NeDi is a low noise network discovery, management, and inventory system for network devices with a user friendly Web interface. It uses Cisco's CDP (Cisco Discovery Protocol) at the core of the network. It can also include other network components, but it works best when those are located at the network perimeter. The scripts need SNMP read access for all network hardware. Privileged telnet access can be used to get the MAC address table on IOS and CatOS based switches (faster), but SNMP is sufficient. The configurations are simply read via telnet.
PacketFence is a fully supported, trusted network access control (NAC) system. It includes a captive portal for registration and remediation, centralized wired and wireless management, 802.1X support, layer-2 isolation of problematic devices, and integration with the Snort IDS and the Nessus vulnerability scanner. It can be used to effectively secure networks, from small to very large heterogeneous networks.