We are using QNX 6.5.0 base install (not SR1).  We can configure our products in a leader/follower (master/slave has 
been declared politically incorrect) setup where multiple units are interconnected and communicate to each other via TCP
.  We normally experience an acceptable up to 300 ms command/response times with this setup.  However, we occasionally 
lose a packet from one of the followers.  When this happens, there is a 1.5 second or longer delay before TCP 
retransmits.  I have confirmed the packet loss by simultaneously monitoring the internal traffic using tcpdump and the 
output traffic with Wireshark.  The actual packet loss seems to be an incompatibility between the card we are using and 
our internal switch.  I am working with our vendor to find a solution.

I have a question about io-pkt-v4, which we are using.  RFC2581, TCP Congestion Control, Secion 3.2 describes TCP Fast 
Retransmissions, which should alleviate this problem.  I'm guessing that io-pkt-v4 does not support this RFC.  We have 
avoided upgrading to SR1 due to the amount of regression testing of our product with such a change.  Is RFC2581 
supported in later releases of io-pkt-v4?