Alteon Application Switch Operating System Application Guide
Application Redirection
Document ID: RDWR-ALOS-V2900_AG1302
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Adding Alteon with optional Layer 4 software addresses the following issues:
•
Cache servers can be added or removed dynamically without interrupting services.
•
Performance is improved by balancing the cached request load across multiple servers. More
servers can be added at any time to increase processing power.
•
The proxy is transparent to the client.
•
Frames that are not associated with HTTP requests are normally passed to the router.
Additional Application Redirection Options
Application redirection can be used in combination with other Layer 4 options, such as load-
balancing metrics, health checks, real server group backups, and more. For more details, see
Implementing Server Load Balancing, page 167
.
Cache Redirection Example
The following is an example cache redirection configuration.
Example
Cache Redirection Configuration
The following is required prior to configuration:
•
You must connect to the CLI as the administrator.
•
Layer 4 (SLB) software must be enabled.
Note:
For details about these procedures or any of the menu commands described in this example,
see the Alteon Application Switch Operating System Command Reference.
In this example, Alteon is placed between the clients and the border gateway to the Internet. Alteon
is configured to intercept all Internet bound HTTP requests (on default TCP port 80), and redirect
them to the cache servers. Alteon distributes HTTP requests equally to the cache servers based on
the destination IP address of the requests. If the cache servers do not have the requested
information, then the cache servers behave like the client and forward the request out to the
Internet.
Note:
Filters are not limited to the few protocols and TCP or UDP applications shown in this
example. See
Well-Known Application Ports, page 175
for a list of well-known applications ports.
1. Assign an IP address to each of the cache servers.
Similar to SLB, the cache real servers are assigned an IP address and placed into a real server
group. The real servers must be in the same VLAN and must have an IP route to Alteon that will
perform the cache redirection. In addition, the path from Alteon to the real servers must not
contain a router. The router would stop HTTP requests from reaching the cache servers and
instead direct them back out to the Internet.
More complex network topologies can be used if configuring IP proxy addresses (see
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