Tag: cisco

Cisco stuff

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…

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…

We ran into this today, and, though I knew it existed, I never actually saw it in the wild.  I’m talking about MAC access-lists. In the example setup, we have a DMZ off of a firewall that contains a whole mess of servers — email,…

I got my CCNP certification library the other day to finally get myself another cert, so I’ve been doing some reading of late. The thing I hate about certs is that, even if you have all the experience in the world, there’s always a whole…

We all have limited budgets these days. Long gone are the days of unlimited resources and uncontrollable expansion of the network, so it’s important that any network dude or dudette pay attention to the open-source world. Below is a list of stuff I use at…

I assume you take every word I say to heart and that you’ve been using Dynamips/Dynagen for a few days now, right? Good. That’s a start, but let’s break down a simple lab to make sure everyone’s on the same page. I run my labs…

I’ve run across articles for these apps a thousand times, so I thought I’d get in on the action. Dynamips and dynagen are a pair of apps that make simulating Cisco routers very easy. I use them constantly at the office (and even at home…

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…

We’ve done some tracking with HSRP in other articles, but there are lots and lots of ways to use object tracking on an HSRP device. In our example network, we tracked the interface, and, if it went down, we decremented the standby priority. What if…

I like [tag]layer-3[/tag] [tag]switch[/tag]es. They give some great flexibility and bang-for-the buck, but most people overlook one issue with these things that can cause security problems. Most people configure the [tag]VLAN[/tag]s, put an IP on the VLAN interfaces, and put it in production, but the…