ArrowPoint, meanwhile, focuses on intelligence at the expense of speed. There is no Gigabit uplink in the CS-100 and the device has a separate shared control plane, to which Web switching decisions are referred. Neither of the products tested supported HTTP 1.1, an enhancement to the Web's protocol which allows persistent connections. However, for DNS round-robin scheduling, a list of IP addresses is defined for the named server and given to the DNS server. As each request comes in, it receives the next IP address on the list.
Load balancers offer greater control of the redirection process.
They can detect when a server is not responding and take it off the list, where DNS round-robin would go on sending requests to that server. With Layer 4 switching, the Web switch can determine, by port number, what protocol is being used. It also sets up network address translation, so several real servers appear to be one large virtual server. Layer 7 switching looks even further into the packets. It identifies specific URLs and file names, so content can be divided onto separate servers.