Equalizer Balances Web Site Traffic

If the above scenario becomes a reality, the typical solution is to add more servers to the network and distribute the incoming requests across all servers. But if the requests are distributed randomly, an already overburdened server could receive even more requests, swamping it further still. Users trying to connect to the server might then receive the dreaded "server down" message.




Technical Editor

Coyote Point Systems has a solution. The Equalizer E450 is a 1U rack-mount Layer 7 load-balancing switch that selects servers according to user-defined load-balancing criteria. It takes just milliseconds for the Equalizer to route requests to the least- loaded server. Users just see one fast server while the Equalizer works quietly in the background. The Equalizer automatically detects server failures and routes requests to other servers as needed.

For full redundancy, a backup Equalizer can be configured along with the primary unit, which will preserve all established connections if the first unit fails. Useful not only for balancing Web sites, the Equalizer can also add scalability and availability to e-mail, news, SSL or almost any other TCP/IP-based service.

The Equalizer features a TCP/IP address translation engine that can handle more than 130,000 HTTP GET operations per minute. It does not require any server software or operating system modifications and is compatible with Unix, Linux, Windows and Macintosh operating systems. The Equalizer's Web-based interface makes administration tasks easy, although command-line administration is also supported, including Secure Shell command-line access. The Equalizer supports an unlimited number of virtual clusters with 64 servers per cluster and up to 4 million simultaneous active connections. Servers can be added and removed without interrupting user service.

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Coyote Point's Layer 7 load-balancing capability lets administrators specify the rules for directing client traffic to create the most flexible cluster configurations possible. This allows such things as having all requests for graphics files be directed to servers that can best handle graphics while sending all requests for Perl scripts to the most appropriate servers, and then having all other requests go to yet another server.

The Equalizer enables load-balancing decisions to be made based on HTTP protocol version, host name, path name, file name, pattern matches against arbitrary HTTP request headers and so on. The unit's Layer 7 HTTPS support also permits load balancing based on the SSL protocol level.

The load-balancing algorithms can be configured to consider server response time, active sessions, direct server measurements, server weighting and observed latency when routing traffic.

Setting up the Equalizer is easy. Servers are connected to the unit through a switch to the Equalizer's internal network interface, while the outside world connects via a second switch to the Equalizer's external network interface. Servers should be configured with unique addresses on the internal network, and they should use the Equalizer's internal address as the default gateway. The Equalizer's serial port can be connected to a terminal or terminal emulator using a supplied nine-pin serial cable. When the Equalizer finishes booting, the administrator should log on and verify the internal and external network addresses and netmasks. At this point, custom load-balancing policies can be implemented.

Once the Equalizer is set up and load-balancing algorithms are properly configured, it's pretty much a hands-off appliance that will require little or no attention from an administrator. But new rules can easily be implemented at any time, should the need arise.

Administrators of busy Web sites will love what the Equalizer can do for them and how easy it is to use. The product is ideal for Web sites that occasionally see traffic spikes that wreak havoc on an otherwise-reliable service.

PRICE: $9,995
MARGIN: 25 percent
WARRANTY: 1 year


CHANNEL OVERVIEW: Coyote Point Systems has sold almost exclusively through solution providers for five years, but the San Jose, Calif.-based company recently signed its first distributor and is developing a channel program. The program includes collateral materials, along with limited technical training and integration assistance, both via telephone. An authorization and training program is planned.

Note: Vendors can earn up to five stars for technical merit and five for their channel program. If the average of these two scores is four stars or greater, the product earns CRN Test Center Recommended status.