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Date:      Tue, 16 Mar 2021 06:55:54 -0400
From:      Blake Hartshorn <contact@blakehartshorn.com>
To:        tuexen@freebsd.org
Cc:        freebsd-net@freebsd.org
Subject:   Re: Severe IPv6 TCP transfer issues on 13.0-RC1 and RC2
Message-ID:  <10847992.4GmZMkJedg@thinkbook>
In-Reply-To: <E1346D9D-F1E0-4ABC-89D6-33BC77705771@freebsd.org>
References:  <5753280.1HxCrU2fYu@thinkbook> <E1346D9D-F1E0-4ABC-89D6-33BC77705771@freebsd.org>

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Hi Michael,

I've attached tcpdumps for port 80 on both sides of a bad transfer, using 2 VMs in the same datacenter, FreeBSD 13 serving and 12 as a client. A friend of mine suggested I also run some tests with iperf3, so pasting those results below. You'll see it going fast in one direction and crawling in the other on TCP. There's also some disparity on UDP. 

TCP:
[ ID][Role] Interval           Transfer     Bitrate         Retr  Cwnd
[  5][TX-C]   0.00-1.00   sec  27.7 MBytes   233 Mbits/sec  342   26.7 KBytes       
[  7][RX-C]   0.00-1.00   sec  4.18 KBytes  34.3 Kbits/sec                  
[  5][TX-C]   1.00-2.00   sec  15.8 MBytes   132 Mbits/sec  249   52.0 KBytes       
[  7][RX-C]   1.00-2.00   sec  4.18 KBytes  34.3 Kbits/sec                  
[  5][TX-C]   2.00-3.00   sec  13.7 MBytes   115 Mbits/sec  307   15.4 KBytes       
[  7][RX-C]   2.00-3.00   sec  4.18 KBytes  34.3 Kbits/sec                  
[  5][TX-C]   3.00-4.00   sec  14.5 MBytes   121 Mbits/sec  260   22.4 KBytes       
[  7][RX-C]   3.00-4.00   sec  4.18 KBytes  34.3 Kbits/sec                  
[  5][TX-C]   4.00-5.00   sec  14.3 MBytes   120 Mbits/sec  240   37.9 KBytes       
[  7][RX-C]   4.00-5.00   sec  5.58 KBytes  45.7 Kbits/sec                  
[  5][TX-C]   5.00-6.00   sec  17.7 MBytes   149 Mbits/sec  363   15.4 KBytes       
[  7][RX-C]   5.00-6.00   sec  4.18 KBytes  34.3 Kbits/sec                  
[  5][TX-C]   6.00-7.00   sec  14.8 MBytes   124 Mbits/sec  287   8.38 KBytes       
[  7][RX-C]   6.00-7.00   sec  5.58 KBytes  45.7 Kbits/sec                  
[  5][TX-C]   7.00-8.00   sec  14.7 MBytes   123 Mbits/sec  293   28.1 KBytes       
[  7][RX-C]   7.00-8.00   sec  4.18 KBytes  34.3 Kbits/sec                  
[  5][TX-C]   8.00-9.00   sec  11.9 MBytes   100 Mbits/sec  325   18.3 KBytes       
[  7][RX-C]   8.00-9.00   sec  4.18 KBytes  34.3 Kbits/sec                  
[  5][TX-C]   9.00-10.00  sec  14.3 MBytes   120 Mbits/sec  315   39.3 KBytes       
[  7][RX-C]   9.00-10.00  sec  4.18 KBytes  34.3 Kbits/sec                  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID][Role] Interval           Transfer     Bitrate         Retr
[  5][TX-C]   0.00-10.00  sec   159 MBytes   134 Mbits/sec  2981             sender
[  5][TX-C]   0.00-10.00  sec   159 MBytes   134 Mbits/sec                  receiver
[  7][RX-C]   0.00-10.00  sec  77.0 KBytes  63.1 Kbits/sec   65             sender
[  7][RX-C]   0.00-10.00  sec  44.6 KBytes  36.6 Kbits/sec                  receiver
-----------------------------------------------------------------------------------------------------------


