said by tubbynet:a typical cmts (like the cisco ubr series) communicates directly with the modem via the hfc mac address. however, the device that is presented behind the cable modem (be it router or single pc) is also able to be tracked by the cmts (because it is assigned a dhcp "public" ip address). the "overhead" traffic between the cable modem and the cmts can be excluded by the mac address of the destination network frame. this could then be polled using a simple snmp procedure. granted, all of this would need to be coded and rolled out to each market and tested, but a year is a little excessive, even in carrier terms.
said by fAcEtIOUs:said by Mr Matt:Does the Cable Modem really generate 3.3GB/mo? That would really screw someone with a 5GB/mo CAP!
Yes it really does. I measured it by monitoring WAN traffic using DD-WRT firmware in my router. It averages about 10 kbps. And that is with Docsis 1.1. Another user here at BBR says that it is even higher when upgraded to Docsis 2. Who knows what Docsis 3 overhead is like.
just because it is "seen" by your router, doesn't mean its passing through. it is more than likely broadcast traffic or overhead traffic between the cmts and the modem that is passed. a more accurate traffic count would be to measure the bandwidth in/out at your lan port (if you have a single routed port) or at the lan svi (which is what the "lan address" is on the typical soho router). no whether or not the ddwrt software can make this distinction or not either internally or through snmp is another story.
additionally, 3 gigs is *not* going to put you on the "comcast black list". if you are using 253 gigs a month, they aren't going to punish you. while it is a valid concern for the most accurate bandwidth usage/count, its not going to be a deal breaker.
q.
I don't disagree with your conclusions. Just pointing out that the cable modem is seeing this overhead traffic and Comcast may or may not be counting it. And I avg about 10 to 15 GB/mo, so I am not worried about it at all. Just answering someones question about overhead traffic.
