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Re: [L4s-discuss] Irregularities in results from L4S testing

rjmcmahon <rjmcmahon@rjmcmahon.com> Wed, 06 September 2023 05:04 UTC

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Date: Tue, 05 Sep 2023 22:04:47 -0700
From: rjmcmahon <rjmcmahon@rjmcmahon.com>
To: rjmcmahon <rjmcmahon=40rjmcmahon.com@dmarc.ietf.org>
Cc: Matteo Guarna S303434 <matteo.guarna@studenti.polito.it>, l4s-discuss@ietf.org
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Subject: Re: [L4s-discuss] Irregularities in results from L4S testing
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Also, if one only wants to monitor a single number, network power can be 
used. Here's a cubic & prague run, no L4S ECN forwarding plane. It seems 
prague outperforms cubic w/respect to network power because of the 
slightly lower write to read msg latency.

This is just two Rpi4s on the same switch.

root@raspberrypi:/usr/local/src/iperf2-code# iperf -s -i 1 -e
------------------------------------------------------------
Server listening on TCP port 5001 with pid 5418
Read buffer size:  128 KByte (Dist bin width=16.0 KByte)
TCP congestion control default cubic
TCP window size:  128 KByte (default)
------------------------------------------------------------
[  1] local 192.168.1.32%eth0 port 5001 connected with 192.168.1.33 port 
55328 (trip-times) (sock=4/cubic) (peer 2.1.10-master) 
(icwnd/mss/irtt=14/1448/216) on 2023-09-05 21:57:50.882 (PDT)
[ ID] Interval        Transfer    Bandwidth    Burst Latency 
avg/min/max/stdev (cnt/size) inP NetPwr  Reads=Dist
[  1] 0.00-1.00 sec  11.9 MBytes   100 Mbits/sec  
12.962/9.365/13.121/0.386 ms (95/131682)  161 KByte 965  
3406=3405:1:0:0:0:0:0:0
[  1] 1.00-2.00 sec  23.7 MBytes   199 Mbits/sec  
7.093/6.628/12.952/0.533 ms (190/130812)  170 KByte 3504  
7118=7114:4:0:0:0:0:0:0
[  1] 2.00-3.00 sec  35.7 MBytes   299 Mbits/sec  
5.385/4.284/7.023/0.191 ms (285/131168)  196 KByte 6942  
11437=11431:6:0:0:0:0:0:0
[  1] 3.00-4.00 sec  47.6 MBytes   400 Mbits/sec  
4.752/3.421/5.505/0.357 ms (381/131100)  232 KByte 10510  
2520=1512:13:995:0:0:0:0:0
[  1] 4.00-5.00 sec  59.5 MBytes   499 Mbits/sec  
3.048/2.853/5.050/0.181 ms (476/131100)  186 KByte 20475  
1782=827:3:11:941:0:0:0:0
[  1] 5.00-6.00 sec  71.5 MBytes   600 Mbits/sec  
3.965/2.918/4.632/0.417 ms (572/131071)  290 KByte 18910  
23200=22675:54:52:419:0:0:0:0
[  1] 6.00-7.00 sec  83.4 MBytes   699 Mbits/sec  
3.453/2.618/4.159/0.262 ms (667/131089)  295 KByte 25319  
44522=44521:1:0:0:0:0:0:0
[  1] 7.00-8.00 sec  95.3 MBytes   800 Mbits/sec  
3.000/2.289/3.525/0.218 ms (763/131003)  293 KByte 33318  
50682=50680:2:0:0:0:0:0:0
[  1] 8.00-9.00 sec   107 MBytes   900 Mbits/sec  
2.647/2.034/3.088/0.185 ms (858/131061)  291 KByte 42475  
56994=56993:1:0:0:0:0:0:0
[  1] 9.00-10.00 sec   111 MBytes   929 Mbits/sec  
2.326/2.019/2.735/0.093 ms (885/131160)  264 KByte 49903  
