OpenNMS is great to run in addition to a traditional monitoring system.
Your traditional monitoring systems have hand-selected features to monitor and alert for. OpenNMS will just go out and discover everything you have (and graph everything without any intervention too).
You probably aren't monitoring all the statistics on every interface of your switches (what? people have switches?), but just throw OpenNMS at your networking management subnet and it'll pick up everything for later review.
You can use OpenNMS for alerting and inventory tracking, but I prefer more extensible tools for those. Just use OpenNMS as a largely hands-off sanity check of your existing monitoring and graphing systems.
Your traditional monitoring systems have hand-selected features to monitor and alert for. OpenNMS will just go out and discover everything you have (and graph everything without any intervention too).
You probably aren't monitoring all the statistics on every interface of your switches (what? people have switches?), but just throw OpenNMS at your networking management subnet and it'll pick up everything for later review.
You can use OpenNMS for alerting and inventory tracking, but I prefer more extensible tools for those. Just use OpenNMS as a largely hands-off sanity check of your existing monitoring and graphing systems.