Messages in this thread | | | Date | Fri, 2 Sep 2005 19:09:18 -0400 (EDT) | From | Ion Badulescu <> | Subject | Re: Possible BUG in IPv4 TCP window handling, all recent 2.4.x/2.6.x kernels |
| |
Hi Alexey,
On Sat, 3 Sep 2005, Alexey Kuznetsov wrote:
>> Well, take a look at the double acks for 84439343, 84440447 and 84441059, >> they seem pretty much identical to me. > > It is just a little tcpdump glitch. > > 19:34:54.532271 < 10.2.20.246.33060 > 65.171.224.182.8700: . 44:44(0) ack 84439343 win 24544 <nop,nop,timestamp 226080638 99717832> (DF) (ttl 64, id 60946) > 19:34:54.532432 < 10.2.20.246.33060 > 65.171.224.182.8700: . 44:44(0) ack 84439343 win 24544 <nop,nop,timestamp 226080638 99717832> (DF) (ttl 64, id 60946) > > It is one ACK (look at IP ID), shown twice. This happens sometimes > with our packet socket.
Ahh... ack. :) That explains it.
> I understood. I expect when 184*4, when you said 184. But minimum is > still 730 (unscaled 1460*2). If you really saw values lower than 730 > (unscaled 1460*2), there is another more severe problem and the suggested > patch will not solve it.
I really did see very small values. This one is plucked from one of today's streams, after a full day's worth of data had passed through it:
19:03:19.659454 10.1.12.11.8001 > 10.2.10.212.56690: P 3:6(3) ack 1 win 65529 <nop,nop,timestamp 27146219 3617561665> (DF) 19:03:19.659462 10.2.10.212.56690 > 10.1.12.11.8001: . ack 6 win 181 <nop,nop,timestamp 3617562713 27146219> (DF) 19:03:20.690719 10.1.12.11.8001 > 10.2.10.212.56690: P 6:9(3) ack 1 win 65529 <nop,nop,timestamp 27146230 3617562713> (DF) 19:03:20.690727 10.2.10.212.56690 > 10.1.12.11.8001: . ack 9 win 181 <nop,nop,timestamp 3617563744 27146230> (DF)
10.1.12.11 is the Win2k box, 10.2.10.212 is the Linux box. The socket buffer sizes are the defaults, so the scaling is most likely 2^2. The packets being exchanged at this point are just heartbeats.
On Tuesday I can try to capture a full session from the very begining, if you think it would help.
Thanks, -Ion - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |