The NetDecision Traffic Grapher
(http://www.netmechanica.com/products/?prod_id=1022)
monitors network and bandwidth usage as well as various other network
parameters like memory usage and CPU utilization, providing system
administrators with live readings and periodical usage trends to
optimize the efficiency, layout, and setup of leased lines, switches,
routers, firewalls, servers, and other network components.

NetDecision Traffic Grapher is an easy to use software that monitors
network parameters via SNMP or using custom scriptable polling agents.
It allows you to quickly and easily set up and run a monitoring
station for networks. With just a few mouse clicks you can log the
amount of data flowing through routers, monitor CPU and RAM
utilization, check disk space usage, etc.

The most common case is monitoring the bandwidth usage of leased
lines, routers, and firewalls via SNMP. You can also monitor many
other aspects of your network environment and computer
infrastructure.

NDTG provides out-of-the-box graphs and dashboards for CPU
utilization, memory usage, disk space usage, interface utilization,
service response times, interface errors etc. This helps users gain
better visibility into the performance of servers, routers and
switches and the overall network.

NDTG makes network performance monitoring effortless to set up and
users can quickly get live, daily, weekly, monthly, annual or custom
period graphs out-of-the-box.

NDTG allows users to setup monitoring of custom SNMP MIB variables.
Traffic Grapher makes network performance monitoring truly vendor-
independent. You only need access to the SNMP MIBs provided by your
vendor. Traffic Grapher allows you to monitor critical parameters of
any device and setup thresholds.

NDTG simplifies the process of setting up initial monitoring
configuration by discovering network devices such as routers,
switches, servers, printers etc automatically.