Cisco's ( CSCO) days as the server industry's collaborator-in-chief may be over, much to the annoyance of Hewlett-Packard ( HPQ), but the networking giant has good reasons for going its own way.

After months of rumor and speculation, Cisco entered the server market earlier this year, a move that placed it in direct competition with long-term partners H-P and IBM ( IBM).

The tremors from the launch of Cisco's UCS technology are still being felt, and have prompted a frenzy of activity from the likes of H-P. This week, for example, the server giant teamed up with Alcatel-Lucent ( ALU) to target the telecom sector, effectively attacking Cisco in its own back yard.

Like a jilted lover, H-P has been telling anyone willing to listen about Cisco's alleged shortcomings, and was quick to launch its UCS rival, the BladeSystem Matrix.

H-P, of course, also has its own ProCurve networking technology to push, and a picture is emerging of Cisco fending off multiple challengers. There has even been speculation that IBM may join forces with networking specialist Juniper ( JNPR) to attack Cisco.

Two other Cisco rivals, 3Com ( COMS) and Voltaire ( VOLT) are also attempting to squeeze the networking giant while it targets the server market.

Despite turning old friends into new enemies, however, Cisco remains a networking behemoth, with the sort of muscle that most tech firms could only dream of. The San Jose, Calif.-based firm exited its recent third quarter with cash, cash equivalents and investments totaling $33.6 billion, and has been working hard to control its costs.

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