[bradleyland]

It's not pretty, but I use Routers2, which is a layer on top of MRTG. We have TimeWarner's commercial cable internet service, and our latency spikes to ~800ms at a regular and consistent interval. I've been 10 rounds with TimeWarner over the issue, but they refuse to acknowledge that it's an issue because they have no latency SLA. We ended up bringing in a second Windstream Ethernet over copper circuit for our VoIP application because the TW circuit latency was so bad.

I have a local VM with Routers2 installed, which pings our LAN router, the TW modem, the first TW hop, and one of our VMs at Linode. The latency spikes start at the first TW hop. Routers2 provides great insight in to how TW is performing.

You can get Routers2 here: http://www.steveshipway.org/software/