How should I determine the number of frame buffers to configure (NBUFFS)?
This is an important consideration, since frame buffers make up the bulk of the smxNS memory requirements. As a rule of thumb, we recommend 5 frame buffers per active TCP connection. This should yield good performance for applications that transfer bulk data over TCP, but it may be overkill in other cases. If some connections might be idle, or more sporadic in data transfer, then you could get equivalent performance with fewer frame buffers. One more complicating issue with frame buffers is that many Ethernet controllers are designed to use pre-allocated buffers that receive incoming frames. These buffers would be in addition to the rule of thumb “5 per connection”. Recent releases of smxNS include a variable to track the “low water” point of the the frame buffer pool, so you could stress your system and then check this value to see how much headroom you have in the setting of NBUFFS. This value can even be accessed through a Telnet session to the device, or using the optional smxAware
