Feature Story

May 25, 2004

The company that wrote the book on IP networking is now starting a new chapter in the history of communications.

Cisco Systems has created the Cisco Carrier Routing System (CRS-1), the culmination of the most ambitious project in the company's 20-year history. The four-year, $500 million undertaking has produced a revolutionarily powerful, scalable, reliable, and manageable Internet protocol (IP) backbone router. IP backbone routers are the devices that control the flow of the information coursing through the largest arterial connections on the Internet, managing where and how massive amounts of bits and bytes get delivered.

CRS-1 is the router that will help telecommunications companies complete the move from the analog era to the digital era-from the era of the phone to the era of the Internet. It is the industry's first router to scale to over 90 terabits of bandwidth capacity, as well as providing the industry's first true 40 gigabits-per-second (Gbps) fiber optic interface. That's more than four times greater than the next fastest connection possible. A single CRS-1 system can provide an 850 kilobits-per-second (Kbps) connection to every household in the United States, transfer the entire collection of the U.S. Library of Congress in 4.6 seconds, or make 3 billion telephone calls per second.

News@Cisco spoke with the two primary architects of the Cisco CRS-1, Tony Bates, vice president and general manager of Cisco's carrier core and multi-service business unit, and Dan Lenoski, the vice president of engineering responsible for CRS-1. They discussed the unprecedented advances of the CRS-1, what the CRS-1 means to service providers, and how the new router will influence communications for the next decade.

What prompted Cisco to build the Cisco CRS-1?

Tony Bates: We built the Cisco CRS-1 to help the largest telecommunications companies in the world-our customers-create networks for the Information Age. Cisco designed the CRS-1 to be the foundation of converged packet infrastructures for the next 10 to 20 years. Despite the bursting of the tech bubble, Internet traffic continues to expand rapidly, and bandwidth demands continue to increase pressure on the infrastructures of the largest service providers. Applications such as IP telephony and streaming video are driving customers' interest in DSL, cable modems, and broadband business connections. At the same time, telecommunications companies are looking to consolidate all their network traffic-phone service, data, and video-onto one network infrastructure. The CSR-1 provides the horsepower and intelligence to manage all traffic on one IP-based network.

What makes the CRS-1 unique?

Tony Bates: It terms of networking equipment, the CRS-1 is about as unique as you can get. Cisco-nor any other vendor in the industry-has never built a router remotely resembling the CRS-1. We didn't hold back on any aspect of its functional capabilities. We aimed to build the most powerful, most scalable, most reliable, most adaptable, and most manageable router the industry has ever seen. It is the first router that can be wholly responsible for running all forms of communications at the heart of the world's largest networks.

The CRS-1 provides unprecedented performance, offering the industry's first true OC-768 bandwidth links, which deliver 40 Gbps connections. The previous benchmark was 10 Gbps. It can also scale from handling a volume of 1.2 terabits per second (Tbps), that's 1.2 trillion bits per second, to over 90 Tbps, far surpassing the next fastest IP router on the market. The average "life expectancy" of typical networking equipment has been three years. We have designed the CRS-1 to last at least 10 years, and as much as 20 years.

Dan Lenoski: In conjunction with such unprecedented performance, the CRS-1 sets a new standard for router reliability and availability. Basically, the CRS-1 will continue to operate during any unplanned fault as well as any planned maintenance or repair. It offers the same dependability that telecommunications companies and their customers have come to expect from telephone equipment. And the CRS-1 isn't just all brawn and no brains. Far from it. The silicon is highly programmable, providing telecommunications companies with the freedom to tailor the CRS-1 to almost any application or service they may want to sell. We created the CRS-1 to provide all of these advantages while also lowering management overhead. Since the CRS-1 scales as one contiguous routing system, management complexity does not grow as bandwidth grows, traditionally a serious challenge to communications companies trying to keep pace with the expansion of the Internet.

How will the CRS-1 help telecommunications companies run their networks and their businesses better? How will it help them reduce costs and increase profits?

