Dow Jones Newswires notes that shares of Ciena jumped Tuesday on speculation Nokia Siemens Networks (NSN) could be interested in buying the network-systems maker. Late last year, Ciena succeeded in winning the auction for Nortel Networks’s Metro Ethernet Networks business, which contains optical networking and carrier Ethernet assets. NSN, a joint venture between Nokia and Siemens AG, also made a bid for the assets and later tried to reopen the auction, which was rejected by a court.