By Benjamin Pimentel

The tech sector rallied Monday, as Cisco Systems Inc. posted strong gains after Barclays Capital upgraded the networking giant to overweight.

Cisco (CSCO) shares jumped 4.4% after analyst Jeff Kvaal raised the company's rating, saying, "We expect improving carrier demand, a better Europe, and continued U.S. momentum to drive revenue upside."

Shares of Applied Materials (AMAT) also gained 3% after the chip tools maker was upgraded to buy by Citigroup.

Meanwhile, shares of Affiliated Computer Systems (ACS) soared 14% after Xerox Corp. (XRX) announced a plan to buy the information-technology services company for $6.4 billion.

Shares of Xerox plunged 14.4%.

Overall, the sector advanced on gains from Cisco and other major networking gear makers, including Juniper Networks (JNPR) and Brocade Communications (BRCD).

The Nasdaq Composite Index (RIXF) added 1.9%, rising to 2,131, while the Morgan Stanley High Tech 35 Index (MSH) and the Philadelphia Semiconductor Index (SOX) each rose about 2%.

Other major tech players were in positive territory, including Google Inc. (GOOG), Apple Inc. (AAPL) and Microsoft Corp. (MSFT).

Meanwhile, Research In Motion (RIMM) was down 3.6%.