Juniper Networks makes lots of hay about its single-operating-system approach to high-performance networking — saying that using JUNOS across its routing, switching and other application-specific platforms lowers cost and eases operations and management.

Rival Cisco, on the other hand, seems to unveil a new operating system with each product launch, a practice that more and more makes the original version of IOS a distant memory. This year alone, Cisco has unveiled a new operating system for its data center switch and another for its latest generation of edge routers, almost four years after launching yet another for its core routers.

If Juniper is correct, it would seem that Cisco is playing right into its hands.

Not that it looks as if Cisco is in any imminent danger of losing its market dominance. Cisco in 2007 grabbed 82% of the $4.2 billion enterprise-router market, 54% of the $4.7 billion service-provider edge-router market and 55% of the $2.7 billion service-provider core-router market, according to Dell'Oro Group. Juniper ran second to Cisco in every category, with 5%, 18% and 30% shares, respectively. In LAN switching, Cisco had a 71.5% share of the $18 billion worldwide market in 2007, Dell'Oro says. Juniper isn't on the radar screen yet, because its EX line began shipping just last month.

So, in the end, do their operating systems' differences really matter, and could those systems ever really help tip the balance of power in networking? (View companion slideshow: "The battle between JUNOS and IOS")

Juniper thinks so.

"Our customers . . . do not like multiple operating systems, they do not like the fact that they have to . . . figure out what release of the operating system works with which particular product and products," said Juniper Founder and CTO Pradeep Sindhu at the company's analyst conference last month. "Much of this is reflected in operational cost increasing for the customer."

Cisco, meanwhile, claims its various operating system flavors — IOS, IOS XR, IOS XE and NX-OS — are intended to address customer requirements for more consistency across and optimization within product segments.

It also counters that Juniper's single-operating-system claims are misleading. (Read more about Cisco vs. Juniper and Networking's Greatest Arguments.)

"Cisco maintains a consistent user interface across Cisco IOS, IOS XE, IOS XR and NX-OS while addressing segment- or architecture-specific requirements," says Suraj Shetty, senior director of service provider marketing at Cisco. "Seeing Juniper claim only one OS across all products . . . was surprising. They have JUNOS, JUNOS ES, ScreenOS, JUNOSe, IVE OS, NetScreen-IDP, WXOS, CTP and even an OEM OS for their Security Threat Response Manager, and each of those has a different user interface. This places a much larger burden on customers than our approach, which is to address customers' stated needs while maintaining a consistent look-and-feel."

Analysts say users would prefer to work with one operating system but sometimes it's not feasible given their vendors' heritage and direction.

Read related story: "Cisco IOS vs. Juniper JUNOS: The technical differences"

Cisco's legacy

Cisco has a more-than-20-year legacy in enterprise and service provider networking, and IOS has been the company's operating system from the beginning. It was born in the enterprise network environment, where its support for multiprotocol routing helped launch Cisco from a start-up to the $40 billion behemoth it is today.