Public bug reported:
Summary:
TCP source ports assigned by autobind results in even number ports
almost always. This causes issues with LACP xmit_hash_policy layer3+4
policy as only the first nic in a two port bond will be utilized.
Details:
kurt@cypher:~$ lsb_release -rd
Description: Ubuntu 16.04.1 LTS
Release: 16.04
kurt@cypher:~$ uname -a
Linux cypher 4.4.0-59-generic #80-Ubuntu SMP Fri Jan 6 17:47:47 UTC 2017 x86_64
x86_64 x86_64 GNU/Linux
Example iperf run demonstrating source ports are sequentially moving up
by 2:
kurt@cypher:~$ iperf -t 30 -c saio -P 15
------------------------------------------------------------
Client connecting to saio, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[ 9] local 172.16.2.38 port 34520 connected with 172.16.2.32 port 5001
[ 3] local 172.16.2.38 port 34496 connected with 172.16.2.32 port 5001
[ 7] local 172.16.2.38 port 34498 connected with 172.16.2.32 port 5001
[ 5] local 172.16.2.38 port 34500 connected with 172.16.2.32 port 5001
[ 6] local 172.16.2.38 port 34502 connected with 172.16.2.32 port 5001
[ 4] local 172.16.2.38 port 34504 connected with 172.16.2.32 port 5001
[ 11] local 172.16.2.38 port 34506 connected with 172.16.2.32 port 5001
[ 13] local 172.16.2.38 port 34510 connected with 172.16.2.32 port 5001
[ 12] local 172.16.2.38 port 34508 connected with 172.16.2.32 port 5001
[ 16] local 172.16.2.38 port 34512 connected with 172.16.2.32 port 5001
[ 17] local 172.16.2.38 port 34514 connected with 172.16.2.32 port 5001
[ 10] local 172.16.2.38 port 34516 connected with 172.16.2.32 port 5001
[ 15] local 172.16.2.38 port 34522 connected with 172.16.2.32 port 5001
[ 8] local 172.16.2.38 port 34524 connected with 172.16.2.32 port 5001
[ 14] local 172.16.2.38 port 34518 connected with 172.16.2.32 port 5001
[ ID] Interval Transfer Bandwidth
[ 11] 0.0-30.0 sec 304 MBytes 85.0 Mbits/sec
[ 16] 0.0-30.0 sec 306 MBytes 85.5 Mbits/sec
[ 17] 0.0-30.0 sec 299 MBytes 83.6 Mbits/sec
[ 9] 0.0-30.0 sec 323 MBytes 90.3 Mbits/sec
[ 8] 0.0-30.0 sec 305 MBytes 85.4 Mbits/sec
[ 3] 0.0-30.0 sec 300 MBytes 83.8 Mbits/sec
[ 5] 0.0-30.0 sec 166 MBytes 46.3 Mbits/sec
[ 6] 0.0-30.0 sec 305 MBytes 85.3 Mbits/sec
[ 10] 0.0-30.0 sec 315 MBytes 88.0 Mbits/sec
[ 15] 0.0-30.0 sec 104 MBytes 29.1 Mbits/sec
[ 7] 0.0-30.0 sec 99.9 MBytes 27.9 Mbits/sec
[ 13] 0.0-30.0 sec 196 MBytes 54.8 Mbits/sec
[ 14] 0.0-30.1 sec 107 MBytes 29.7 Mbits/sec
[ 4] 0.0-30.1 sec 111 MBytes 30.9 Mbits/sec
[ 12] 0.0-30.1 sec 138 MBytes 38.4 Mbits/sec
[SUM] 0.0-30.1 sec 3.30 GBytes 942 Mbits/sec
Expected behaviour:
TCP autobind assigning source ports either sequentially by 1, or more
securely randomly.
Note that after multiple attempts TCP autobind may result in an odd
numbered source port, however it predominately results in even numbered
source ports.
Here is an example where one port was odd out of 15 ports. The result is
that LACP xmit_hash_policy layer3+4 is able to direct that connection
over a different nic and the resulting bandwidth is doubled (2x 1G nic
in LACP):
kurt@cypher:~$ iperf -t 30 -c saio -P 15
------------------------------------------------------------
Client connecting to saio, TCP port 5001
TCP window size: 85.0 KByte (default)
------------------------------------------------------------
[ 12] local 172.16.2.38 port 34676 connected with 172.16.2.32 port 5001
[ 4] local 172.16.2.38 port 34648 connected with 172.16.2.32 port 5001
[ 6] local 172.16.2.38 port 34650 connected with 172.16.2.32 port 5001
[ 3] local 172.16.2.38 port 34654 connected with 172.16.2.32 port 5001
[ 5] local 172.16.2.38 port 34652 connected with 172.16.2.32 port 5001
[ 7] local 172.16.2.38 port 34656 connected with 172.16.2.32 port 5001
[ 9] local 172.16.2.38 port 34658 connected with 172.16.2.32 port 5001
[ 13] local 172.16.2.38 port 34660 connected with 172.16.2.32 port 5001
[ 14] local 172.16.2.38 port 34664 connected with 172.16.2.32 port 5001
[ 10] local 172.16.2.38 port 34662 connected with 172.16.2.32 port 5001
[ 11] local 172.16.2.38 port 34666 connected with 172.16.2.32 port 5001
[ 17] local 172.16.2.38 port 34668 connected with 172.16.2.32 port 5001
[ 16] local 172.16.2.38 port 34672 connected with 172.16.2.32 port 5001
[ 15] local 172.16.2.38 port 34670 connected with 172.16.2.32 port 5001
[ 8] local 172.16.2.38 port 34673 connected with 172.16.2.32 port 5001
[ ID] Interval Transfer Bandwidth
[ 12] 0.0-30.0 sec 294 MBytes 82.2 Mbits/sec
[ 8] 0.0-30.0 sec 3.28 GBytes 940 Mbits/sec
[ 7] 0.0-30.0 sec 302 MBytes 84.4 Mbits/sec
[ 10] 0.0-30.0 sec 296 MBytes 82.7 Mbits/sec
[ 4] 0.0-30.0 sec 232 MBytes 64.9 Mbits/sec
[ 3] 0.0-30.0 sec 133 MBytes 37.3 Mbits/sec
[ 14] 0.0-30.0 sec 282 MBytes 78.7 Mbits/sec
[ 9] 0.0-30.0 sec 362 MBytes 101 Mbits/sec
[ 13] 0.0-30.0 sec 273 MBytes 76.2 Mbits/sec
[ 11] 0.0-30.0 sec 342 MBytes 95.5 Mbits/sec
[ 15] 0.0-30.0 sec 230 MBytes 64.2 Mbits/sec
[ 17] 0.0-30.0 sec 196 MBytes 54.8 Mbits/sec
[ 6] 0.0-30.1 sec 133 MBytes 37.1 Mbits/sec
[ 16] 0.0-30.1 sec 188 MBytes 52.4 Mbits/sec
[ 5] 0.0-30.1 sec 117 MBytes 32.5 Mbits/sec
[SUM] 0.0-30.1 sec 6.58 GBytes 1.88 Gbits/sec
This demonstrates that the LACP xmit_hash_policy layer3+4 configuration
is working correctly but due to the predominately even number source
ports, it primarily utilizes one nic.
** Affects: kernel-package (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1656394
Title:
TCP autobind almost always returns an even numbered port
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