Case Technology White Paper

Why Use Linux Based Routers?

Linux router overview

The router market are buying routers that are made from commodity off-the-shelf components. These commodity routers are fast, inexpensive, and can handle a wide range of networking applications. When compared to routers offered by the industry's largest manufacturers, commodity routers can cost one half, one quarter, even one tenth the price.

For simple routing applications, some organizations choose to build their own routers using in-house engineering talent, off-the-shelf hardware, and Open Source operating systems. Others purchase commodity routers from commercial manufacturers like Case Communications and their US partner ImageStream because they want the best available product design, testing, price, performance, reliability, compatibility, warranty, and support. The right approach for your organization depends on the complexity of the application, your in-house engineering capabilities, and your tolerance for surprises.

Commodity routers can be built on top of many different operating systems. For example, some router manufacturers license a proprietary operating system such as VxWorks or the LynxOS to run their products. Others use FreeBSD or NetBSD because they have no associated license fees, and the source license makes it easy to protect any proprietary software that may be developed. Cisco Systems uses its own proprietary operating system called IOS®, which cannot be licensed for use in low-cost commodity routers.

Case Communications and ImageStream chose to run Linux on their commodity routers for several reasons. First, Linux is a widely used operating system for network server applications and embedded products. It has been the fastest growing UNIX-style operating system for several years, and its popularity ensures that there are many engineers, technicians, and administrators who have the skills required to maintain Linux routers. Second, they chose Linux because of its Open Source pedigree. Linux is a freely licensed Open Source operating system, and it has no incremental software license fees for developers or end users. Linux also offers the widest range of Open Source networking utilities, and it provides an efficient multi-tasking multi-processor kernel with fast TCP/IP packet routing and filtering.

Commodity hardware

Everyone knows that standard PC components continue to get faster and less expensive. The 450 MHz Pentium II that was Intel's top-of-the-line processor in early 1999 cost more and provided a small fraction of the CPU performance that Case Communications routers deliver today. When USA vendor ImageStream first started manufacturing commercial routers, the Pentium II 450 was the fastest processor available from Intel. Since then, vendors such as Case Communications and ImageStream have upgraded their top-of-the-line router performance by using new processors and memory subsystems that can execute the same instructions more than 16 times faster.

When you look at the components used in a Cisco router, you will typically find a pile of really cheap parts. This is probably true about all Cisco routers until you get into higher-end products like the 7600 and 12000. To its credit, Cisco is just like any other router manufacturer that constantly works to minimize its manufacturing costs. Unfortunately for its customers, Cisco not only puts low-performance parts in its products, but it also chooses to pocket the savings instead of passing those savings along to its customers. As a result, many Cisco customers have become frustrated with Cisco's high prices and mediocre to poor product performance.

Case Communications routers take advantage of off-the-shelf processors that typically double in performance every 18 months (refer to Moore's law). In contrast, only high-end Cisco routers starting at the 7000 series provide a modular processor card that can be upgraded over time. So if you are purchasing Cisco routers at the 7000 series level or above, Cisco normally takes about three years to deliver a new processor upgrade, and historically those upgrades have only doubled the performance of the fastest processor available for the platform. This rate of advance in processor performance is about one half the rate of advance for standard PC hardware.

The processor in a Cisco router will vary from model to model, but you can expect to have the bottom end of the Cisco product line provide around 100 MIPs or less of integer processing power. In the 3600 series, you get less than 400 MIPs; in the 3700 series, you get 700 MIPs or less; and in the 7500 series you get 1,000 MIPs or less. Data for the 1800, 2800, and 3800 series routers is not currently available.

Comparing raw CPU performance, Case Communications TransPort router provides 688 MIPs of integer processing performance. The R1 is one step above the TransPort, and it delivers 1219 MIPs, which is faster than Cisco's fastest 7500 series processor. When you compare routers like the Cisco 7200/NPE-G1 and Case Communications Enterprise Router, you will see that Case Communications flagship router provides more than 4 times the raw processing power and up to 16 times the bus bandwidth of the Cisco.

Unfortunately for Cisco, the raw processor performance measured in MIPs does not tell the whole story when it comes to processor performance. This is because processor performance comparisons in MIPs do not factor in the significant performance advantage that CISC CPUs offer.

Cisco's RISC processors require many additional clock cycles to perform the same operations that are performed in a single clock cycle by x86-compatible CISC processors. This means that if CISC and RISC CPU performance in MIPs were equal, the CISC processors would still deliver better performance than their RISC counterparts. In fact, the CISC processors would do the same work in about half the time, which means that the Enterprise Router provides closer to 8 times more processing power than the 7200/NPE-G1.

The PC market is the largest volume market for high-performance processors, memory, data buses and logic chips. Demand from the PC market directly pushes the development of faster hardware, but in many cases these advances never become available for the embedded RISC processors used by Cisco.

Proof of concept

The router market wants better value for money, and this is reflected by the market's acceptance of these Linux based routers which provide superior features and performance at a fraction of the cost of Cisco products. In addition, Case Communications success proves that commodity routers are here to stay.

Now that the router market has an E1 router for under £350 , a DS3/E3 router for under £2,000 , and an OC3/STM1 router for under £3,500, it will be difficult to turn the clock back to the days when customers were satisfied spending £1,000 on a T1/E1 router, £8,000 thousand on a DS3/E3 router, or £15,000 thousand on an OC3 router. But you don't have to turn the clock back to see prices like this, because these are the prices that Cisco still asks its customers to pay.

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