UDP:
[ ID][Role] Interval           Transfer     Bitrate         Jitter    Lost/Total Datagrams
[  5][TX-C]   0.00-1.00   sec  81.6 MBytes   685 Mbits/sec            67798  
[  7][RX-C]   0.00-1.00   sec  8.80 MBytes  73.8 Mbits/sec  0.255 ms  54070/60475 (89%)  
[  5][TX-C]   1.00-2.00   sec  72.7 MBytes   610 Mbits/sec            64802  
[  7][RX-C]   1.00-2.00   sec  8.52 MBytes  71.5 Mbits/sec  0.154 ms  68912/75116 (92%)  
[  5][TX-C]   2.00-3.00   sec  73.7 MBytes   618 Mbits/sec            64158  
[  7][RX-C]   2.00-3.00   sec  8.52 MBytes  71.5 Mbits/sec  0.276 ms  67738/73945 (92%)  
[  5][TX-C]   3.00-4.00   sec  76.6 MBytes   643 Mbits/sec            63521  
[  7][RX-C]   3.00-4.00   sec  8.55 MBytes  71.8 Mbits/sec  0.160 ms  68647/74874 (92%)  
[  5][TX-C]   4.00-5.00   sec  76.1 MBytes   638 Mbits/sec            64614  
[  7][RX-C]   4.00-5.00   sec  8.55 MBytes  71.7 Mbits/sec  0.461 ms  67542/73767 (92%)  
[  5][TX-C]   5.00-6.00   sec  75.9 MBytes   637 Mbits/sec            64834  
[  7][RX-C]   5.00-6.00   sec  8.57 MBytes  71.9 Mbits/sec  0.297 ms  71565/77806 (92%)  
[  5][TX-C]   6.00-7.00   sec  73.0 MBytes   613 Mbits/sec            63639  
[  7][RX-C]   6.00-7.00   sec  8.40 MBytes  70.5 Mbits/sec  0.199 ms  69545/75663 (92%)  
[  5][TX-C]   7.00-8.00   sec  74.6 MBytes   626 Mbits/sec            65030  
[  7][RX-C]   7.00-8.00   sec  8.78 MBytes  73.6 Mbits/sec  0.254 ms  67173/73566 (91%)  
[  5][TX-C]   8.00-9.00   sec  75.0 MBytes   629 Mbits/sec            64848  
[  7][RX-C]   8.00-9.00   sec  8.77 MBytes  73.5 Mbits/sec  0.298 ms  70932/77315 (92%)  
[  5][TX-C]   9.00-10.00  sec  74.5 MBytes   625 Mbits/sec            64487  
[  7][RX-C]   9.00-10.00  sec  8.71 MBytes  73.1 Mbits/sec  0.185 ms  68268/74612 (91%)  
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID][Role] Interval           Transfer     Bitrate         Jitter    Lost/Total Datagrams
[  5][TX-C]   0.00-10.00  sec   754 MBytes   632 Mbits/sec  0.000 ms  0/647731 (0%)  sender
[  5][TX-C]   0.00-10.12  sec   105 MBytes  87.2 Mbits/sec  0.245 ms  571090/647649 (88%)  receiver
[  7][RX-C]   0.00-10.00  sec  1009 MBytes   846 Mbits/sec  0.000 ms  0/761013 (0%)  sender
[  7][RX-C]   0.00-10.12  sec  86.2 MBytes  71.4 Mbits/sec  0.185 ms  674392/737139 (91%)  receiver




On Tuesday, March 16, 2021 4:16:15 AM EDT tuexen@freebsd.org wrote:
> > On 15. Mar 2021, at 12:56, Blake Hartshorn <contact@blakehartshorn.com> wrote:
> > 
> > The short version, when I use FreeBSD 13, delivering data can take 5 minutes for 1MB over SSH or HTTP when using IPv6. This problem does not happen with IPv4. I installed FreeBSD 12 and Linux on that same device, neither had the problem.
> > 
> > Did some troubleshooting with Linode, have ultimately ruled the network itself out at this point. When the server is on FreeBSD 13, it can download quickly over IPv6, but not deliver. Started investigating after noticing my SSH session was lagging when cat'ing large files or running builds. This problem even occurs between VMs in the same datacenter. I generated a 1MB file of base64 garbage served by nginx for testing. IPv6 is being configured by SLAAC and on both 12 and 13 installs was setup by the installer. Linode uses Linux/KVM hosts for their virtual machines so it's running on that virtual adapter.
> > 
> > I asked on the forums, another user recommended going to the mailing lists instead. Does anyone know if config settings need to be different on 13? Did I maybe just find a real issue? I can provide any requested details. Thanks!
> Could you prove a .pcap tracefile, one from the sender, one from the recevier, of
> a TCP/IPv6 connection, which doesn't work as expected. For example, use your 1MB
> base64 garbage transfer.
> 
> Best regardes
> Michael
> > 
> > 
> > _______________________________________________
> > freebsd-net@freebsd.org mailing list
> > https://lists.freebsd.org/mailman/listinfo/freebsd-net
> > To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
> 
> 



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