Comcast, you've got company.

A new study from the Max Planck Institute in Germany suggests that Comcast Corp. isn't the only ISP that's been throttling peer-to-peer (P2P) traffic. The study also has Cox Communications Inc. and Singapore's StarHub Pte. Ltd. on the list.

Krishna Gummadi of the Institute told the Associated Press that the tests did conclusively show that Cox and/or Comcast were "blocking" P2P, because it's possible that international carriers could be disrupting traffic as it made its way from the MSOs to the servers in Germany used to conduct the tests.

"To ensure the best possible online experience for our customers, Cox actively manages network traffic through a variety of methods including traffic prioritization and protocol filtering," Cox said in its response to the AP.

The study, which based its findings on data retrieved from 8,175 volunteers who used a downloadable test tool, said most (573 of 599) U.S. "hosts" that observed "blocking" are located in Comcast- and Cox-run networks. In Singapore, all blocked hosts were connected via the StarHub network, according to the study.

Comcast has been the subject of passionate complaints and a Federal Communications Commission (FCC) probe into its network management practices. (See FCC Eyes Comcast's P2P Policies.) It has acknowledged delaying some P2P traffic during periods of congestion but has vehemently denied it is blocking applications, including P2P. (See Comcast Defends P2P Management .) It has, however, announced plans to migrate to a "protocol agnostic" capacity management system by year-end. The operator has not released details about the new platform, but it's believed that it will ensure that P2P connections are not reset. (See Comcast Caves In to P2P Pressure.) Reports have also surfaced that the MSO is considering a monthly 250 gigabyte consumption ceiling. (See Comcast Caps Coming? )

The latest allegations quickly drew another "Network neutrality" plea from Free Press policy director Ben Scott. "Congress and the FCC must urgently pursue the complaints against network providers. Consumers have no reason left to trust their cable company," he said in a statement.

— Jeff Baumgartner, Site Editor, Cable Digital News