Jason Dixon wrote:
I have a Verizon USB720 dongle that shows up as ucom0. I intend to use
it for connecting remotely with my X40. I'm having problems when
packets exceed a certain size. When this happens, the return packets
never make it back to my system.
I can connect fine with ppp(8). I can ping remote hosts and do
traceroutes. I can ssh to hosts and perform basic commands. Only when
the payload exceeds ~900 bytes do things start to fail. This happens
with almost all TCP traffic, but is most noticeable with SSH or HTTP.
Many experience problem with the send/received window of the tcp packets
and can only get decent transfer speed when increase form the default to
65k.
# sysctl | grep space
net.inet.tcp.recvspace=16384
net.inet.tcp.sendspace=16384
net.inet.udp.recvspace=41600
net.inet.udp.sendspace=9216
try using it at 65536.
sysctl net.inet.tcp.recvspace=65536
sysctl net.inet.tcp.sendspace=65536
It may help you some, but if not, it's never the less real quick to test
and see if in your case it would help or not.
It may not help your MTU size limitation, but it sure should help your
performance however.
I hope it does help you never the less. On Windows laptop, if you don't
change the registry to use wider "TCP Receive Window" you loose lots of
performance. It's the experience of many users of the Verizon wireless
dongle anyway.
Best,
Daniel
