Sharing the load

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Both click-and-mortar and dot-com companies are quickly learning that in the e-business world, Web performance is everything. With the stakes for loss of revenue or business failure higher than ever, companies of every ilk are looking for Internet technology solutions that not only optimize the network infrastructure but provide end-users with the peak experience they demand, as well. To the rescue: load balancers. In this article, we’ll examine how load balancers are increasing site availability and eliminating the risks associated with downtime.

Managing the traffic load

Technology on the rise

In a recently issued report on Layer 4/7 server load balancing switch and appliance market from the Dell’Oro Group, a market-research company that focuses on networking technology based in Portola Valley, Calif., the market is expected to double to in excess of $500 million in 2000. Figure 1 shows the market leaders at the beginning of 2000. Figure 2 shows the projected market.

Load balancers are now a check-list item for many companies doing business on the Internet. Also known as Internet traffic management devices, load balancers sit at the center of a variety of network devices and are designed to improve performance, availability, and reliability. Simply stated, a load balancer’s basic role is to balance the workload for a group of servers, or to throttle traffic, to the best server location, and, thus, increase the servers’ overall efficiency. Load balancers distribute server requests in such as way that some servers do not sit idle while other servers are overworked.

Let’s look at a real-life example. Four-year old Ticketmaster Online-City Search (a company that builds large-scale content and transaction sites on the Internet) hosts over 1,000 domains in 77 local markets–which recently added up to 210 million page views in a single month. As the domcom enterprise grew over the past several years, it quickly recognized that it needed to add load-balancing devices to its network infrastructure.

We’re ramping up traffic and I want 100 percent uptime, the ability to scale to greater numbers of domains and the ability to scale applications, says Will Layton, vice president of Internet and information services at Ticketmaster Online-City Search, of Pasadena, Calif.

He got it. For a cost of about $14,000 per load-balancing device, or $252,000 for 18 load-balancing switches, from Alteon WebSystems Inc., of San Jose, Calif., Ticketmaster believes it is able to better serve its customers. Our site is world-class fast which keeps the customer at the site and keeps them there longer, he says. The bottom line for the business: more customers, more sales transactions.

At a time when industry research indicates that it takes just eight seconds to lose an e-commerce customer if a Web site isn’t responding, Ticketmaster wasn’t about to take chances. The company set its sights on a response time of two seconds with the help of load-balancing technology.

Click to view Figure 1

Click to view Figure 2

Tuning Web performance

Whether a company has two Web servers or twenty, customers visiting a company’s Web site expect to get access to information in a reasonable amount of time. For the enterprise, these expectations translate into meeting a challenge that is twofold: providing the end user with a good experience (i.e. good server availability, performance and reliability) and being able to do so in a cost effective manner.

Just a few years ago, only companies that had a minimum of five Web servers were interested in load balancing. However, today, that’s changed because their focus has changed, from scalability to availability, says Bill Kish, chief technology officer at Coyote Point Systems Inc., Santa Clara, Calif.

The truth of the matter is that Web customers are much less forgiving than internal network users, thanks to what they’ve come to expect of the Internet–namely, immediacy. In fact, Web customers aren’t very different than customers doing business in a walled facility–they’ll leave if they don’t get the information they want or if the sales staff is slow or unavailable. The same thing happens on the Internet, but the rate of departure boils down to a matter of seconds. While the realm of the customer experience has changed, one thing has remained the same: service is everything.

Given that fact, e-businesses don’t look at sales people, they look at servers:

  • Are they capable of meeting traffic demands?
  • Are they available when called on?
  • Are they reliable?

We needed to create a network infrastructure that could handle traffic spikes, provide users with a good experience and fit into a constrained budged, says Allen Murabayashi, vice president of engineering at New York-based

The Internet recruiting solutions company runs two tiers of servers: a bank of Web servers and a bank of database servers adding up to more than 50 devices in all. After scanning the market place for load balancing solutions it turned to Foundry Networks, San Jose, Calif.

The vendor offers the ServerIron family of Internet Traffic Management Switches based on OSI Layer 2 through OSI Layer 7 definitions. According to Chandra Kopparapu, product marketing manager at Foundry, product prices begin at $7,995 for an 8-port device and climb up to $150,000 to $200,000 for a 168 port switch. purchased a total of six ServerIron products, ranging in price from $8,000 to $15,000. Like many companies, the dotcom company configures the load balancing switches in pairs, thereby creating two side-by-side with failover. Two ServerIron XL devices frontline the company’s Web servers; two ServerIron devices frontline the job database servers; and another pair of switches are used for the resume database servers. The load balancing product we chose doesn’t offer a lot of sophisticated features but it offers us a lot of parameters for load balancing and gives us a good indication as to what’s going on with our machines, says Murabayashi.

Closer look

Optimizing Web infrastructure costs

E-business is forcing companies to make new investments in the network infrastructure. When it comes to load balancers, the good news is that costs can be contained. That’s because load balancing devices deliver both robust availability and affordable scalability, thereby mitigating the impact of a single server’s failure and allowing managers to roll out more, slightly slower, servers at great savings, according to Montreal-based Networkshop Inc.

Load balancing devices make it affordable to deploy processing capability by reducing the cost for a given amount of processor capacity, says Alistair Croll, cofounder of Networkshop.

For example, while a Pentium 600Mhz machine may cost $2,000 to $3,000, a four processor, or quad-machine may run $30,000, and an 8-way processor machine may cost $80,000. Using a single, larger Web server is not only more expensive but can lead to a single point of failure and require additional upgrades as additional processing power is required.

