Norte filed for bankruptcy protection in January and has decided to sell of its assets. The bidding for North America’s once biggest telecom equipment maker has gained much attention from the international business community. Now new bidding is underway for Nortel’s optical networking and carrier Ethernet business.

Nokia Siemens Networks and a private-equity company One Equity Partners have jointly placed their bid. This comes to challenge Ciena Corp.’s $526 million bid for the assets. Ciena actually offers $390 million in cash and 10 million Ciena shares.

Bids for Nortel’s Ethernet business were due Nov. 17 but the company has delayed the initial deadline because other bidders have expressed their interest. Nortel said, however, that the final auction will be held tomorrow on Nov. 20.