Intrepid Slow PPTP Performance - retransmits and lost ACKs
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
network-manager-pptp (Ubuntu) |
Triaged
|
Undecided
|
Unassigned |
Bug Description
Binary package hint: network-
I'm using a fresh install of Intrepid 64bit on a machine with 4GB of memory. I've got a PPTP tunnel running back to work. I quickly noticed that performance was very poor over this link. There are a lot of stalls; web pages take a very long time to render and SSH connections stall a lot. I may be a bit presumptuous in assuming this is a bug - but this issue is not present with Hardy 32bit. While diagnosing the issue I noticed a lot of packet buffering mesages in the syslog:
Nov 2 08:42:41 john00-desktop2 pptp[8338]: nm-pptp-
Nov 2 08:42:41 john00-desktop2 pptp[8338]: nm-pptp-
Nov 2 08:42:41 john00-desktop2 pptp[8338]: nm-pptp-
Nov 2 08:42:41 john00-desktop2 pptp[8338]: nm-pptp-
Nov 2 08:42:42 john00-desktop2 pptp[8338]: nm-pptp-
Nov 2 08:42:42 john00-desktop2 pptp[8338]: nm-pptp-
Nov 2 08:42:42 john00-desktop2 pptp[8338]: nm-pptp-
My Wireshark packet captures show a lot of retransmissions and duplicate ACK's which appear to be the cause of the performance problems:
18 39.050106 172.29.14.101 172.29.17.192 TCP [TCP Previous segment lost] [TCP segment of a reassembled PDU]
19 39.050145 172.29.17.192 172.29.14.101 TCP [TCP Dup ACK 15#1] 45754 > http [ACK] Seq=438 Ack=4333 Win=14592 Len=0 TSV=2398754 TSER=75797622 SLE=5777 SRE=6961
29 39.425900 172.29.14.101 172.29.17.192 TCP http > 45756 [ACK] Seq=1 Ack=453 Win=50540 Len=0 TSV=75797662 TSER=2398760
30 39.747035 172.29.14.101 172.29.17.192 TCP [TCP Previous segment lost] [TCP segment of a reassembled PDU]
31 39.747055 172.29.17.192 172.29.14.101 TCP [TCP Dup ACK 25#1] 45756 > http [ACK] Seq=453 Ack=1 Win=5888 Len=0 TSV=2398928 TSER=75797662 SLE=1445 SRE=1705
32 39.834203 172.29.14.101 172.29.17.192 HTTP [TCP Retransmission] HTTP/1.1 200 OK (text/html)
I'm not sure how to go about further diagnosing this issue. Perhaps it's related to other known issues with Network Manager. This is a test machine so I'm not afraid to break it.
Thank you,
John
I installed the 32bit version of Intrepid on my Dell laptop (fresh install). It's exhibiting the same problems but much worse. The PPTP tunnel is unusable. This all worked at one point during the alpha phase. Wish I find my install CD's so I could determine at what point it broke. Here is an excerpt of the syslog file:
Nov 2 20:43:21 john00-laptop pptp[6626]: nm-pptp- service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 82 (expecting 80, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 85 (expecting 84, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 91 (expecting 90, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 92 (expecting 90, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 95 (expecting 94, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 98 (expecting 97, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 114 (expecting 109, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 122 (expecting 118, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 123 (expecting 118, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 130 (expecting 129, lost or reordered) service- 6621 log[decaps_ gre:pptp_ gre.c:414] : buffering packet 131 (expecting 129, lost or reordered)
Nov 2 20:43:23 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:24 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:24 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:24 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:30 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:39 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:46 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:47 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:47 john00-laptop pptp[6626]: nm-pptp-
Nov 2 20:43:47 john00-laptop pptp[6626]: nm-pptp-