Server-load balancing is on the up, according to analysts at the Dell'Oro Group. The segment jumped 15 percent on revenues last quarter to a record $264 million worldwide - equivalent to over $1 billion a year.

In addition, the analysts said, Cisco knocked F5 off the number one spot.

Dell'Oro vice president Seamus Crehan attributed both the growth and the change of top vendor to new products from Cisco and the vendor's fiscal year end.

He said that F5 was still the second largest vendor, while Citrix and its NetScaler range third. Following those three were Nortel, Radware and Foundry.

Vendors and analysts alike typically lump server load balancing in with other technologies, such as WAN optimisation, application acceleration and traffic management, as part of a larger 'application delivery' sector.

But while it is usually the newer technologies that get the headlines - and while mergers and acquisitions have shown that there is definitely synergy between these different product classes - it seems clear which application delivery technology is in the greatest demand.

"Despite vendor acquisitions in many adjacent technologies such as WAN optimisation, server load balancing remains the largest portion of the application delivery market," said Crehan.

He added, "However, these acquisitions are very strategic for companies who want to offer a holistic solution."