(Reuters) - Activist hedge fund Elliott Management Corp offered to buy network equipment maker Riverbed Technology Inc (>> Riverbed Technology, Inc.) for about $3.08 billion (1.87 billion pounds) in cash, an offer analysts said was likely to be a precursor to a higher bid.

Riverbed shares rose as much as 14 percent to $20.29 on Wednesday, above Elliott's offer price of $19 per share.

Gabelli & Co analyst Hendi Susanto said the offer was below his valuation of $25 per share for Riverbed, based on 14 times 2014 earnings.

Elliott affiliates said in November that Riverbed was significantly undervalued and should consider a strategic review.

The offer represents a 6 percent premium to Riverbed's Tuesday close, but is 26 percent higher than the stock's price before Elliott disclosed a total stake of 10.4 percent in the company in November.

Elliott, run by Paul Singer, is known for publicly agitating for a sale or a board shakeup in companies in which it invests.

The hedge fund said it could raise its offer if it was allowed access to Riverbed's books.

Elliott also has a "go shop" provision in its offer, allowing Riverbed's board to solicit competing bids.

"I don't think Riverbed's management currently wants to sell and this could push the deal higher in my opinion," FBN Securities analyst Shebly Seyrafi told Reuters.

Bloomberg reported in November that Riverbed was working with Goldman Sachs Group Inc (>> Goldman Sachs Group Inc) on a potential sale.

Riverbed has been struggling with the integration of Opnet, a maker of software to manage traffic on networks that it acquired in 2012. Through the acquisition, Riverbed aimed to counter a slowdown in its main wide area network optimization business.

The rise in Riverbed shares since Elliott's November statement has factored in the possibility of a deal, Seyrafi said.

Analysts said potential bidders could be larger rivals such as Cisco Systems Inc (>> Cisco Systems, Inc.), Juniper Networks Inc (>> Juniper Networks, Inc.) and F5 Networks Inc (>> F5 Networks, Inc.) and enterprise software companies like International Business Machines Corp (>> International Business Machines Corp.), Hewlett-Packard Co (>> Hewlett-Packard Company) and Oracle Corp (>> Oracle Corporation).

Riverbed shares were up 12 percent at $20.08 on Wednesday afternoon on the Nasdaq.

(Editing by Kirti Pandey)

By Soham Chatterjee and Neha Alawadhi