On 1/9/16, 12:04 PM, "NANOG on behalf of Robert Webb" <nanog-bounces@nanog.org on behalf of rwebb@ropeguru.com> wrote:

Unfortunately, providers like Comcast, yes, I know they aren't wireless, but their usage meter is a joke and a proprietary based joke at that. I do not think I have ever seen anyone from Comcast willing to describe exactly how their meter works and what is and is not counted towards usage. I am not a wireless expert, but my guess is that it would be even more difficult to accurately track usage on wireless given the portable nature.

Since my day job is at Comcast and part of that job is ensuring that the usage meter is technically accurate I figured I would chime in. A few bits of information that may be helpful follow below. **I am happy to answer any questions you or others have.** And I have also copied our independent auditor should there be questions for his firm. 1 - Comcast does byte counting via the IPDR standard (IP Detail Records). I would think any other DOCSIS-based network that performs byte counting would also use IPDR (and all the ones of which I am aware do so). You can find some more information about the IPDR specification here: https://en.wikipedia.org/wiki/Internet_Protocol_Detail_Record https://www.incognito.com/tips-and-tutorials/faq-bandwidth-monitoring-with- ipdr/ http://www.dslreports.com/r0/download/1603814~d44a19780841cdc79abf840b6066d 52d/ipdr-usage-counters.pdf http://www.cablelabs.com/wp-content/uploads/specdocs/CM-SP-OSSIv3.0-I14-110 210.pdf 2 - Comcast first made mention of the use of IPDR in a 2008 FCC filing, as part of a deployment of a protocol-agnostic congestion management system. See these documents: http://downloads.comcast.net/docs/Attachment_B_Future_Practices.pdf https://tools.ietf.org/html/rfc6057 3 - Comcast engaged a 3rd party auditor called NetForecast (http://www.netforecast.com/) to regularly, independently audit the accuracy of our usage meter. We usually announce those audits on our Network Management page (ex: http://networkmanagement.xfinity.com/index.php/8-network-management-news/55 -2015-comcast-usage-meter-accuracy-report) and NetForecast publishes these reports on their website. See the following documents: - First accuracy report, 2009: http://www.netforecast.com/wp-content/uploads/2012/06/NFR5101_Comcast_Usage _Meter_Accuracy_Original.pdf - Second accuracy report, 2010: http://www.netforecast.com/wp-content/uploads/2012/06/NFR5101_Comcast_Usage _Meter_Accuracy.pdf - Third accuracy report, 2014: http://www.netforecast.com/wp-content/uploads/2014/05/NFR5116_Comcast_Meter _Accuracy_Report.pdf - Fourth accuracy report, 2015: http://www.netforecast.com/wp-content/uploads/2015/06/NFR5120_Fourth_Comcas t_Meter_Accuracy_Validation_Report.pdf - ISP best practice report: http://www.netforecast.com/wp-content/uploads/2015/06/NFR5119_General_ISP_D ata_Usage_Meter_Specification.pdf 4 - In terms of what is counted, all Internet traffic is counted (what is now known as Title-II traffic). Title-VI video traffic and Xfinity Voice traffic, which may use the IP protocol but are not Internet services, are not counted. Enjoy the rest of your weekend, Jason