Eric Stewart: Running Off At The Mouth

So yes – spending a lot of time with the new load balancers and finding out all sorts of things about their operation I didn’t know about, that (at least in this case) were fairly easy to fix.

The thing is carrying actual, important, production traffic now.  Most if it is short lived web-based stuff; short enough that the transfer completes well before a failed session establishment on the firewall is noticed.  But someone was noticing, and it took me doing many packet captures to figure out exactly what was going wrong (and realize it was actually my fault).

One of my worst weaknesses as a network admin is that (mostly due to a weird conflux of laziness and time restrictions) I tend to not read up on a topic as much as I should before I implement; or at the very least, I don’t retain what I do read and put certain settings in without considering that there might be serious ramifications. Such is the case with vPC; I don’t know it as well as I should, and I trust it even less, but it’s being used in our data center (DC) networks heavily. So it was that during the load balancer migration I’m in the middle of, I came across a case where vPC made a packet capture lie.

It’s been a while since I’ve posted. If I’m not busy at work, I’m avoiding anything related to work. One issue I’ve been working on for a long time has involved a load balancer migration from one vendor to another. I ran into an issue which was brought about by the new vendor claiming our configuration was supported … only to find later on that it was not. This is not wholly their fault – we’ve been doing load balancing in possibly an unusual way for quite some time. Read on for the hows and they whys, and why you occasionally have to watch out for Ethernet doing exactly what Ethernet does.

Just a quickie, probably subject to some editing later on, about how to use the “bind” option multiple times with a given service – mainly, to have a TFTP server operate from behind a virtual IP as the virtual IP (instead of becoming its real IP in the middle of the transfer).