I’ve decided to take on the CCNP certification, so I’m going to wind up with a few posts will be more my own notes than anything. 🙂 A switch port on a 2960 comes up with a default configuration on VLAN 1. What happens from the perspective of spanning-tree? First, the port comes up on […]
Aaron's Worthless Words
It's possible that someone somewhere needs to know this.
I’ve got a non-technical one for you today. If you’re paying attention to stuff around you, you’ll probably end up with a little paranoia after reading this. We’re having another circuit installed, and the LEC came out to do their end-to-end testing. The tech, Dan, calls me up on the phone and tells me who […]
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 […]
This is a great one that I have to share. A couple of coworkers walk in today and ask for some help on an issue. It seems that a business unit was having latency problems with a web app, and, after research by the product team and sysadmins, nothing wrong could be found. Lots of […]
Have you even noticed that your new servers all have 2 NICs on the board? At least all of them that I’ve seen in the last 3 years have. A lot of server admin actually use them in a NIC teaming scenario where both NICs are used as one logical device — much the same […]
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 […]
We discussed SPANs earlier, but let’s talk about RSPANs for a bit. Can anyone guess what the “R” means? You guessed it — “Remote”. An RSPAN is a way to get traffic from a SPAN source on one switch to a SPAN destination on another switch that’s connected via a trunk. The basic premise is […]
I can’t believe I haven’t blogged on this yet. SPANs are one of my favorite things in the world. The switched port analyzer (SPAN) is a mechanism on Cisco switches that allows you to take traffic on one port and copy it to another. It’s generally used to get traffic to a sniffer or IDS […]
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 […]