Device Instrumentation

Not all devices are created equal.

I know this seems like a piece of Captn’ Obvious wisdom, but it bears thinking about a little in context of network management.

One of the things which I see all the time is someone asking to do XYZ on the device. Whether that’s pull serial numbers from power supplies, or read the sticker on the back of a switch. There are some things that are just outside the realm of possibility, or would just be to difficult to put into place.

If you are seriously looking at implementing an NMS, you need to get friendly with SNMP. Simple Network Management Protocol is probably the most common management protocol on the planet.

To be honest, SNMP is a second language and I would highly recommend anyone who wants to get SERIOUS about network management pick up a book or two and start learning it.  SimpleWeb has some tutorials, podcasts, and slide decks that they make available which may be a good place to start. 

In a nutshell, SNMP MIBs fall into two major categories

Public – These are the standard MIBs that are defined by the IETF. These are your friends, the bridge MIB, dot3 MIB, Entity MIB, etc..  MOST vendors should support these.

Private – Also referred to as Enterprise, these are the MIBs which Vendors write to support their own device specific functionality.

Occasionally, someone brings in a non-snmp capable device and asks for it to be monitored. And then they complain because you can’t make the same pretty graphs.

If it’s not instrumented in the device, we can’t do anything with it.

Let me say that again…

If it’s not instrumented in the device, we can’t do anything with it.

Here’s an example: Say someone comes to you and says ” Hey! Can you please tell me what the serial number is on the power supply in XYZ vendors chassis switch?”

I check the MIBs and it seems that XYZ vendor hasn’t instrumented serial numbers as one of the piece of information which they make available. So the answer is ” No, I can’t”

Then they complain that this NMS stuff, or the specific NMS product sucks. Remember

If it’s not instrumented in the device, we can’t do anything with it.