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BlueWolf's Howl

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December 20, 2007

Little Update

Already today I used some of the things I read in the Visio book. I was called on to troubleshoot a problem with an HP chassis - which had a number of very confusing and intricate connections. As part of the troubleshooting, I realized that a picture would benefit the discussion. Very quickly I popped off a diagram. Of course it was more of a conceptual diagram than a technical one - and used rectangles to represent the chassis and also the switch to which it was connected. I used callouts to group the IP addresses and the pointer of the callout to point to the connection where the addresses were found.

It eliminated a lot of confusion very quickly. Server people think in server terms. However, no matter where the IP address is or isn't located on the virtual server chassis -- I can tell for sure which port is seeing that IP address. If I have 12 addresses and I'm seeing those all on one port, yet I'm seeing traffic on 6 ports - something's wrong. Yeah, those are the ONLY IP addresses configured for that network. Uh huh. So what magic traffic is travelling on those ports that do not have an IP address? Even if the chassis is load balancing on its own, if only ILO traffic is going to the ILO ports, then what traffic (and IP) is going to the other 4 ports? And it's going in both directions...

Oh...yeah.... I forgot. Yeah. Just as magically as the traffic flowed, someone magically remembered that about a month ago (when the problem started), he configured two servers to back up on that network. Oh yeah - here's two IP addresses on that subnet that I forgot about. Uh huh.

It makes quite a few lightbulbs go off in people's heads when they're looking at a diagram and seeing connections that they don't have an answer for...

"Well, nothing's supposed to be on that network." Fine. However, there IS traffic on that network. In both directions. How does that happen when you supposedly haven't configured anything for it? Suddenly there's a nagging suspicion that perhaps there's something missing ~

A picture is worth a thousand words.

Posted by BlueWolf on December 20, 2007 09:13 PM