I’ve got a great tcp question.
There is a Windows ras server dialling to a number of remote QNX boxes. The
link is via radio. The radios are designed for nasty environments and
changing propagation conditions, when a link is established it stays
established. However they are half duplex and NB they switch between tx and
rx once per second! Yes even though the bit rate is 2400, for 1 second you
receive and then for 1 second you transmit. For tcpip this is a packet per
second throughput or packet and ack in under 2 seconds.
For the simple protocol that they used in the past, this was ok. Now they
want to use tcpip. We have setup the Windows and QNX sides to work perfectly
with normal modems, however when we replace the modems with the radios no
joy. It nearly works, the link is established and ip addresses are assigned
at both ends, its just that the very last part of the arbitration isn’t
completed and the QNX box keeps attempting to reset the QNX boxes default
So my question is, is there a way to adjust the timings in the tcp stack so
that a link this slow will work?
I have noted a tcp_nodelay parameter for sockets that tries to send as many
packets at once, but this seems to apply only to a socket. I need to do this
for the whole stack.
PS yes we are asking the manufacturer if the switching can be done more
quickly. No answer as yet.