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 […]
My home network has a Linux box running IPTables as it’s center point, and, since there are four networks, it has 4 NICs and 4 cables into the switch. I kept running into problems with the NICs (they would reorder depending on what flavor of Linux was installed), so I wanted to consolidate the NICs […]
Earl Zmijewski of Renesys has an analysis of the SuproNet incident that took down a good bit of the Internet on Monday. From the blog: This single Czech provider announcing a single prefix caused a huge increase in the global rate of updates, peaking at 107,780 updates per-second. This peak occurred at 16:30:54 UTC, less […]
I’m kind of an obsessive-compulsive when it comes to numbers (1, 2, 3, 4, 5…), so I’m fairly excited about next Friday (..6, 7, 8, 9, 10…) when Epoch time reaches 1234567890 at 18:31:30 on 13 February(…11, 12, 13, 14, 15…). I’m sure my ADD will kick in (Oh, look. A squirrel!) right before, but […]