But the Chinese manufacturer said the copying was inadvertent and involved far less code than Cisco claims. Huawei also said the offending code has since been removed.
Even so, Cisco said in a statement, the admission is "further evidence that Huawei has unlawfully acquired and used Cisco's intellectual property."
Cisco sued Huawei in U.S. District Court for the Eastern District of Texas on Jan. 23, alleging that Huawei violated at least five Cisco patents and copied Cisco's Internetwork Operating System (IOS) source code, using it in the operating system for its Quidway routers and switches. Huawei's system contains text strings, file names and bugs identical to Cisco's source code, Cisco is claiming.
Cisco's lawsuit alleges that Huawei copied up to 1.5 million lines of software code. In its latest court filing, Huawei said an employee inadvertently used about 2 percent of the 1.5 million lines of code inside Huawei's VRP line of routers.
The "limited amount" of Cisco copyrighted code was provided by someone other than a Cisco or Huawei employee, according to the 53-page filing. The source wasn't further identified.
It was on a disk passed from one Huawei employee to another, who then incorporated the code into what he was working on, according to the paperwork.
Huawei, based in Shenzhen, China, has a wide reach in Asia and recently entered the U.S. market, challenging Cisco on the pricing front. It's now working with Cisco competitor 3Com to deliver new networking gear to businesses.