Cisco Cisco Web Security Appliance S380 User Guide

What are these parameters?

The WSA has several buffers and optimization algorithms which can be altered for specific needs. 
Buffer sizes are originally optimized to suit the “most common” deployment scenarios. However, 
larger buffer sizes can be used when faster per-connection performance is needed, but note that 
overall memory usage will increase. Therefore, buffer-size increases should be in line with the 
memory available on the system. The send- and receive-space variables control the size of the 
buffers available for storing data for communication over a socket. The send- and receive-auto 
options are used to enable and disable dynamic scaling of send and receive TCP window sizes. 
(These parameters are applied in the FreeBSD kernel.)

How were these example values determined?

We tested different sets of values on a customer’s network where this “problem” was observed, and 
“zeroed in” on these values. We then further tested these changes for stability and performance 
increase in our labs. You are free to use values other than these at your own risk. 

Why are these values not the defaults?

As mentioned, by default the WSA is optimized for the most-common deployments, and operating 
in a very large number of locations without per-connection performance complaints. Making the 
changes discussed here will not increase RPS numbers, and in fact may cause them to drop. 

Important! If you need to cycle power to your x80 oappliance, wait at least 20 minutes for the appliance 
to come up again (all LEDs are green) before pushing the power button. 

Lights on the front and/or rear panels of your hardware appliance indicate health and status of your 
appliance. For descriptions of these indicators, see the hardware guides available from 

Specifications for your appliance, such as temperature ranges, are also available in these documents.