ch20: Redirections and Load Balancing

20.重定向与负载均衡

1. Why Redirect?

• Perform HTTP transactions reliably

• Minimize delay

• Conserve network bandwidth

2. Overview of Redirection Protocols

General redirection methods:

• HTTP redirection

• DNS redirection

• Anycast addressing

• IP MAC forwarding

• IP address forwarding

Proxy and cache redirection techniques:

• Explicit browser configuration

• Proxy auto-configuration (PAC)

• Web Proxy Autodiscovery Protocol (WPAD)

• Internet Cache Protocol (ICP)

• Cache Array Routing Protocol (CARP)

• Hyper Text Caching Protocol (HTCP)

3. General Redirection Methods

3.1 HTTP Redirection

Response:

HTTP/1.0 302 Redirect
Server: Stronghold/2.4.2 Apache/1.3.6
Location: http://161.58.228.45/hammers.html

3.2 DNS Redirection

Just like zkname.

4. Proxy Redirection Methods

4.2 Explicit Browser Configuration

Most browsers can be configured to contact a proxy server for content.

4.3 Proxy Auto-configuration

An automatic configuration methodology that allows browsers to dynamically configure themselves to contact the correct proxy server solves this problem.

4.4 Web Proxy Autodiscovery Protocol

PAC file autodiscovery.