IOS changes could alter face of Cisco routers

Companies can expect to see more modularity and features in Cisco’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 (40G bit/sec) SONET interfaces. IOS-XR is based on a microkernel from QNX Software Systems, which makes real-time operating system software.

IOS currently works as 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 CRS-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 12000 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 services 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.

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