Transparent proxying requirements for an L4 or L7 switch

About using a switch for transparent proxying

You can use an L4 or L7 switch to pass DNS, FTP, HTTP, NNTP, MMS, and RTSP requests to the appliances. To learn more about the differences between L4 and L7 switches, see the Deployment Guide.

L4 and L7 switch deployment requirements

To deploy appliances with an L4 or L7 switch, you need to

Place the switch in an optimal network location
For more information, see Switch location recommendations.
Configure the switch so that it can pass requests to the appliance
See the switch vendor's documentation and Choosing an L4 or L7 switch request distribution method.
Configure transparent proxying options in the Appliance Manager (or CLI) for the protocols you want to redirect
For configuration procedures, see the Appliance Manager online Help.

Requirements for transparent proxying with a switch

To deploy transparent proxying with an L4 or L7 switch, you must meet the requirements listed in the following table. Network Appliance also recommends that you comply with the "best practice" recommendations that are listed in the table. Items listed in the table are requirements unless otherwise noted.

Category	Requirements and recommendations
Appliance	A network interface is required for each switch attached. The appliance should be directly connected to the switch (best practice).
Network layout	The switch must be in a location to detect all traffic for the clients it is expected to serve.
L4 or L7 switch configuration	Switch configuration involves the following high-level steps: Identify traffic to be redirected to the appliances and the request distribution method to be used. Identify the appliances to which traffic is to be redirected. Contact your switch vendor for specific switch configuration settings.
NetCache configuration	For each protocol for which you want to set up transparent proxying, enable the transparency feature. See the Appliance Manager online Help for configuration details.

Switch location recommendations

The following table provides recommendations for locating your switch.

Switch location in relation to...	Comments
Appliances	L4 and L7 switches use MAC address rewriting as the method for redirecting packets. Therefore, your L4 and L7 switches must be on the same subnet as the appliances to which the switch is to redirect packets. For maximum efficiency, Network Appliance recommends directly connecting the switch to each appliance.
Clients	The switch must be located so that it can view all network traffic for the clients that it is expected to serve.

Switch location in relation to...

Comments

Appliances

L4 and L7 switches use MAC address rewriting as the method for redirecting packets. Therefore, your L4 and L7 switches must be on the same subnet as the appliances to which the switch is to redirect packets.

For maximum efficiency, Network Appliance recommends directly connecting the switch to each appliance.

Clients

The switch must be located so that it can view all network traffic for the clients that it is expected to serve.