Cisco Systems Inc (CSCO.O), the world's largest networking gear maker, forecast current-quarter revenue below analysts' estimates, sending its shares down five per cent in extended trading.

The company said on Wednesday it expected revenue for its fourth quarter to fall between four to six per cent from a year earlier, implying a range of US$11.88 billion to US$12.13 billion.

Analysts on average had expected revenue of US$12.51 billion, according to Thomson Reuters I/B/E/S.

The company also said it extended a restructuring plan to include an additional 1,100 job cuts and expected to take US$150 million in pretax charges.

Cisco said in August it would cut 5,500 jobs.

The company reported its sixth straight decline in quarterly revenue, largely due to a weak demand in its router business.

Cisco, like other legacy technology players, is shifting its focus to high-growth areas such as security, the internet of things and cloud computing.

The company's net income rose to US$2.52 billion, or 50 cents US per share, in the third quarter ended April 29 from US$2.35 billion, or 46 cents US per share, a year earlier.

Excluding items, the company earned 60 cents US per share.

Revenue fell 0.5 per cent to US$11.94 billion.

Analysts on average had expected adjusted earnings of 58 cents US per share and revenue of US$11.89 billion.