IOS changes could alter face of Cisco routers

Companies can expect to see more modularity and features in Cisco Systems Inc.’s IOS software over the next several quarters, as the elements of technology it recently introduced for carriers trickles down to business customers.

The introduction in May of IOS-XR, the software powering Cisco’s CRS-1 terabit router, signals a new direction for IOS, as the software will take on a more modular architecture, with the promise to users of greater stability and easier management. Cisco says this transition for enterprise networks will be gradual, and observers warn that new features might entail hardware upgrades.

IOS-XR is Cisco’s next-generation operating system for its new flagship CRS-1 router, which scales to 96T bits of bandwidth with support for multiple OC-768 (40Gbps) SONET interfaces. IOS-XR is based on a microkernel from QNX Software Systems Ltd., which makes real-time operating system software.

IOS currently works a single piece of executable code on a router; features and functions are added into unique software builds, based on customer needs. The new architecture more resembles a PC or server, with an underlying operating system that runs IP services as separate processes — similar to Microsoft Word running on a Windows PC. Observers say this technique can make routers more resilient and faster.

“We’ll be looking to bring some of those capabilities into the broader enterprise market,” says Martin McNealis, senior director of IOS product management at Cisco. However, what ends up in enterprise IT shops will not be exactly the same IOS-XR used by carriers — or potentially used by carriers, because Cisco hasn’t sold a CSR-1 yet.

“The (multi-chassis) fully distributed (IOS-XR) model that’s appropriate for major service provider backbones is probably overkill for the enterprise market,” McNealis says. “We would look to get (corporations) a version of IOS-XR that is maybe less sophisticated and complex.”

McNealis says this trickle-down effect already started last month with the release of IOS High Availability (IOS-HA) for the Catalyst 6500. A new feature in IOS Version 12.2S IOS-HA lets Catalyst 6500s run dual supervisor cards and failover without losing packets or causing even a millisecond of network disruption, Cisco says. This technology, used previously on Cisco 120000 series routers, improves on previous redundant configurations, which involved a secondary supervisory module rebooting the router when the primary fails.

IOS evolution

McNealis says the road to the new QNX-based IOS-XR began five years ago, when Cisco was acquiring start-ups and churning out new products almost monthly.

“We wanted to get IOS onto many new platforms and adopt it to all different kinds of processors,” McNealis says. “IOS was being stretched in many different ways. In some sense we had been pushing the envelope.”

This led to the now infamous “feature bloat” associated with IOS, where a single software image can include everything from X.25 and ISDN support to VoIP and firewall capabilities.

Instead of making a new IOS from scratch, or adopting an open source platform such as Linux or FreeBSD, McNealis says Cisco chose a third-party microkernel for the new IOS QNX.

“We realized the core competency of our software division was in the IP service’s functionality…we were not fundamentally operating system experts,” he says.

The current IOS software includes millions of lines of code, according to McNealis, but the QNX-based microkernel in IOS-XR has only 80,000 lines.

“That compiles very nicely and lends itself to a variety of smaller form factors,” McNealis says. The fact that IOS-XR is a closed system built from scratch also means the code will be less susceptible to backdoor intrusions or vulnerabilities now associated with IOS, he adds.

Besides routers and switches, IOS touches most of the advanced technology areas Cisco has entered in the last five years, such as security, VoIP, storage, wireless and optical, says Sangeeta Anand, vice-president of product marketing for IOS. She says a shift to a modular-based IOS architecture in corporations won’t cause any drastic changes in how a business IP network operates.

“(Customers) want a commonality of IP services,” Anand says. “The fact that an underlying operating system is Linux-based or QNX-based is quite secondary to them.”

Some users say the software architecture of their routers is a concern.

“My biggest apprehension around IOS is feature bloat,” says Scott Pinkerton, network solutions manager for Argonne National Laboratory, a U.S. Department of Energy Research center near Chicago. He says he’s seen IOS code over the years grow to support “the A to Z set of hardware devices” Cisco offers.

“I really don’t use Cisco (products) A to Z,” Pinkerton says, “so having all those features just isn’t that darn impressive to me.”

One analyst closely watching IOS development says a modular IOS holds great promise for corporations but also holds challenges.

“The key to the next-generation IOS is new hardware,” says Frank Dzubeck, president of Communications Network Architects, an industry analysis firm. “This software will not work with the older hardware.”

As Cisco begins to trickle down IOS-XR-like capabilities to corporations, new router and switch platforms probably will be required, Dzubeck says. But the new capabilities of a modular IOS, where services run like applications on top of a kernel, also could lead to new levels of network reliability and new features.

“You can expect Cisco to get more and more focused on moving up the stack,” Dzubeck says. “And the platform of choice for them will be IOS.”

With firewalling, intrusion detection, caching and VoIP already staple features of IOS, new features such as route control or border session control easily could run as services on top of a new modular IOS kernel.

However, corporations will have to weigh the benefits of what a new IOS would bring versus keeping an installed base of working Cisco hardware and software.

“This is one of those strategic juncture points that happens every 10 years or so,” Dzubeck says. “Mainframes went through this. Even Microsoft (Corp.) went through this,” when it went from DOS to Windows 95 to 2000.

While a new IOS for corporations might introduce fresh bugs and a new learning curve, it would be worth it, Argonne’s Pinkerton says.

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