Nortel Networks WEB OS 212777 - Manual (Page 304)

Web OS 10.0 Application Guide
304 n Chapter 12: Global Server Load Balancing
212777-A, February 2002
IP Proxy for Non-HTTP Redirects
Typically, client requests for HTTP applications are automatically redirected to the location
with the best response and least load for the requested content. This is because the HTTP proto-
col has a built-in redirection function that allows requests to be redirected to an alternate site.
If a client requests a non-HTTP application such as FTP, POP3, or SMTP, then the lack of a
redirection function in these applications requires that a proxy IP address be configured on the
client port. The client port will initiate a redirect only if resources are unavailable at the first site.
N OTE – This feature should be used as a method of last resort for GSLB implementations in
topologies where the remote servers are usually virtual server IP addresses in other Alteon
Web switches.
Figure 12-3 illustrates the packet-flow of HTTP and non-HTTP redirects in a GSLB environ-
ment.
Figure 12-3 HTTP and Non-HTTP Redirects
Client Site
DNS
Request
Site 1
DNS
Web
Servers Web
Servers
DNS
Web Switch Web Switch
Site 2
HTTP Applications
Non HTTP Applications
Proxy IP address is
configured on Client
port for non-HTTP
applications.
DNS
Internet
1a
1b
2a
2b