I just discovered something that MIGHT help someone find the problem.
If I FTP the file first to a Sun Pizza-box, then I FTP through my
Linux ppp server, it works fine! There are NO long waits. However,
If I FTP FROM a Linux box TO a Linux box I have that problem. If
I FTP FROM a Linux box to a Sun I have no problem even if a Linux
box is routing packets. If I FTP FROM a Sun to a Linux box I have
no problems, even with an intermediate Linux box routing.
The long-wait ONLY occurs if there is a Linux Box on both ends!
Maybe duplicate packets are not being ACKed right away? If these
ACKs are deferred, there might be problems filling holes?
Now, looking at a 'tcpdump' of the packets shows that the Sun ACKs
every packet immediately if it is receiving data, i.e., I get alternate
packets from Linux->Sun, Sun->Linux repeatedly, every other packet
is an ACK. The same is true for data in the other direction. Now, when
I go between linux boxes, I get large volumes of data packets with only
an occasional ACK (which is what we really want to reduce overhead).
There is no problem on a faster link like Ethernet or our Internet
connection. This problem only occurs using a 28.8 kb link. Is it possible
that needed buffers are being expired by TIME so that an ACK with a
long-time-ago sequence number confuses the buffering?
If anyone is working on this problem, I can readily test a patch.
Cheers,
Dick Johnson
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Richard B. Johnson
Project Engineer
Analogic Corporation
Voice : (508) 977-3000 ext. 3754
Fax : (508) 532-6097
Modem : (508) 977-6870
Ftp : ftp@boneserver.analogic.com
Email : rjohnson@analogic.com, johnson@analogic.com
Penguin : Linux version 2.1.29 on an i586 machine (66.15 BogoMips).
Warning : I read unsolicited mail for $350.00 per hour. Supply billing address.
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-