By Benjamin Pimentel

The tech sector was off to a strong start Monday morning, as Cisco Systems posted strong gains after Barclays Capital upgraded the networking giant to overweight.

Cisco (CSCO) shares jumped more than 4% after analyst Jeff Kvaal raised the company's rating, saying, "We expect improving carrier demand, a better Europe, and continued US momentum to drive revenue upside."

Meanwhile, shares of Affiliated Computer Systems (ACS) also jumped more than 15%, after Xerox Corp. (XRX) announced a plan to buy the information technology services company for $6.4 billion.

Shares of Xerox plunged more than 15%.

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 1.7% at 2,126, while the Morgan Stanley High Tech 35 Index (MSH) and the Philadelphia Semiconductor Index (SOX) each rose about 1.9%.

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 about 2%.