Dan Lenoski: Cisco built the CRS-1 in close collaboration with our major telecommunications company customers. Their needs drove our design of the router. So, we are confident the CRS-1 will provide carriers with the router that they have been hoping for. The CRS-1 addresses four concerns of telecommunications companies: convergence, capacity, complexity, and capabilities. Most importantly, it lets service providers converge their multiple network infrastructures for voice, data, and video onto one infrastructure, in the process reducing ongoing management costs as well as reducing redundant capital outlays. Secondly, the CRS-1's capacity-both bandwidth and scale-greatly reduces the equipment "churn" that has been limiting telecommunication operators' profits. To make the CRS-1 last a decade or more, we designed it to incrementally and seamlessly grow as bandwidth demands grow. The basic CRS-1 can handle 1.2 terabits of traffic. But then network operators can add dozens or more of these chassis. Such capacity means network operators can consolidate functions currently on different routers, reducing both the complexity of operations and the number of non-revenue generating ports that connect the multiple routers. The CRS-1, though composed of multiple chassis, is a single system-regardless of how much it expands-controlled by one operating system and management lattice. Finally, the CRS-1's intelligence and adaptability give telecommunications companies the capabilities to offer a wide variety of services, graduated for a full spectrum of performance levels. And the CRS-1's programmable silicon will let the router evolve as customers require new services and applications.

How will CRS-1 benefit business and individuals, the customers of telecommunications companies?

Tony Bates: In my opinion, the "killer application" everyone talks about is, and will continue to be, bandwidth. Without bandwidth, none of the exciting new applications coming from the Web would be possible. Bandwidth makes services such as video streaming, video conferencing, animation, gaming, IP telephony, and remote storage viable. So, in short, the CRS-1 means more bandwidth for everyone. Just one CRS-1 system, for example, can provide an 850 kilobit-per-second (Kbps) connection to every household in the United States. And as part of that capacity, customers will not only be able to use more bandwidth but also at a lower cost.

Dan Lenoski: The CRS-1 also will allow service providers to deliver a greater variety of services more easily while being able to rollout new services more quickly. This is especially true for any multimedia type application. A converged, IP network is far more capable of combining the different types of communications-voice, video, and data-since each one is digitized in data packets. This makes the creation of new multimedia applications much easier than with traditional analog communication systems.

What were the most noteworthy technical challenges to building the CRS-1?

Dan Lenoski: There are many, many innovations in the CRS-1, but if I had to pick just a few, they would be the new forwarding engine chip-called the Silicon Packet Processor (SPP)-the scalable switch-fabric that connects the whole system together, and the new operating system. The CRS-1's forwarding engine, which makes the complex decisions about how to process, queue and forward incoming data at 40 Gbps, is powered by 188 32-bit RISC microprocessors running in parallel. IBM, which manufactured the chip for us, told us that it is twice as complex as any other ASIC that they had made. By utilizing two SPP chips per line card, the CRS-1 provides computing power only matched by the world's most advanced supercomputers. The other major hardware innovation is the switching fabric that allows CRS-1 to scale from sixteen 40 Gbps line cards, or network links, to over one-thousand line cards and can achieve an unprecedented switching capability in excess of 30 Tbps per chassis.

The CRS-1's operating system is another landmark. Until now, the Cisco Internetworking Operating System, or IOS, has managed almost all Cisco equipment. Since our first router 20 years ago, the IOS has been the operating system that has run the Internet. But because the CRS-1 was such a departure in design-fully distributed, fully modular-we needed a new IOS to run this type of machine. Working in the shadow of a legend was daunting, but I think what we came up with does IOS proud. Officially called IOS XR, the CRS-1's operating system uses what is known as a distributed "microkernel" architecture. This approach breaks the operating system into discrete components that are distributed throughout the router system and allows the software to scale with the size of the machine. This also means that the IOS XR keeps working at full-speed during maintenance, repair, or upgrade activities, as well as being able to run multiple functions or applications simultaneously without worries of one application affecting the performance of another one.

What benefits will the CRS-1 bring to Cisco?

Tony Bates: We certainly aim to sell a few of these routers. Obviously, this is an extremely advanced machine, and we designed it for the world's largest telecommunications companies running the world's largest networks. But over time, it will be viable for a greater array of service providers. It is interesting to note that back in 1995 people questioned how many 12000 Series routers we would sell. The 12000 Series was Cisco's first router designed specifically for large telecommunications networks. Despite early skepticism, the 12000 Series went on to become one of the most successful products in the history of networking. We have sold over 25,000 of them, and the 12000 Series has become the Internet's most popular backbone router. The CRS-1 is the product that begins the next 20 years of our efforts to improve modern communications.

Dan Lenoski: It is important to note that the research and development that we put into the CRS-1 has generated a vast spectrum of innovations Cisco can use throughout the company. The work on the CRS-1 will have an incredible ripple effect throughout the organization. The new IOS, the new switch fabric, the silicon advances, and the dozens of other innovations in the CRS-1 will directly and indirectly boost the quality of all our products for years to come.