A coworker wanted to move servers from one tier to another. There’s a really simple solution that you may not see since policy is in the way.
It seems that we have another piece of evidence that Cisco doesn’t like the CSM. From what I’m able to creatively interpret, the software developers didn’t think anyone would be running the CSM for very long, so they set a variable that expires CSM-inserted cookies at 01:01:50GMT on 1 January 20101. If you’re using cookies […]
SSH is more than just a shell. You can copy files from and to a server or piece of network gear with it. You can use it to tunnel traffic. Possibly my favorite, though, is to use SSH to run a command on a remote box without interacting with a shell. One of my biggest […]
We talked about running multiple data centers on a stick back in August, which is where you have multiple logical pairs of client and server VLANs on a single CSM for different tiers or functions. The big point of the article was that you had to do some fancy forwarding to get a server-initiated connection […]
I must be bored since I’m posting again. A colleague asked me to change the failed value of a TCP probe today. It was no big deal, but, when I looked to see the status of the change, I noticed interesting stati of the RIPs. switch#sh mod csm 7 probe name TCP80-PROBE detail probe type […]
I’ve talked about probes and stuff on the CSM, but I never mentioned what happens to the connections to a server that fails. That is, if I’m connected to server A in a cluster and that server suddenly commits ritual seppuku, what happens to my connection through the CSM? Remember how the CSM works? You […]
Did you catch the article on setting up fault tolerance on the CSM? In that article, I mentioned that Cisco recommends a dedicated trunk for the FT VLAN if you have two HA CSMs in two chassis. Discuss amongst yourselves while I drone on. Why should you set up a dedicated trunk for this stuff? […]
There are three different ways that a CSM checks for the health of the servers — active probes, inband health checking, and inband HTTP monitoring. Let’s talk about active probes. Active probes (or just probes) typically send traffic to one of the RIPs of a serverfarm, do some stuff, and give a pass or fail […]
Like (nearly) everything in the Cisco world, you can set up your CSM to fail over to another module when the primary dies a horrible death. You can have two in the same chassis or even have them in separate chassis — the process is the same no matter how you have it set up. […]
That’s an awesome title, eh? I’ve mentioned a router-on-a-stick before but not a data-center-on-a-stick (DCOAS). This is one of those Cisco terms I ran across a while ago and is a group of servers sort of sticking out on their own behind a load balancer and/or firewall. Connections to and from the server group go […]