The company grew rapidly through the late 1990s, and at the height of the Internet boom in 2000, 3Com’s stock price rose briefly above $100 a share, only to plummet in the dot-com bust and as a result of management gaffes.

Among those problems was the 1997 acquisition of the modem maker U.S. Robotics and its Palm Computing operation, maker of a line of hand-held electronic organizers. 3Com’s Palm business was seen on Wall Street as a distraction from 3Com’s core businesses, and in 2000, 3Com spun off Palm as separate public company that now makes the Treo line of smartphones.

Since then, 3Com has continued to fall further behind its rival Cisco, which has aggressively acquired technology it needed to keep ahead of other competitors. 3Com, with revenue last year of $1.3 billion, has not posted a profit for six years.

The proposed sale is almost certain to attract close scrutiny in Washington, where Huawei has long attracted suspicions over supposed links to China’s military and intelligence agencies. The company’s reclusive founder and president, Ren Zhengfei, is a former Chinese army engineer.

Michael R. Wessel, a commissioner of the United States-China Economic and Security Review Commission, which was created by Congress to monitor bilateral relations, said that the federal government’s Committee on Foreign Investment in the United States “should take a hard look at this transaction” before allowing Huawei to buy part of 3Com.

Mr. Wessel, who also criticized the Chinese company Lenovo’s acquisition of I.B.M.’s personal computer business three years ago, pointed to reports this month that Chinese hackers had tried to penetrate military computer systems at the Pentagon and in Britain. He said that Huawei’s control of an important network security provider like 3Com would raise national security issues.

If the 3Com deal becomes controversial, as did a bid by Cnooc Ltd. of China for Unocal two years ago or DP World’s effort last year to acquire control of American port facilities, then the transaction may also draw attention to Bain Capital in the race for the Republican presidential nomination.

Mitt Romney, a candidate for the nomination, was the chief executive of Bain Capital for 15 years before his successful run in 2002 to become governor of Massachusetts. His financial disclosure form last month showed that he and his immediate family earned more than $8 million last year from Bain Capital, with stakes in more than 30 Bain Capital funds.