How to enable SNMP on a 3com to work with Cacti ?

April 21, 2008 7:48 AM

SNMP on a 3com 4500/5500 and Cacti setup help ??

I have a 3com 4500 and recently installed Cacti 0.87b on a windows xpsp2 box. I never configured SNMP on a 3com before, anyone have prior experience ? I was getting data on a graph previously, but for some reason i'm not getting any data on the Caci graph.

Take a look at this screen shot

And this from the 3com SNMP statistics.

I have NET-SNMP installed, but not sure what would be the right syntax for snmpwalk to determine if everything is setup alright.

posted by hboogz to Technology (6 answers total)

My experience with rrdtool/cacti and SNMP was that whenever there was a problem with graphing, I was either not hitting the correct MIB-entry, or my 'type' was off (gauge vs. counter, and so on). A good way to learn the ins and outs of cacti is to start with plain-vanilla rrdtool - the tutorials are great.

The syntax for snmpwalk is pretty simple, assuming you're using snmp v1:

snmpwalk -v 1 (hostname or IP) (community string)

ie:

snmpwalk -v 1 10.1.1.1 public

...which should yield the entire MIB and each entry's current values. Picking through these can be dicey, which is why it's enormously useful to get a copy of the MIB document from the vendor if at all possible. You can usually find these things buried in their document repositories. IIRC, cacti does a pretty good job of choosing the correct items to monitor for servers, routers, switches and such.
posted by jquinby at 8:50 AM on April 21, 2008

Ah, and in digging around, I found your post on the cacti forum. One way to see if the is data getting into the RRD databases is to use the rrddump command to output the contents of the DB. If you're logging to MySQL or something else instead, you should be able to grab from there as well.
posted by jquinby at 8:55 AM on April 21, 2008

Response by poster: jquinby,

Thanks for the update.

I ran the command snmpwalk -v 1 -c %community% IP Address and the MIB list populated with TONS of data. I am not sure how to determine if i'm hitting the right MIB-entry or to even know if the Type is off ?

I know i need to look at my vendors MIB documention and compare that to what CACTI uses, but what and where exactly am i doing this ?

I'm really a newbie when it comes to SNMP.

I'm using mysql installed on my local machine.

The rrdtool dump feature seems like a tool i would use to transfer rrd file ? what syntax do i run now to help me troubleshoot my problem?
posted by hboogz at 9:15 AM on April 21, 2008

Best answer: The MIB docs alone will tell you about the entries and their respective data types. Sometimes they're sort of self-evident - entries for a Linux host might contain, among other things, the contents of the routing table, disk partition information, and so on. Even then, having the actual MIB file on the machine means that each entry will get its proper name, rather than ".1.3.1.1.4.5.1...n" and so on.

If you're logging the data to MySQL, you can log in to the database and do some simple SELECTs to see if there's any data in there. The rrddump tool is used to display the contents of the round-robin-databases used by rrdtool for storing data. You're using MySQL, so you can skip it.

SNMP is a fairly simple protocol - it only contains 3 commands: GET, GET-NEXT and SET. The complexity comes in deciphering the vendor-specific MIB tables. Even then, they're going to be written in ASN, so they need a bit of scrutiny to be useful.there, too.

The MIBs for the 4500 are here (about halfway down)- download the bundle and pick through them manually or using a MIB browser, which will let you view them graphically. You should be able to find the entries for the items you want to monitor - grab those strings and plug them into cacti manually.
posted by jquinby at 9:31 AM on April 21, 2008

Response by poster: jquinby, so far you've been a tremendous help, thanks a mil.

I will get started on that, most definitely. One quick question before i start, how i enter the MIB entries manually in cacti ?
posted by hboogz at 9:40 AM on April 21, 2008

It's been a while since I've looked at the cacti UI, so I'm afraid I can't guide you right to it. This thread in the cacti forums talks about entering custom OIDs into a generic template.
posted by jquinby at 1:38 PM on April 21, 2008