58385=58382:2:1:0:0:0:0:0
[  1] 10.00-11.00 sec   111 MBytes   929 Mbits/sec  
2.338/1.843/2.642/0.084 ms (886/131044)  265 KByte 49658  
58611=58609:1:1:0:0:0:0:0
[  1] 11.00-12.00 sec   111 MBytes   928 Mbits/sec  
2.387/2.139/2.495/0.071 ms (885/131142)  271 KByte 48625  
58583=58583:0:0:0:0:0:0:0
[  1] 12.00-13.00 sec   109 MBytes   917 Mbits/sec  
2.591/2.000/3.075/0.299 ms (875/131000)  290 KByte 44245  
57699=57699:0:0:0:0:0:0:0
[  1] 13.00-14.00 sec   109 MBytes   912 Mbits/sec  
2.728/2.024/3.277/0.280 ms (870/130997)  304 KByte 41772  
55068=55013:6:4:9:11:1:0:24
[  1] 14.00-15.00 sec   109 MBytes   915 Mbits/sec  
2.900/2.087/3.540/0.264 ms (872/131143)  324 KByte 39440  
35153=34696:1:0:113:107:0:0:236
[  1] 0.00-15.00 sec  1.17 GBytes   668 Mbits/sec  
3.129/1.843/13.121/1.370 ms (9563/131072)  298 KByte 26697  
525326=522306:95:1064:1482:118:1:0:260
[  2] local 192.168.1.32%eth0 port 5001 connected with 192.168.1.33 port 
56498 (trip-times) (sock=5/prague) (peer 2.1.10-master) 
(icwnd/mss/irtt=14/1448/189) on 2023-09-05 21:58:08.514 (PDT)
[ ID] Interval        Transfer    Bandwidth    Burst Latency 
avg/min/max/stdev (cnt/size) inP NetPwr  Reads=Dist
[  2] 0.00-1.00 sec  11.9 MBytes  99.9 Mbits/sec  
11.870/10.531/12.112/0.154 ms (95/131510)  147 KByte 1052  
5240=5240:0:0:0:0:0:0:0
[  2] 1.00-2.00 sec  23.7 MBytes   198 Mbits/sec  
6.602/6.376/11.912/0.514 ms (189/131224)  159 KByte 3757  
8896=8896:0:0:0:0:0:0:0
[  2] 2.00-3.00 sec  35.7 MBytes   300 Mbits/sec  
4.707/4.613/6.539/0.123 ms (286/130912)  171 KByte 7955  
14637=14637:0:0:0:0:0:0:0
[  2] 3.00-4.00 sec  47.6 MBytes   400 Mbits/sec  
3.772/3.705/4.678/0.062 ms (381/131085)  184 KByte 13240  
21490=21486:3:1:0:0:0:0:0
[  2] 4.00-5.00 sec  59.6 MBytes   500 Mbits/sec  
3.274/3.129/3.777/0.054 ms (476/131190)  200 KByte 19072  
30380=30376:3:1:0:0:0:0:0
[  2] 5.00-6.00 sec  71.5 MBytes   600 Mbits/sec  
2.877/2.838/3.342/0.033 ms (572/131042)  210 KByte 26051  
38172=38163:8:1:0:0:0:0:0
[  2] 6.00-7.00 sec  83.4 MBytes   700 Mbits/sec  
2.467/2.421/2.867/0.033 ms (667/131111)  211 KByte 35449  
37429=36701:727:1:0:0:0:0:0
[  2] 7.00-8.00 sec  95.3 MBytes   800 Mbits/sec  
2.489/2.236/2.940/0.058 ms (763/131007)  243 KByte 40166  
39746=38688:1005:49:3:1:0:0:0
[  2] 8.00-9.00 sec   107 MBytes   900 Mbits/sec  
2.203/2.083/2.495/0.027 ms (858/131077)  242 KByte 51060  
56449=56424:23:1:0:0:1:0:0
[  2] 9.00-10.00 sec   112 MBytes   937 Mbits/sec  
2.047/1.899/2.242/0.102 ms (894/131054)  234 KByte 57230  
58373=58368:3:1:0:0:1:0:0
[  2] 10.00-11.00 sec   111 MBytes   931 Mbits/sec  
2.269/1.841/2.544/0.150 ms (888/131079)  258 KByte 51298  
57990=57987:3:0:0:0:0:0:0
[  2] 11.00-12.00 sec   110 MBytes   925 Mbits/sec  
2.355/2.086/2.556/0.062 ms (882/131083)  266 KByte 49090  
57727=57726:1:0:0:0:0:0:0
[  2] 12.00-13.00 sec   110 MBytes   919 Mbits/sec  
2.265/2.060/2.517/0.029 ms (877/131046)  254 KByte 50740  
57241=57240:1:0:0:0:0:0:0
