Bandwidth Monitoring and …

Posted on July 17, 2007 3 Comments

When it comes to network management, I’ve always been more of a “let’s buy some switches and pull some cable” kind of guy. Actually managing, extending and supporting an existing network was never all that interesting to me.

Now that it’s party of my job, however, I suddenly care a lot more than I used to!

Our office has a pair of T1s (bonded to 3Mbps) for data and phones. I also added a business class DSL line a few months back when things seemed to be sluggish. Granted, I couldn’t quantify that the network was slow, but adding the DSL line to the mix seemed to help.

Side Note: I could add that add’l DSL link because my primary firewall has multiple WAN interfaces and supports percentage based bridging or load balancing. Rather slick, really.

As the business grows, there’s been a lot of talk about more VPNs to 3rd parties such as large customers and new partners. Some of the discussions regarding the potential activity over those VPNs concerned me enough to realize I was going to have to finally do some digging for a good bandwidth monitoring tool. I need to know where I’m at before freaking out and buying more data lines. Thus, I better get a baseline down before I bring up all these new links.

My research didn’t take long. I found ntop almost immediately. Looked like just the ticket so this morning I brought my trusty old P2 laptop to work (as you may recall, I couldn’t get Ubuntu running on my more modern one last night).

I already have a new firewall/vpn endpoint in place for these “external” client connections to use, and one link already up, so I figured that would be my baseline. Grabbed an old 4 port hub and put it in between the T1 router and the firewall and ran a cable over to my laptop and fired up ntop.

Confession time: After running ntop from the command line^[1] I just sat and stared at the console, wondering if was going to actually do something. *blush* A quick glance back at the website helped me realize that I’d have better luck connecting to its web interface (http://localhost:3000).

Ah ha! Pictures! Data! Graphs! I’d show screen-shots but I forgot to take some… Suffice it to say, this seems exactly what I’m after — especially the network load area.

The display refreshes periodically and shows some great stuff, including current, last 5 minutes, peak and average bandwidth usage.

Problem solved. My needs are simple and this more than meets them. To monitor various segments of the lan, or external interfaces, I just need to pop my little hub into the middle and start up another run of ntop.

I look forward to learning more about the features and capabilities.

Oh, while writing this article I also tripped over NTop-XTRA which, among other things, runs on windows… might add that to my toolkit.

On to the next challenge.

(to be continued)

[1] sudo ntop -b -z if I recall correctly.

Tags: monitoring, network, ntop, open-source, operations