Snort performance concerns

[Larry Wichman <larrywichman () yahoo com>]

I enabled Performance Monitor on my sensors and I have some concerns after looking at some of the performance stats. 
First, I have three sensors, two of which average 96mb/sec of traffic and the dropped packets percentage average is 
about 10% (proc and memory utilization are high, as expected). I have a third sensor that sees an average of about 
5mb/sec and has the same amount of dropped packets, memory and proc utilization are minimal. I have implemented all the 
suggested optimizations (I think), patched Libpcap, etc….I can understand that there would be some dropped packets when 
the traffic is at a high, continuous load, but the third sensor with the same amount of dropped packets with only a 
fraction of the traffic  concerns me.  I am thinking about upgrading the hardware (faster proc, bus speeds, etc…), but 
I might be wasting money if the stats are the same.  Does anyone have any input as to what is causing the dropped 
packets? 

Also, my boss told me to start evaluating commercial products. My first choice would be Sourcfire, I really do like 
working with Snort, but I need whatever product I choose to be able to handle the amount of traffic that we have. I 
would greatly appreciate any input on this. Cheers.

 

Larry