Web switch
A network device that routes traffic to the appropriate Web server based on the URL of the request. Also known as a "URL switch," "Web content switch," "content switch" and "Layer 7 switch," the Web switch is designed to provide improved load balancing for a Web site because different requests can be routed to the most efficient source for delivering their content.
For example, streaming audio and video, which have long-lived "sticky" connections, might be better served from a dedicated server or from a server that is closer to the user. Search requests that have to be processed would specifically not be directed to a cache server, because the cache would only have to redirect it to the origin server.
Targeted Load Balancing
Web switches provide more targeted load balancing than layer 4 switches. Although layer 4 switches can examine the TCP/IP port number and differentiate HTTP from FTP and SMTP traffic, Web switches can differentiate HTTP requests and send them to the appropriate servers for processing. For example, requests for HTML pages are switched to one Web server while searches go to another, and streaming media requests go to yet another. ArrowPoint Communications (later acquired by Cisco) pioneered this technology in 1998. See Content Smart Web Switch and TCP splicing.
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| The First Web Switches |
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| ArrowPoint Communications pioneered Web switching in 1998 with its Content Smart switch. The CS-100 (left) supports up to 16 Fast Ethernet ports, while the CS-800 (right) supports up to 32 Gigabit Ethernet ports. (Image courtesy of Cisco Systems, Inc.) |