Juniper Networks

(JNPR) - Get Report

was selling off in premarket trading after the company sharply lowered its fourth-quarter revenue and earnings guidance, reflecting caution from carrier customers due to the weak economy.

The IP Infrastructure provider expects fourth-quarter revenue to be $150 million to $155 million, down from original guidance of $200 million. Pro forma earnings per share are now expected to be 5 cents. Wall Street analysts had been expecting 10 cents a share, according to Thomson Financial/First Call.

Shares of Juniper were falling 20.2% to $18.30 in Instinet trading after this morning's announcement.

A similar warning from rival

Ciena

(CIEN) - Get Report

last week led to a rout in networking stocks. Ciena said first-quarter sales would be 30% to 40% below estimates and said it might lose money in 2002. Further pressure came to bear when

Qwest

(Q)

, a major purchaser of networking gear, said it would spend only $4.2 billion to $4.3 billion on capital equipment next year, down from a September estimate of $5.7 billion.