all requests with “/admin” in the URL to a management server instead of the regular web servers, you can do it with a policy.

My buddy told me that my site is the only place on the web with documentation on the Cisco Content Switching Module (CSM). I also noticed a few months ago that every TAC case I’ve opened on the CSM has been handled by the same guy. I seriously think that the only people in the world that really know about these things are me and him. Cool. I better get some more content up.

I had an article a few weeks ago about the Cisco CSM, which is a load-balancer module for the 6500 series switches. This thing is a pretty good device, but monitoring the connections to each VIP and RIP is not very straightforward. If you have an SNMP monitoring system like Cacti or MRTG, you need to know the OID to monitor, but it doesn’t work like anything else in the world.

Cisco’s Content Switching Module (CSM) is an application accelerator. Or is it an application networking service module? I hate those fancy buzzwords – it’s a load balancer. It’s a module for the 6500 series switches that lets you load balance services in any VLAN and can also be set up for high-availability. I could go on for a while about the features, but let’s keep it simple for now. A short tutorial, if you will.