[  2] 13.00-14.00 sec   109 MBytes   915 Mbits/sec  
2.469/2.032/2.830/0.203 ms (873/131062)  276 KByte 46346  
56947=56946:1:0:0:0:0:0:0
[  2] 14.00-15.00 sec   109 MBytes   917 Mbits/sec  
2.490/1.292/3.128/0.283 ms (874/131086)  279 KByte 46013  
59386=59382:3:0:1:0:0:0:0
[  2] 0.00-15.00 sec  1.17 GBytes   669 Mbits/sec  
2.719/1.292/12.112/1.210 ms (9578/131072)  302 KByte 30772  
600299=598456:1781:55:4:1:2:0:0


root@raspberrypi:/usr/local/src/iperf2-code# iperf -c 192.168.1.32 -i 1 
--trip-times --fq-rate-step 100m --tcp-cca cubic -t 15
------------------------------------------------------------
Client connecting to 192.168.1.32, TCP port 5001 with pid 6055 (1/0 
flows/load)
Write buffer size: 131072 Byte
fair-queue socket pacing set to  100 Mbit/s (stepping rate by  100 
Mbit/s)
TCP congestion control set to cubic using cubic
TOS set to 0x0 (Nagle on)
TCP window size:  119 KByte (default)
Event based writes (pending queue watermark at 16384 bytes)
------------------------------------------------------------
[  1] local 192.168.1.33%eth0 port 55328 connected with 192.168.1.32 
port 5001 (prefetch=16384) (trip-times) (sock=3/cubic) 
(icwnd/mss/irtt=14/1448/254) (ct=0.41 ms) on 2023-09-05 21:57:50.882 
(PDT)
[ ID] Interval        Transfer    Bandwidth       Write/Err  Rtry     
Cwnd/RTT(var)  fq-rate  NetPwr
[  1] 0.00-1.00 sec  12.0 MBytes   101 Mbits/sec  96/0         0       
56K/309(175) us  100 Mbit/sec 40722
[  1] 1.00-2.00 sec  23.8 MBytes   199 Mbits/sec  190/0         0      
108K/274(47) us  200 Mbit/sec 90889
[  1] 2.00-3.00 sec  35.6 MBytes   299 Mbits/sec  285/0         0      
152K/395(111) us  300 Mbit/sec 94571
[  1] 3.00-4.00 sec  47.8 MBytes   401 Mbits/sec  382/0         0      
210K/415(100) us  400 Mbit/sec 120649
[  1] 4.00-5.00 sec  59.5 MBytes   499 Mbits/sec  476/0         0      
210K/420(113) us  500 Mbit/sec 148548
[  1] 5.00-6.00 sec  71.5 MBytes   600 Mbits/sec  572/0         0      
257K/354(99) us  600 Mbit/sec 211789
[  1] 6.00-7.00 sec  83.4 MBytes   699 Mbits/sec  667/0         0      
257K/372(116) us  700 Mbit/sec 235014
[  1] 7.00-8.00 sec  95.4 MBytes   800 Mbits/sec  763/0         0      
257K/358(106) us  800 Mbit/sec 279352
[  1] 8.00-9.00 sec   107 MBytes   900 Mbits/sec  858/0         0      
257K/383(134) us  900 Mbit/sec 293629
[  1] 9.00-10.00 sec   111 MBytes   928 Mbits/sec  885/0         0      
257K/1048(97) us 1.00 Gbit/sec 110686
[  1] 10.00-11.00 sec   111 MBytes   929 Mbits/sec  886/0         0      
257K/1027(80) us 1.10 Gbit/sec 113077
[  1] 11.00-12.00 sec   111 MBytes   929 Mbits/sec  886/0         0      
257K/1030(72) us 1.20 Gbit/sec 112747
[  1] 12.00-13.00 sec   109 MBytes   916 Mbits/sec  874/0         0      
257K/1374(67) us 1.30 Gbit/sec 83375
[  1] 13.00-14.00 sec   109 MBytes   912 Mbits/sec  870/0         0      
394K/1474(149) us 1.40 Gbit/sec 77363
[  1] 14.00-15.00 sec   109 MBytes   914 Mbits/sec  872/0         0      
