Its network throttling implements a two-tier packet queueing system at the routers, driven by two trigger conditions. Comcast's first traffic throttling trigger is tripped by using more than 70 per cent of your maximum downstream or upstream bandwidth for more than 15 minutes. Its second traffic throttling trigger is tripped when the Cable Modem Termination System you're hooked-up to – along with up to 15,000 other Comcast subscribers – gets congested, and your traffic is somehow identified as being responsible. Tripping either of Comcast's high bandwidth usage rate triggers results in throttling for at least 15 minutes, or until your average bandwidth utilisation rate drops below 50 per cent for 15 minutes. The Comcast two-tier traffic throttling system enforces different quality-of-service levels. Internet packets to and from a specific subscriber are assigned 'Priority Best Effort' (PBE) queueing by default, and the traffic rate is throttled by switching packets to lower priority 'Best Effort' (BE) queueing.
So downloading or uploading a large file is going to be a bit tricky then