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Content Smart Web Switch

A Web switch from ArrowPoint Communications, Inc., Westford, MA, that routes traffic based on the URL of the request and an extensive database of rules. Using an ATM switch as its foundation, it analyzes the HTTP request and sets up a flow through the switch to the appropriate output port for the remainder of that HTTP session. After receiving the TCP connection request from the browser, it spoofs the client to obtain the HTTP header which contains the URL of the request so that the switch can route it to the most efficient server. The switch can also implement an additional quality of service (QoS) layer by writing a cookie onto the client's machine that is resubmitted with each HTTP request. In 2000, Cisco acquired Arrowpoint to provide its customers with a robust and flexible switching platform. See Web switch.

Content Smart Switches
ArrowPoint Communications pioneered Web switching with the CS-100 switch on the left, which supports up to 16 Fast Ethernet ports. The CS-800 (right) supports up to 32 Gigabit Ethernet ports.

Web switch

A network device that routes traffic to the appropriate Web server based on the content of the packet. Also known as a "URL switch," "Web content switch," "content switch," "layer 7 switch" and "layer 4-7 switch," the Web switch is designed to provide improved load balancing for a website, because different requests can be routed to the servers configured to handle them.

For example, streaming audio and video have long-lived "sticky" connections and may be better served from a dedicated server or one that is closer to the user. Requests for static data can be directed to cache servers, while dynamic requests bypass the cache server.

Layer 7 Digs Deeper
The Web switch examines layer 4 and layer 7 in the network packet. Although any layer 4 switch can examine the TCP/IP port number and differentiate HTTP traffic (Web traffic) from the rest, the Web switch also inspects layer 7, which contains the details of the HTTP request. For example, an HTTP request for a static image would be directed to a cache server, while an HTTP request for a search would go to the Web server handling ad hoc queries. See well-known port, Content Smart Web Switch and TCP splicing.


  Layer and      Forwarding
  Protocol       Decision
  Inspected      Based on

  2 - Ethernet   MAC address

  3 - IP         Network address
  3 - IP         Service quality

  4 - TCP/UDP    Traffic type
      socket     (HTTP, FTP, etc.)

  7 - HTTP       HTTP request type

The First Web Switches
ArrowPoint Communications pioneered Web switching in 1998 with its Content Smart switch. The CS-100 (left) supported 16 Fast Ethernet ports, while the CS-800 (right) supported 32 Gigabit Ethernet ports. (Image courtesy of Cisco Systems, Inc.)

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