394K/1592(88) us 1.50 Gbit/sec 71793
[  1] 0.00-15.01 sec  1.17 GBytes   668 Mbits/sec  9563/0         0      
394K/1660(205) us 50294

root@raspberrypi:/usr/local/src/iperf2-code# iperf -c 192.168.1.32 -i 1 
--trip-times --fq-rate-step 100m --tcp-cca prague -t 15
------------------------------------------------------------
Client connecting to 192.168.1.32, TCP port 5001 with pid 6058 (1/0 
flows/load)
Write buffer size: 131072 Byte
fair-queue socket pacing set to  100 Mbit/s (stepping rate by  100 
Mbit/s)
TCP congestion control set to prague using prague
TOS set to 0x0 (Nagle on)
TCP window size: 85.0 KByte (default)
Event based writes (pending queue watermark at 16384 bytes)
------------------------------------------------------------
[  1] local 192.168.1.33%eth0 port 56498 connected with 192.168.1.32 
port 5001 (prefetch=16384) (trip-times) (sock=3/prague) 
(icwnd/mss/irtt=14/1448/159) (ct=0.31 ms) on 2023-09-05 21:58:08.514 
(PDT)
[ ID] Interval        Transfer    Bandwidth       Write/Err  Rtry     
Cwnd/RTT(var)  fq-rate  NetPwr
[  1] 0.00-1.00 sec  12.0 MBytes   101 Mbits/sec  96/0         0       
28K/122(2) us  100 Mbit/sec 103140
[  1] 1.00-2.00 sec  23.6 MBytes   198 Mbits/sec  189/0         0       
67K/179(72) us  200 Mbit/sec 138394
[  1] 2.00-3.00 sec  35.8 MBytes   300 Mbits/sec  286/0         0      
103K/165(37) us  300 Mbit/sec 227191
[  1] 3.00-4.00 sec  47.6 MBytes   400 Mbits/sec  381/0         0      
181K/149(23) us  400 Mbit/sec 335157
[  1] 4.00-5.00 sec  59.6 MBytes   500 Mbits/sec  477/0         0      
236K/161(29) us  500 Mbit/sec 388331
[  1] 5.00-6.00 sec  71.5 MBytes   600 Mbits/sec  572/0         0      
261K/178(29) us  600 Mbit/sec 421198
[  1] 6.00-7.00 sec  83.4 MBytes   699 Mbits/sec  667/0         0      
261K/196(40) us  700 Mbit/sec 446046
[  1] 7.00-8.00 sec  95.4 MBytes   800 Mbits/sec  763/0         0      
349K/213(43) us  800 Mbit/sec 469521
[  1] 8.00-9.00 sec   107 MBytes   900 Mbits/sec  858/0         0      
418K/210(33) us  900 Mbit/sec 535523
[  1] 9.00-10.00 sec   112 MBytes   937 Mbits/sec  894/0         0      
418K/893(66) us 1.00 Gbit/sec 131219
[  1] 10.00-11.00 sec   111 MBytes   931 Mbits/sec  888/0         0      
418K/1001(57) us 1.10 Gbit/sec 116276
[  1] 11.00-12.00 sec   110 MBytes   925 Mbits/sec  882/0         0      
418K/1060(45) us 1.20 Gbit/sec 109062
[  1] 12.00-13.00 sec   110 MBytes   920 Mbits/sec  877/0         0      
418K/1236(66) us 1.30 Gbit/sec 93002
[  1] 13.00-14.00 sec   109 MBytes   915 Mbits/sec  873/0         0      
434K/1442(73) us 1.40 Gbit/sec 79352
[  1] 14.00-15.00 sec   109 MBytes   916 Mbits/sec  874/0         1      
267K/1427(116) us 1.50 Gbit/sec 80278
[  1] 0.00-15.01 sec  1.17 GBytes   669 Mbits/sec  9578/0         1      
267K/1357(84) us 61631

Bob
> Off topic, but iperf 2 provides latency information and queue depth
> (inP) via Little's law. Capacity info only I find as insufficient.
