Those in telephony know the Call Detail Record (CDR) or the Station Message Detail Record (SMDR). Now in the IP world we have the Internet Protocol Detail Record (IPDR). This measures your IP network traffic volume. Comcast is trialing this feature of the Cisco 10000 CMTS (Cable Modem Termination System) for residential customers.Comcast has an Acceptable Use Policy (AUP) that defines an allowance of 250GB per month. It appears that the initial application of the IPCR for residential customers is to provide online feedback to the customer about the usage during the month.
Peter Sevcik of NetForecast published a study in December 2009, "Comcast Usage Meter Accuracy." This study for Comcast is an independent evaluation of the metering technology and the report it generates. The study determined that the metering was accurate to .5%. The metering specification is managed by the TeleManagement Forum (TM Forum). A Management Information Base (MIB) is defined for DOCSIS that specifies how traffic is counted for the IPDR.
The traffic is measured by the CMTS for each cable modem it serves. There is a differentiation in measuring traffic. Internet traffic is counted but not Comcast's Digital Voice, digital video and other non- Internet traffic services provided by Comcast. This poses an interesting issue for the customer. If the traffic is for third party voice, like Vonage or video services like Netflix, then this is Internet traffic by Comcast's definition and will be counted against the allowance. This favors Comcast's services.
The count includes all the protocol overhead for IP and higher level protocols but not the Ethernet overhead. It also includes minor management traffic from cable modem health checks and SNMP polls. These last two types of traffic account for less than 1GB per month according to the study.
The traffic reports are not in real time. Traffic reporting has a time lag of about 15 minutes. The raw data, traffic records, is fed to the Active Resource Manager (ARM). The ARM feeds the information to the Comcast Enhanced Mediation Platform (CEMP). The CEMP adds the up- and download totals and rounds down the total to the nearest GB. The meter is reset each month back to zero state, but the report shows 1GB, not zero. The clock starts at GMT time, not local time. The customer can access the metered information, but the metering portal is about 3 hours late in reporting the usage.
The metering will include a lot of traffic that the customer may not know about such as a DVR, WiFi and other devices connected to the cable modem in addition to the PC. TCP retransmissions are also counted, adding to the traffic. Other overhead such as VPN and SSL is counted. When the traffic consists of content delivered by a source server and CDN, then there is more traffic counted.
The report goes on to discuss unexpected traffic. Unexpected traffic can be generated by:
* Game consoles * Networked printers * Cameras * Smart phones * DVRs * Unauthorized WiFi traffic * Automated downloads such as software updates, patches and security information * Automated file backups * Movie preloads such as trailers
If the PC is the traffic generator, then I expect that there will be applications that can be loaded into the PC that will provide real time locally (PC) generated reports. Once this happens and there is a discrepancy between the Comcast report and the PC resident report generator, then we can expect a lot of conflict as to who is right. It is very likely that the Comcast report will show more traffic than the user expects. The unexpected traffic, unknown to the user, will be the source of the difference.
Now suppose we extend the metering concept to the enterprise. Once this metering is enabled, I think we can expect that small businesses on Comcast Internet service will eventually be metered. As Comcast sells more business services, then the medium enterprise can expect metering. The metering will allow Comcast to raise their revenue through overage charges or through higher charges for a bigger traffic allowance.
Another thought is what else the CMTS could collect as information. What if Comcast collected the user's information when they access competing voice and video services? Then Comcast could target these users with focused advertising to get them to migrate to the Comcast services. If Net Neutrality rules are not enhanced, then Comcast could penalize the competing service and slow down the access or limit bandwidth. These are speculations that would be worth considering for the enterprise itself as well as its teleworkers. Although I mention Comcast, my points are valid for any Internet cable service.
