Need free or cheap network discovery tool and information about vlan's/trunking/tagging ports

J C used Ask the Experts™
I started working for a university this past week. This is only the second enterprise level network I have worked with and they are several years apart. I want to get up to speed on vlan's and trunking...tagging and untagging. I need a real understanding of this as there are thousands of VLAN's in use on the network. I also am looking for a discovery tool that can search across the network and identify our switches/routers and servers. The documentation is very poor and I want to get a grasp on this ASAP. Any feedback is appreciated!
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Hi there,

There are a few good free tools available here:

Give that a go and see if that suits your requirements.
Marius GunnerudSenior Systems Engineer
Top Expert 2013

here are a couple of generic sites you can look at for trunking and vlans.

Wireshark is another good network monitoring tool.  Also I know Cisco has built in tools and commands you can use. If you have other hardware then I am sure they also have commands or tools you can use to do the same.


There are plenty of tools for scanning networks, identifying VLAN's can be ab it trickier.  For VLAN's, you best bet is to locate the VLAN/spanning tree root of the network and start mapping out the VLAN's you see from there.
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As far as the switching goes....

A very, very good tool we use here at our University is "Netdisco". It will go out and find every switch on your network, list them by model, tell you what VLAN's are in use and even give you a map of your topology. The bad part is you have to have some unix knowledge as you have to install on that platform. There are install scripts that help alot for CentOS.



Will it install on top of the Ubuntu linux distribution?
I have it installed on CentOS but it will install on Ubuntu, my original install was on Ubuntu but I had a server issue and when I resinstalled I wanted to try a different version since I had such a hard time getting it working. Your first time going around, please take my advice and install on CentOS and use the install script found will make your life easier. Now if your a Linux expert, then disregard :-)

Here is the webpage to install manually. Join up for the mailing list, you can ask questions and get great support. I lived off the thing during my initial setup. Hope this helps.

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