The two Chinese telecom leaders, plus Ciena Corporation, a U.S.-based global supplier of telecom networking equipment and services, led the WDM Metro equipment, whose revenue surpassed 7 billion dollars in 2017, said Dell'Oro Group, a market research firm on telecommunications, networks and IT industries.

"The WDM Metro systems market jumped in 2017," said Jimmy Yu, Vice President at Dell'Oro Group.

"We all knew that demand for WDM systems in metro applications would increase, but it was a huge surprise to see an 18 percent revenue increase in 2017," Yu added.

Optical Transport revenue increased 19 percent year-over-year in the fourth quarter of 2017, driven largely from increased WDM Metro sales, Dell'Oro Group said in a report, adding that WDM Metro revenue grew 30 percent year-over-year in the same period.

It said the majority of WDM Metro revenue growth in 2017 occurred in two regions -- Asia Pacific, and EMEA, or Europe, Middle East, and Africa.

The top three vendors were Cisco, ECI Telecom, and ZTE, with each seeing their WDM Metro revenue rising by over 40 percent.

ZTE is a Chinese multinational telecom equipment and systems company headquartered in Shenzhen, southern China. It is one of the top five smartphone manufacturers in the domestic market.

Huawei, founded in 1987, is also a Chinese multinational networking and telecom equipment and services company headquartered in Shenzhen. It is the largest telecom equipment manufacturer in the world.