Patents went from 3Com to HP to East Texas-based Plectrum LLC.

Patents that only recently were in the hands of Hewlett Packard Enterprise were used last week to sue several companies that build switches and routers, including Cisco (PDF), Juniper Networks (PDF), and Facebook (PDF). A recently created shell company called Plectrum LLC filed the lawsuits in the Eastern District of Texas, a remote judicial district that continues to be a hotspot for patent cases.

The lawsuits are remarkable in part because Hewlett Packard is a company that only recently prided itself on not allowing its patents to be used for offensive purposes, even if they got sold. That attitude started changing about five years ago. Patent office records show that HP transferred the two patents in these lawsuits to Plectrum in September. On Thursday, Plectrum sued Cisco, Brocade, Fortinet, Huawei, Facebook, Extreme Networks, Arista Networks, and Juniper Networks.

The two patents used in the lawsuits originated at the 3Com Corporation, which was bought by HP in 2010, along with about 1,400 patents. US Patent No. 6,205,149 is entitled "Quality of service control mechanism and apparatus," while US Patent No. 5,978,951 describes the use of a "high speed cache management unit" which replaces some software-based systems with hardware in order to reduce latency time.

The lawsuits begin by extolling 3Com's history as an "industry pioneer" and leader in computer networking dating back to its founding in 1979, when computer networking was "nearly non-existent."

The complaint against Cisco accuses the Catalyst 6500 Series Switches of infringing the '149 patent because of how they transmit Ethernet data. Cisco's Adaptive Security Apparatus family of security devices are said to infringe the '677 patent because they allow a secure connection between a user "and servers of a data access network system via a firewall and a router."

For Juniper, Plectrum wants royalties for use or sale of MX Series routers; for Facebook, it's the open-source-based Wedge 100 switches that the patent troll believes are infringing.

Some of the Plectrum lawsuits accuse defendants of having knowledge of the patents-in-suit because of the defendants' own patenting activity. For instance, Cisco mentioned the '951 patent in a disclosure for its own patent application. That leads Plectrum lawyers to argue that Cisco was "willfully blind of Plectrum's patent rights" and took actions that were "objectively reckless."

Plectrum's business address is the one-man Texas law firm of Jon Rowan, and its lawyers are Antonelli, Harrington, and Thompson, a four-lawyer Houston firm focused on patent litigation.

There are a lot of unknowns around the Plectrum lawsuits. One key question: Has HP just decided to monetize patents by selling them off to the highest-bidding troll? Or, as some other companies have, has HP decided to go "privateering," using shell companies to attack rivals with patents and sharing their profits?

HP didn't respond to an e-mailed inquiry asking for comment about the patent transfers and ensuing lawsuits.

They really need to fix this crap.

I'm willing to bet ALL these companies actually paid a licensing fee to 3Com and/or HP previously for the ability to use the technology.