2.0.30 pre-patch & TCP Stall

edgy (edgy@alliedtours.com)
Sun, 6 Apr 1997 01:43:36 -0500 (EDT)

I was interested in the TCP Stall thread that's still going around here
since I know I've experienced the same types of problems outlined in some
of the posts here when connecting to a Linux 2.0.29 SMP server using a
2.0.x box.

Several variables have changed since that situation, but the end result
seems to be that I'm not getting any more stalls. Here's a sample output
that I get from TCP dump from my machine now:

02:24:02.669083 208.193.190.4.ftp-data > 208.193.190.233.1098: . 948065331:948066791(1460) ack 241550100 win 31744 [tos 0x8]
02:24:02.679031 208.193.190.233.1098 > 208.193.190.4.ftp-data: . ack 1460 win 8192 [tos 0x8]
02:24:03.209030 208.193.190.4.ftp-data > 208.193.190.233.1098: . 1460:2920(1460) ack 1 win 31744 [tos 0x8]
02:24:03.218995 208.193.190.233.1098 > 208.193.190.4.ftp-data: . ack 2920 win 8192 [tos 0x8]
02:24:03.749024 208.193.190.4.ftp-data > 208.193.190.233.1098: P 2920:4380(1460) ack 1 win 31744 [tos 0x8]
02:24:03.758993 208.193.190.233.1098 > 208.193.190.4.ftp-data: . ack 4380 win 8192 [tos 0x8]
02:24:04.289024 208.193.190.4.ftp-data > 208.193.190.233.1098: . 4380:5840(1460) ack 1 win 31744 [tos 0x8]
02:24:04.299003 208.193.190.233.1098 > 208.193.190.4.ftp-data: . ack 5840 win 8192 [tos 0x8]
02:24:04.839028 208.193.190.4.ftp-data > 208.193.190.233.1098: . 5840:7300(1460) ack 1 win 31744 [tos 0x8]
02:24:04.848992 208.193.190.233.1098 > 208.193.190.4.ftp-data: . ack 7300 win 8192 [tos 0x8]

It all seems good now. After every packet, some sort of acknowledgement
is sent to the system, and files transfer in the proper amount of time.
The above was obtained at a 24000 bps connection.

At any rate, the current configuration is 2.1.29 on the machine I'm
connecting from.

The machine I'm connecting to is an SMP machine still, but has the kernel
compiled WITHOUT SMP support (seems more stable), and running one of the
pre-patch 2.0.30 (I believe the first one that came out), with all the
SYN flooding and RST cookies protection enabled.

I'm not sure why it's working properly now, but maybe someone else that
has the prepatch running should see if that makes a difference at all.
The only other factors really are that I'm running 2.1.29 on the home
machine, and no SMP anymore on the dialup server.

At any rate, I've thrown my two cents in at helping find out what was
causing the TCP stalls. I just hope I waited long enough to make sure it
wasn't happening anymore.

-Ben