> 
> One can see bloat occur on both client & server at the 9-10 sec
> interval below. (Use --histograms for full data vs the central limit
> theorem (CLT) averaging.)
> 
> 
> [rjmcmahon@fedora iperf2-code]$ src/iperf -c 192.168.1.32 --fq-rate
> 100m -i 1 -e --trip-times --fq-rate-step 100m -t 15
> ------------------------------------------------------------
> Client connecting to 192.168.1.32, TCP port 5001 with pid 38101 (1/0 
> flows/load)
> Write buffer size: 131072 Byte
> fair-queue socket pacing set to  100 Mbit/s (stepping rate by  100 
> Mbit/s)
> TCP congestion control using cubic
> TOS set to 0x0 (Nagle on)
> TCP window size: 85.0 KByte (default)
> Event based writes (pending queue watermark at 16384 bytes)
> ------------------------------------------------------------
> [  1] local 192.168.1.103%enp4s0 port 57908 connected with
> 192.168.1.32 port 5001 (prefetch=16384) (trip-times) (sock=3)
> (icwnd/mss/irtt=14/1448/183) (ct=0.25 ms) on 2023-09-05 19:43:15.600
> (PDT)
> [ ID] Interval        Transfer    Bandwidth       Write/Err  Rtry
> Cwnd/RTT(var)  fq-rate  NetPwr
> [  1] 0.00-1.00 sec  12.1 MBytes   102 Mbits/sec  97/0         0
> 419K/498(150) us  100 Mbit/sec25530
> [  1] 1.00-2.00 sec  23.6 MBytes   198 Mbits/sec  189/0         0
> 419K/621(620) us  200 Mbit/sec39891
> [  1] 2.00-3.00 sec  35.5 MBytes   298 Mbits/sec  284/0         0
> 419K/648(436) us  300 Mbit/sec57445
> [  1] 3.00-4.00 sec  47.6 MBytes   400 Mbits/sec  381/0         0
> 419K/477(141) us  400 Mbit/sec104693
> [  1] 4.00-5.00 sec  59.5 MBytes   499 Mbits/sec  476/0         0
> 419K/590(241) us  500 Mbit/sec105746
> [  1] 5.00-6.00 sec  71.4 MBytes   599 Mbits/sec  571/0         0
> 419K/548(123) us  600 Mbit/sec136573
> [  1] 6.00-7.00 sec  83.4 MBytes   699 Mbits/sec  667/0         0
> 419K/560(199) us  700 Mbit/sec156116
> [  1] 7.00-8.00 sec  95.4 MBytes   800 Mbits/sec  763/0         0
> 419K/465(134) us  800 Mbit/sec215071
> [  1] 8.00-9.00 sec   107 MBytes   899 Mbits/sec  857/0         0
> 419K/376(153) us  900 Mbit/sec298747
> [  1] 9.00-10.00 sec   114 MBytes   952 Mbits/sec  908/0        65
> 1539K/13165(122) us 1.00 Gbit/sec9040
> [  1] 10.00-11.00 sec   112 MBytes   944 Mbits/sec  900/0         0
>  1681K/14367(120) us 1.10 Gbit/sec8211
> [  1] 11.00-12.00 sec   112 MBytes   942 Mbits/sec  898/0         0
>  1791K/15265(65) us 1.20 Gbit/sec7711
> [  1] 12.00-13.00 sec   112 MBytes   943 Mbits/sec  899/0         0
>  1879K/16038(133) us 1.30 Gbit/sec7347
> [  1] 13.00-14.00 sec   112 MBytes   937 Mbits/sec  894/0         1
>  1361K/11505(122) us 1.40 Gbit/sec10185
> [  1] 14.00-15.00 sec   112 MBytes   942 Mbits/sec  898/0         0
