Setting up Spanning Tree on HP switches is really easy, after you’ve done it a couple of times, but getting it configured can seem like a daunting task for beginners, espcially in a production network. Here are some simple steps on how to get it up and running in no time. Note that enabling STP might cause small network outages, so don’t do this in a production network if you haven’t tried it before! All commands are written within “citation”-marks, so that’s what you need to enter into the CLI on your switch. For completeness I’ve added all the commands in order at the bottom of the post, which might be handy if you’re just looking for a CLI-reference.
The first thing to do is to select your root bridge (the central most switch in your network). Enter CLI and type “configure” to enter config mode. Then enter “spanning-tree” to enable it. That’s all you need to do on a switch to get STP up and running.
Next we need to set up root bridge priority on your core switch(s). When the switches in your network selects their root bridge, they look at two things, the switch’s MAC-address, and a thing called STP priority. From the factory all switches have the same priority (step 8 of the 16 configurable steps) so the switch with the lowest MAC automatically get’s selected as root. THIS IS NOT A GOOD THING, as this will basically make your whole network look for the shortest path to a random switch in the network, which is usually a rouge switch installed by a non-IT employee under someone’s desk, at least with my luck. What we want is for them to find the shortest path to the core switch, so we will alter the priority.
This is easy to do as well. In the same config mode that you just enabled STP in, type “spanning-tree priority 0”. This sets the root bridge permanently so that it won’t ever change without you wanting it to. If you have 2 core switches, set the other one to priority 1 so that if the main core fails the whole network will switch to the other one.
Run “write memory” to save your changes and log out.
Run “spanning-tree” in the config mode on all your other switches. That’s all! Remember to run “write memory” to save your changes!
This is only a short intro into STP, but it’s sufficient for beginners to get started, and after you have this down you can then easily start to add the more exotic features.
Here’s the full CLI for those who want it;
Configuring the root Bridge:
Procurve 4204vl-1# configure Procurve 4204vl-1(config)# spanning-tree Procurve 4204vl-1(config)# spanning-tree priority 0 Procurve 4204vl-1(config)# write memory
Configuring the fail-over root Bridge:
Procurve 4204vl-2# configure Procurve 4204vl-2(config)# spanning-tree Procurve 4204vl-2(config)# spanning-tree priority 1 Procurve 4204vl-2(config)# write memory
Configuring the other switches:
Procurve 4204vl-3# configure Procurve 4204vl-3(config)# spanning-tree Procurve 4204vl-3(config)# write memory
This post is part of a new series called Network Friday, where I explain a new networking concept every Friday and tell you have to configure it on (mostly) HP hardware. The series will mostly focus on the configuration side, as I feel there are lots of resources out there that do a fine job of explaining complex concepts, but very few that show you how to do it on your specific hardware. This series aims to address this somewhat, at least on the HP side of the fence.
This how-to was originally posted over at the Spiceworks community: