Enter Caw Networks. The company's first product -- Web-Avalanche -- is a load-generating powerhouse capable of pumping out more than 10,000 TCP connections per second. Now Caw has released WebReflector, a companion to Web-Avalanche. WebReflector can simulate as many as 100 Web servers, all with individual IP addresses, and, like its client-simulating sibling, can handle upward of 10,000 TCP connections per second.
Not only does this bad boy perform well, it also provides extensive reporting of TCP and HTTP statistics. Powered by dual GHz CPUs and 2 GB of RAM, WebReflector's custom-built operating system is fast, efficient and ready to replace all those servers you have sitting in your testing lab. The 4U-form-factor device is offered in two models: a four-port Fast Ethernet box or a single Gigabit Ethernet (fiber) interface model.
The device takes a long time to boot -- between two and three minutes -- but there's a good reason for this: The custom operating system uses QNX Software Systems' eponymous operating system as a bootstrap to load the operating system from the flash card to the hard drive every time the system boots. This design makes it nearly impossible to corrupt the system, and upgrades are a snap -- just get a new flash card.
I tested the first release of the gigabit-capable WebReflector in our labs in Green Bay, Wis., in conjunction with WebAvalanche and found that, together, the devices can easily form the basis of a thorough test bed for content switches, Web sites, firewalls and load-balancers.
Of Tests and Transactions
On either end of the lab I set up a WebReflector and a WebAvalanche, connected via Gigabit Ethernet interfaces on Cisco Systems Catalyst 6500 and Extreme Networks Summit 7i switches. WebReflector has a separate 10/100 Fast Ethernet link for administration. Once I gave WebReflector an IP address on the network, I was able to use the browser-based interface to configure the device, set up and run tests, and shut down or reboot the machine. Although it is possible to examine the inner workings of WebReflector by connecting a keyboard and monitor, there is an interface for managing the device from the command line, and all configuration and management tasks can be accomplished via the browser.
There are two conceptual parts to running a test on the WebReflector: a "test" and a "transaction." A test is the definition of a pool of servers, which can be queried and interacted with as though they were hardware servers. A server, aside from being assigned its own IP address, is also offered TCP parameters that control the timing and number of TCP retransmits. Because WebReflector runs on a custom TCP/IP stack, you can specify the time to wait between retransmits. You also can designate the maximum number of retransmits that will be allowed before the connection is considered defunct. A transaction comprises the HTTP headers, which can be fully customized; the status code; the type of data -- binary or ASCII; MIME type; and the size of the data to be returned when a request is received.
WebReflector does not serve up pages you create. Instead, it delivers a blob of data that is the size specified by the transaction. For example, I set up a transaction to return 1,000 bytes with a MIME type of text/html. Regardless of the request I sent to the WebReflector -- http://10.1.1.11/no-no.jpg or http://10.1.1.11/doesnotexist.html -- 1,000 bytes are returned with the status code specified.
One of the coolest aspects of this feature is that the size of the file returned can be completely randomized or customized in the URL. By specifying a mean size and a standard deviation in the transaction configuration, you can have WebReflector quickly calculate, create and return a page of the new size for each request it receives. Tack on "?Body-bytes=" to the end of a request, and you can specify the size of the file for WebReflector to return dynamically.
Another feature for server definitions is the introduction of latency. As with file size, latency can be defined as a mean with a standard deviation, or it can be specified as a concrete value. The latency feature forces the server to wait for the specified time before returning a response, effectively simulating a machine under heavy load or a less powerful system.
Servers, Servers, Data, Data
With the ability to simulate as many as 100 Web servers, a single WebReflector can easily replace most of your server-testing hardware. Using WebAvalanche, I generated a maximum load by creating 30,000 new TCP sessions per second. WebReflector kept pace without missing a bit, handling a sustained rate of 12,500 concurrent sessions per second. I was also able to beat on WebReflector using RadView Software's WebLoad to generate requests. The beast responded like a champ again, spitting out responses at a fine clip.
After the test finished, I examined the results. Statistical data, provided in an Excel spreadsheet, was so granular it made my teeth itch! From the number of syns, sy-nacks and fins to average data throughput and retransmits, WebReflector provided a wealth of information about not only the data and responses but the entire TCP/IP stack as well.
Missteps
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Vendor Information
WebReflector starts at $24,500.
Available: Now. Caw Networks, (650) 961-7000; (650) 961-2769. www.caw.com
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A few things in WebReflector need to be improved. Right now, a test is tied to a transaction; it would be great to be able to tie specific transactions to servers. Caw Networks says it is working on adding this capability to a future release.
The other issue I had is with the performance data. Only one set of performance statistics is stored per test. If you run a test and then run it again, the results from the first run are overwritten, so be careful to copy data from each test before running another.
WebReflector -- especially when coupled with its sibling, WebAvalanche, or another load-generating application such as WebLoad -- is a fine piece of hardware that anyone serious about performance testing should consider buying. WebReflector's price is reasonable when compared with the cost of the myriad servers that would be required to perform at the same level, and the reduced price of maintenance and operating system upgrades is certain to make even the CFO happy. Oh, one more thing: WebReflector has the coolest, brightest blue and orange lights I've seen in a while. What more could you possibly ask for?
Network Computing technology editor Lori MacVittie has been a software developer and a network administrator. Most recently, she was a member of the technical architecture team for a global transportation organization. Send your comments on this article to her at lmacvittie@nwc.com.
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