>  1456K/12278(94) us 1.50 Gbit/sec9586
> [  1] 0.00-15.02 sec  1.18 GBytes   676 Mbits/sec  9683/0        66
>  1457K/12545(108) us 0.000 bit/sec6736
> 
> root@raspberrypi:/usr/local/src/iperf2-code# iperf -s -i 1 -e
> ------------------------------------------------------------
> Server listening on TCP port 5001 with pid 5138
> Read buffer size:  128 KByte (Dist bin width=16.0 KByte)
> TCP congestion control default cubic
> TCP window size:  128 KByte (default)
> ------------------------------------------------------------
> [  1] local 192.168.1.32%eth0 port 5001 connected with 192.168.1.103
> port 57908 (trip-times) (sock=4) (peer 2.1.10-master)
> (icwnd/mss/irtt=14/1448/157) on 2023-09-05 19:43:15.601 (PDT)
> [ ID] Interval        Transfer    Bandwidth    Burst Latency
> avg/min/max/stdev (cnt/size) inP NetPwr  Reads=Dist
> [  1] 0.00-1.00 sec  11.9 MBytes   100 Mbits/sec
> 24.929/9.939/29.771/3.530 ms (95/131703)  314 KByte 502
> 2352=2300:45:3:4:0:0:0:0
> [  1] 1.00-2.00 sec  23.6 MBytes   198 Mbits/sec
> 12.855/8.090/26.138/2.290 ms (188/131414)  306 KByte 1922
> 6269=6261:8:0:0:0:0:0:0
> [  1] 2.00-3.00 sec  35.5 MBytes   298 Mbits/sec
> 8.420/5.288/13.054/1.076 ms (285/130718)  304 KByte 4424
> 11051=11045:6:0:0:0:0:0:0
> [  1] 3.00-4.00 sec  47.6 MBytes   399 Mbits/sec
> 6.262/3.938/8.724/0.766 ms (380/131219)  305 KByte 7963
> 15944=15942:2:0:0:0:0:0:0
> [  1] 4.00-5.00 sec  59.5 MBytes   499 Mbits/sec
> 4.995/3.115/6.492/0.600 ms (476/131061)  304 KByte 12490
> 30047=30046:1:0:0:0:0:0:0
> [  1] 5.00-6.00 sec  71.4 MBytes   599 Mbits/sec
> 4.240/3.438/5.199/0.251 ms (571/131164)  310 KByte 17664
> 22126=21624:2:3:497:0:0:0:0
> [  1] 6.00-7.00 sec  83.4 MBytes   699 Mbits/sec
> 3.714/3.018/4.399/0.208 ms (668/130881)  316 KByte 23540
> 2002=668:0:0:1334:0:0:0:0
> [  1] 7.00-8.00 sec  95.3 MBytes   800 Mbits/sec
> 3.143/2.520/3.888/0.185 ms (762/131191)  307 KByte 31806
> 50364=50349:0:0:15:0:0:0:0
> [  1] 8.00-9.00 sec   107 MBytes   900 Mbits/sec
> 2.783/2.223/3.222/0.164 ms (858/131050)  305 KByte 40398
> 57331=57330:1:0:0:0:0:0:0
> [  1] 9.00-10.00 sec   112 MBytes   941 Mbits/sec
> 12.503/2.421/34.417/4.081 ms (898/131036) 1.42 MByte 9411
> 59761=59732:3:2:3:1:2:1:17
> [  1] 10.00-11.00 sec   112 MBytes   941 Mbits/sec
> 14.793/13.931/15.672/0.381 ms (898/131051) 1.66 MByte 7955
> 62269=62268:1:0:0:0:0:0:0
> [  1] 11.00-12.00 sec   112 MBytes   941 Mbits/sec
> 15.887/15.140/16.612/0.321 ms (898/131053) 1.78 MByte 7408
> 62362=62361:1:0:0:0:0:0:0
> [  1] 12.00-13.00 sec   112 MBytes   941 Mbits/sec
> 16.753/16.106/17.360/0.267 ms (897/131198) 1.88 MByte 7025
