I've been searching the forums but so far can't seem to find mention of what I'm looking for, although I thought we've had discussions like this before.
I currently run Cacti and Solarwinds for all my networks.
We have several fiber networks that are basically private WAN's. We then setup site-to-site VPN with the clients to allow us to monitor and configure our equipment as needed. Many of these networks are built with redundant connections that due to contractual reasons are not always plugged in. This causes extra management of the monitoring systems if no one catches this.
I'm trying to find a free system that can monitor these networks. I want something that can support SNMP and will automatically map the network via the information given to it such as management network, SNMP, etc. or on it's own via CDP. That being said all networks are Cisco. Any ideas for something that can gather it's information automatically and show a network map with bandwidth utilization? I thought I heard MRTG or Nagios could do this but I'm not coming up with anything on my searches.