Cisco Systems Inc., the No. 1 maker of Internet equipment, agreed to buy the rest of closely held StratumOne Communications Inc. for $435 million in stock to gain semiconductors for high-speed networks. Cisco would swap 6.31 million to 7.72 million shares for the StratumOne shares and options. San Jose-based Cisco took an undisclosed stake in Santa Clara, Calif.-based StratumOne in January. StratumOne makes computer chips that Cisco would use in its most expensive routers, which phone companies need to send data across the Internet. The technology would help Cisco compete with No. 1 phone equipment maker Lucent Technologies Inc. and start-up Juniper Networks Inc. Cisco shares rose 56 cents to close at $62.50 on Nasdaq. Lucent rose $1 to close at $66.69 on the New York Stock Exchange. Juniper surged $16.38 to $115.50 on Nasdaq.