Eric Stewart: Running Off At The Mouth

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.

In which I regale you with a tale involving the salacious behavior of the Catalyst 6500 when compared to the more chaste Nexus 7K line.

A revisit to an earlier post and why what I outlined there was a bad idea. Using Bank Chaining, while allowing you to use more banks for ACLs, has its penalties …

I get an error message while pasting in some VLAN interfaces:

ERROR: Module 1, 2, 10 returned status: Tcam will be over used, please enable bank chaining and/or turn off atomic update.If bank-chaining is enabled on other modules and this is a new linecard insertion,please enable bank-chaining prior to reloading this module.

Well, this (I think) is what it means, and how I resolved the situation.

Having been silent about my Cisco Nexus 7700 work for a while, I come across something that irked me a little bit while trying to configure our 7700 pair to replace the 6500s, involving Virtual Port Channels. So here’s what Virtual Port Channels are and how they basically work, as well as one or two things that you might want to be aware of. So, this may end up getting quite long …

It is possible on the Nexus 7700 line, with certain optics, to break out 40Gb (and eventually 100Gb) to 4x10Gb interfaces (no one knows for sure what 100Gb will do – it will either be 8x10Gb or 10x10Gb). In this post I go over how $JOB is doing it (at least with the 40Gb) and what you need to be aware of. I do touch a little bit on the 100Gb breakout future and explain why we were looking to do it.

We racked our Nexus 7710 recently. Here’s some of the things you might need to know regarding getting this monster of a chassis into a rack.

So we powered on our first to arrive Nexus 7706s (two of them). Here’s some notes so far.