A U.S. International Trade Commission (ITC) judge ruled today that Arista has infringed on three Cisco patents, including one that pertains to SysDB, an important piece of software that pervades Arista’s switch portfolio.

Both companies are reacting via their blogs, with Cisco claiming the decision is "the beginning of the end" and Arista musing about "the length that Cisco has gone to misrepresent our actions."

The ruling, delivered by Administrative Law Judge David Shaw, arrived after a delay due to recent snowstorms. Details of his decision will arrive sometime in the next 30 days.

The ruling pertains to an ITC case covering six patents that Cisco claims Arista has violated. One patent was dropped from the case earlier, and Shaw ruled that Arista did not violate two others.

Cisco is hoping the case leads to an injunction against the importation of Arista's products. But the case isn't complete yet. A final determination from the ITC is due on June 2, to be followed by a presidential review with a deadline of Aug. 2.

Six other patents are the subject of a separate ITC investigation, in which the judge's decision is due on April 26.

Separately, a copyright lawsuit, in which Cisco claims Arista's use of command-line interface (CLI) commands is a violation, is scheduled for trial in U.S. District Court in November. In this lawsuit, Arista has filed a counterclaim accusing Cisco of violating antitrust law.

A page on Arista's website conveniently summarizes all these dates.

Arguably the most crucial of the three patents in today's ruling is No. 7,162,537, which concerns "externally managing router configuration data in conjunction with a centralized database."

That's part of what Arista does with SysDB, a database that stores the state of Arista's switches and allows them to share state information with one another. This particular patent strikes at the heart of Arista's architecture.

The two other patents that Arista was found to be violating pertain to private VLAN features in Arista's switches, according to Cisco's original court complaint, which was filed in December 2014.

Often in these kinds of lawsuits, the defendant will create a software workaround that brings the products into compliance, thus saving them from being banned from importation. (Tech products tend to be built and/or assembled overseas, which is why the ITC can get involved in these patent disputes.) Arista didn't submit any workaround designs during the ITC hearing, Cisco General Counsel Mark Chandler notes on the company's blog.

Arista has offered a simple statement in reaction to the ruling: "Our primary focus is the continued supply of products to our customers. We respect the administrative process and the tireless work of the ALJ in this initial determination."

The company has also posted a blog in which Kenneth Duda, an Arista founder and the company's CTO and senior vice president of software, takes Cisco to task for its tactics. It reads in part:

Much like with the CLI, when we entered the industry in 2008, we offered these features like all other vendors because that is what our customers expected and no one ever claimed to own exclusive rights to such industry features. In some cases, these features weren’t even implemented by us but by our vendors. Now Cisco claims to have patents that prevent anyone other than Cisco from implementing such standard features and accuses Arista of "stealing" patented technology.

On Cisco's blog, meanwhile, Chandler states that "Arista can no longer support claims to customers, resellers, and the market that they created products from 'a clean sheet of paper,’ " adding that "none of the patents have been proposed for or adopted as industry standards."