Technical data

Brocade ServerIron ADX Advanced Server Load Balancing Guide 39

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Sample deployment topologies

NOTE

For real servers that are in multiple subnets and are configured with source NAT IP addresses, the

netmask will be used by the ServerIron ADX to select the “best” source NAT IP address to use.

VIPs with reverse proxy

In the following example, SLB is configured and one or more of the virtual ports have reverse proxy

SLB enabled (cache-enable). This is usually the case with server side caching topologies, when the

cache server is running in transparent mode. This means that traffic destined to that particular VIP

will be redirected to the cache server. If the cache server does not have the requested data, it

makes a connection to the VIP, which is then load balanced across the real servers, and retrieves

the data.

NOTE

FTP is not supported for TCS with source NAT.

The previous diagram illustrates the packet flow in a TCS configuration with a VIP that has reverse

proxy SLB enabled. Flow 1 shows the client request getting forwarded to the cache server. If the

cache server has the required information, it is sent to the client via Flow 4. If the flows cache

server does not have the information, it accesses the VIP via Flow 2 and the traffic from the load

balanced real server to the cache server comes from Flow 3.

The following table lists the entries that need to be programmed in the CAM for hardware

forwarding of pass-through traffic.

TABLE 2 Required CAM programming for simple TCS with source NAT configuration

Level Match Hash

1 Source NAT IP address Destination port

2 Destination port Source IP address

Source port Destination IP address