Juniper continued to take share from Cisco in service provider routing, especially in the core, in the fourth quarter of 2004.

Though it has not yet released detailed numbers, market researcher RHK says Juniper gained 5% share during this period on core router revenue growth of 36%. On an annual basis, the market share swing was a more modest 2% in Juniper's favor, according to RHK.

The core was especially hot in 2004, according to Dell'Oro Group, growing 66% to $1.2 billion. The numbers from Synergy Research, meanwhile, were a bit more conservative: The firm found that core routing revenue grew 36% annually to $1.7 billion and 8% sequentially in Q4 to $473.3 million.

Synergy also found that Juniper's share in the core grew from 29.3% in Q3 to 31.1% in Q4, and from 22.6% to 27.6% year-over-year -- the inverse of  RHK's findings. Cisco's share fell from 68.9% to 67.3% sequentially, and from 73.6% to 70.2% on an annual basis, according to Synergy.

The combined core and edge service provider router market grew 31% year-over-year, from $2.9 billion in 2003 to $3.8 billion in 2004, Synergy found. Cisco's revenue increased 24% during that time, to $2.4 billion; Juniper's, meanwhile, leapt 66%, to $975.6 million.

Cisco's combined core and edge market share slipped from 68.5% in 2003 to 64.7% in 2004, while Juniper's jumped to 26% from 20.5%, according to Synergy. Sequentially, Juniper's share reached 30% from 26.4%, while Cisco's dropped from 64% to 61.5%.

In terms of revenue, Cisco's fell 3% sequentially to $616.3 million, while Juniper's rose 15% to $300 million, according to Synergy.

The combined broadband aggregation and core router markets increased 37% in 2004, driven by triple play and scalable MPLS deployments, Synergy says.