In contrast, by using, say, four lower powered machines, a company can spend approximately $8,000 to $12,000–thus saving money and guaranteeing that if one machine fails, three are still running. To the outside world, a load balancer makes a cluster of four servers appear as one, and provides reliability and availability. The load balancer also optimizes how Web traffic is managed by optimizing the performance of each device and enhancing the end users experience.

It’s important to note that there’s a substantial cost difference between OSI Layer 4 load balancing devices and a smarter OSI Layer 7 product. Product prices range from $5,000 for the former up to $35,000 for the latter. And, purchases are commonly made in pairs for failover.

When you’re thinking about costs, don’t forget about vendor maintenance, which runs the usual 10% to 15% of product cost. Support service costs vary among vendors depending upon the level of support contracted for (i.e., 8hr/5day versus 24×7).

If you scan the load balancing product market, what becomes apparent is the variety of available solutions from multiple vendors. For example, you’ll find load balancer appliances, software-based load balancers, and switched-based load balancers.

Here’s what each device type offers:

  • Load balancer appliances–This is the more traditional product offering. These devices are often souped-up PCs with software specialized to load balance. They tend to be Intel-based and come with a general-purpose operating system, such as Unix.
  • Software-based load balancers–In this product flavor, the vendor offers a software solution that must be installed on every server, i.e. a PC or workstation, which requires installation and configuration.
  • Switch-based load balancers–These devices appear to be increasing in popularity and continue to evolve technically. The early switch-based load balancer was a traditional network switch with software written for the switch to give it load balancing functionality. Switches come in two flavors:
    • Switches with multiple ports, multiple inputs, a specialized operating system, and specialized chips for OSI Layer 2 and 3 switching–These devices included specialized chips for fast packet forwarding and provide increased speed and resiliency. If one port goes down, other ports can take over. Vendors ported load balancing code to the switch.
    • Web switches–Over the past 12 to 18 months, the industry has seen the emergence of Web switches. This device is a network switch with specialized chips put on every port for packet forwarding and session processing. These are multifunction devices that go beyond load balancing only and offer other traffic management capabilities such as bandwidth management, security, packet-filtering and routing and switching.

Which load balancing type is right for any organization depends a number of factors–for example, who makes purchasing decisions, pricing considerations and in-house skills. For example, appliance type load balancing devices are popular with network managers because they’re delivered as a turnkey solution. What this means is that the product is pretested for hardware/software compatibility before it goes out the door. By the time it reaches the customer’s door there’s no muss, no fuss for the network manager. Product performance is also said to be reliable. However, like any piece of hardware, there’s a good chance that the boxes, however many are purchased, will require an upgrade sooner or later.

Vendors report that according to their observations, network people lean toward appliances while software types like software-based solutions. For companies with the technical expertise to install and configure software-based load balancing solutions, this product option allows solutions to be optimized and adapted to a particular environment. However, companies lacking the appropriate skill set may find this type of solution too time consuming or expensive to maintain, especially if the expertise must be acquired on a contract basis.

Web switches, or multifunction devices, are hailed by proponents for their ability to do both switching and load balancing functions in a single box, thereby minimizing the number of separate network devices an organization must purchase. These switches reportedly offer better throughput than either the load balancing appliance or the software solution. Naysayers, however, point out that no single-solution box can be fast enough or capable enough to do everything, and that multifunction devices are more difficult to troubleshoot.

Keep intelligence in mind

Whatever flavor of load balancing product a company considers, industry watchers advise to consider this: intelligence. According to market research, intelligent solutions are hot in the load balancing market space. This higher functionality not only enables these devices to look at OSI Layers 2/3 but 4/7, as well. Smart devices have the ability to look at the data portion, or content portion–URLs, cookies and other identifiers–of Web traffic and route traffic to the appropriate servers. Devices with extended intelligence can also do extended health checks of both servers and applications.

Distributed load balancing

Load balancing has become more sophisticated in more ways than one with the ability to do distributed load balancing. Early products did one location load balancing. Today, companies can do distributed load balancing, says Long.

According to the Internet Research Group, a research and consulting firm in Los Altos, Calif., there are two types of Internet traffic management products:

  • Traffic manager–Sits between the Internet and the cluster of servers that collectively constitute a Web site. The traffic manager receives the requests directed to the site and sends each request to one of several servers.
  • Traffic distributor–Offers the same advantages for multiple Web sites that the traffic manager does for servers within a Web site. A traffic distributor operates through the Domain Name Server (DNS) functions of the Internet and directs a browser’s request to the most appropriate Web site when a Web site owner has identical sites in several geographic locations.

Ticketmaster’s Layton, a network-oriented person, chose Alteon’s ACEdirector Web switch rather than a software solution or turnkey appliance. Being hardware-based was a big plus for the switch product because it tends to be more reliable than software and easier to manage, he says. The vendor’s product offers intelligent Layer 2 through Layer 7 switching, as well, which optimizes the load balancing function both locally and globally at Ticketmaster. The dotcom company has four data centers, two in Los Angeles, one in Chicago and one in Dallas.

The bottom line to load balancing is that it’s all about high availability and eliminating risk if a site goes down or if a server is overloaded. Organizations whose revenue relies, in part, on its Web site performance, are making load balancing a part of the network infrastructure.Our goal is to continuously improve the customer experience, says Layton.

Cross Links–linked from vendor ranking list, except for Coyote Point System

Vendor links:

**ArrowPoint Communications was recently acquired by Cisco Systems Inc.


Lynn Haber writes on business and information technology from Norwell, Ma.

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