UPDATE 2-F5 Networks Q2 revenue view misses; drags down sector

* Q1 adj EPS $0.88 vs est $0.83

* Q1 rev $268.9 mln vs est $270.3 mln

* Sees Q2 adj EPS $0.84-$0.86 vs est $0.85

* Sees Q2 rev $275-$280 mln vs est $280.7 mln

* Shares down 23 pct after-mkt (Recasts; adds details, share movement)

Jan 19 (Reuters) - F5 Networks (FFIV.O) forecast weak revenue for the current quarter, sending network equipment stocks tumbling in trading after the bell.

Shares of F5 Networks, which has outperformed market expectations for the past seven quarters, plunged 23 percent after it forecast second-quarter revenue of $275-$280 million, below Wall Street's consensus of $280.7 million.

The company, a leader in the network optimization market, has been benefiting from the need to manage network bandwidth amid a surge in mobile and broadband data traffic.

For the January-March quarter, the Seattle-based company expects earnings of 84-86 cents a share, excluding items.

Analysts on average are expecting 85 cents a share, according to Thomson Reuters I/B/E/S.

F5 Networks competes with networking giant Cisco Systems (CSCO.O) and smaller peers like Riverbed (RVBD.O) and BlueCoat Systems BCSI.O.

Shares of Cisco were down about 1 percent, while those in Riverbed fell 9 percent in post-market trading. BlueCoat was trading down 9 percent.

October-December earnings for F5 Networks were $55.7 million, or 68 cents a share, compared with $29.3 million, or 36 cents a share a year ago. Excluding items, earnings were 88 cents a share, topping analysts' estimates of 83 cents.

The company, which had received a takeover offer last year and remains a potential target for tech giants such as IBM (IBM.N) and HP (HPQ.N), said revenue rose 40 percent to $268.9 million. Analysts were expecting revenue of $270.3 million. (Reporting by Siddharth Cavale in Bangalore; Editing by Maju Samuel)