The Transformative Operating System Called IOS

December 16, 2009

By Joan Tharp

It is the world's leading network system software, running on an estimated 80 platforms. It is the Internet's primary circulatory system. It is Cisco IOS software, which powers the company's routers and switches.

IOS, originally known as the Internetworking Operating System, played a key role in Cisco's success, but it had a humble beginning. For several years after the company began, it was known just as "the software"—no name, just "the software"—that ran Cisco's routers.

Its eventual name captured the new company's purpose: to create routers that enabled different computers and networks to communicate. (When Cisco was founded, there was an alphabet soup of proprietary networks, including DECnet, AppleTalk, Apollo Domain, Novell IPX, Banyan VINES, IBM SNA, and TCP/IP.)

Building IOS

Several early decisions about how to build IOS gave it staying power, according to two of Cisco's engineering leaders: Joel Bion, SVP of Research and Advanced Development, who joined Cisco 20 years ago; and Kirk Lougheed, a member of Cisco's founding team, its first engineer, the designer of IOS and a Cisco Fellow.

"With IOS, Cisco created one from many, and that's something we still do today."

— Joel Bion, SVP, Research and Advanced Development, Cisco

First, Cisco built the IOS code base so that it was flexible and easy to make quick changes so it would work on multiple platforms, adding functions that customers desired. That let Cisco move faster than its competitors.

"As we were deploying IOS in a customer's account, we'd discover some additional thing they wanted, and turn around and give it to them days later," says Bion. "Over the years, IOS has shown itself to be remarkably extensible."

Another key decision was to have IOS support bridging—at the time a common way to link computers and networks. While bridging and routing each have advantages, the manner in which IOS routes and forwards traffic solved many of the problems with bridging that caused corporate networks to crash, says Bion, and took customers away from companies that just built bridges.

Maintenance Challenges

Cisco's customer-driven focus has been a reward but also a bit of a challenge for IOS over the years.

Cisco has reaped the rewards of this approach because it can quickly build and enhance versions (or trains, as they are called) of IOS for different markets. The challenge, has been in maintaining all those custom-built locomotives, says Lougheed.

But that model is shifting today. In 2008, the company began an effort make it possible to more rapidly deliver similar features across a broad set of platforms for a more consistent user experience. The initiative focused on shifting the architecture by standardized sets of source code that can be shared, which lets the company add functionality and fix bugs faster across platforms, while improving the quality and capability of IOS.

Cisco's Network Software and Systems Technology Group has been making some significant changes in software quality and the result is the evolution of an IOS that is more extensible and flexible.

Currently, Cisco IOS Release15 has a new delivery model and IOS XE is hosting IOS capabilities on top of a Linux kernel to provide High Availability and rapid services integration. IOS XE will continue to evolve so it can accommodate open-source and third-party applications.

"If we don't have to write everything ourselves, we can move much more quickly," comments Lougheed.

Transforming an Industry

If the success of a product is measured by how much it is imitated, then IOS has clearly shown its strength. It sets the standard by which competitive products are designed and even configured.

"Anyone who goes to configure a competitor's product feels very much at home" Bion says. "IOS established the core elements of the language of router configuration"

IOS is also part of Cisco's tradition of transformational thinking.

"The idea that all communication can be supported by homogeneous, lower-level infrastructure is very common today, but it was radical thinking 20 years ago, and it broke the paradigm of how IT networking organizations operated," Bion points out.

Cisco's strategic approach to "purpose-built" (multimarket) solutions has included
best-of-breed applications, sharing information anywhere, any time and any place. This is possible through Cisco's cross-operating systems portfolio, and includes NX-OS and IOS XR, which essentially originated from IOS-based capabilities.

 

Source: Cisco.com