The 2920 series switches from HPE/Aruba has a special feature that no other switches in the old ProCurve/E-Series line-up has; dedicated stacking interfaces. On other HPE switches, stacking merely facilitates “simplified” management, by allowing you to manage any switch in the stack from the stack commander’s CLI. On the 2920 series however, you can use dedicated stacking interfacing, giving you 2 20 Gbps links to other switches in the stack and merging two to four switches into one coherent switch. This is quite similar on how stacking works on some Cisco models, but the specialized stacking interfaces gives you higher speeds between the members. In this article, I’ll show you have to set up the commander switch and how to add switches to the stack once it’s created. I’ll also go into how it affects the configuration of the switches, which is quite crucial if you want to stack switches that are already in production.
When configuring network hardware over the network itself it’s very easy to issue a command that breaks the network connection to the switch, requiring you to visit the switch and connect to it with a console cable to fix the issue. This is not a big problem if the switch is just down the hall in a closet somewhere, but in today’s world a switch that you’re configuring might be hundred of miles away from where you’re sitting.
Of course this whole issue can be sidestepped by just thinking through what you’re doing before hitting the enter key, but in the real world this is not always an available luxury.
The solution to this problem is to cleverly utilize the “reload” command in combination with the “write” command.
Last week I updated the core switches at one of our sites to two new fancy HP 5406zl. Along with all the nice new features that came with these two beasts was PoE on all ports. All was good and well, until today, when the logs on one of the switches started filling up with 3 errors about PoE delivery on a specific port.
After a lot of cable-tugging and google, it turned out that a subcontractor had installed a small V1810-8G switch in the network. And among other things, these small buggers can be fed by PoE on Port 1. But since it was hooked up with a wall-wart, that collided with the PoE-feed. One would think that HP could put in a bit of error checking on the PoE side so that a device that already have a functioning power supply does not request a PoE-feed.
So, if you’re struggling with a log full of PoE errors (I got 110 000 events in half a week), do a quick google if the connected device supports PoE.