> 62345=62343:2:0:0:0:0:0:0
> [  1] 13.00-14.00 sec   112 MBytes   941 Mbits/sec
> 17.225/7.698/34.284/2.035 ms (898/131052) 1.92 MByte 6832
> 61245=61225:3:0:0:0:0:0:17
> [  1] 14.00-15.00 sec   112 MBytes   941 Mbits/sec
> 13.048/12.377/13.694/0.279 ms (898/131054) 1.47 MByte 9020
> 62314=62314:0:0:0:0:0:0:0
> [  1] 0.00-15.01 sec  1.18 GBytes   676 Mbits/sec
> 10.616/2.223/34.417/5.913 ms (9683/131072) 1.17 MByte 7963
> 568650=566676:75:8:1853:1:2:1:34
> 
> 
> Bob
>> Greetings,
>> 
>> I am currently conducting research for my thesis on the L4S suite. As
>> part of my research, I have deployed a simple testbed to examine the
>> behavior of a TCP-Prague data flow when deployed in conjunction with a
>> TCP-Cubic flow on a congested, L4S-capable network link.
>> 
>> For the network configuration and host setup, I have utilized the
>> source code available at the following GitHub repository:
>> 
>> https://github.com/L4STeam/linux/tree/testing .
>> 
>> While my initial tests have been generally successful, I have
>> encountered two specific issues:
>> 
>> 1 - The TCP-Prague and TCP-Cubic flows do not seem to equitably share
>> available bandwidth. In some cases, TCP-Prague appears to consume up
>> to two/thirds of the channel's capacity.
>> 
>> 2 - Upon inspecting the packets to assess the correctness of the
>> protocol's behavior, I observed that the proportion of TCP-Prague ACK
>> packets with the TCP ECE (Explicit Congestion Notification Echo) flag
>> is approximately 5/9 of the total ACK packets, while the percentage of
>> transmitted packets marked by the queue remains consistently at around
>> 8%. While I did not anticipate a strict 1:1 ratio, this result still
>> strikes me as peculiar.
>> 
>> Additionally, I noted that all TCP-Prague packets inherently carry the
>> CWR (Congestion Window Reduced) flag by default. It appears to me (if
>> I'm not mistaken) to be an intentional implementation choice by the
>> developers, as detailed in the source code found at
>> https://github.com/L4STeam/linux/blob/testing/net/ipv4/tcp_prague.c ,
>> specifically beginning at line 53. I would appreciate confirmation
>> regarding this implementation choice and assurance that it does not
>> adversely impact its compliance with the standard.
>> 
>> I extend my sincere gratitude in advance to anyone who can provide
>> insights or assistance with these matters.
>> 
>> Best regards,
>> 
>> Matteo Guarna
>> 
>> 
>> P.s.
>> 
>> I someone wants a more detailed insight regarding my testplant and my
>> results, I had tried to ask for help by opening an issue on the
>> repository's github, where I provided a more in-depth description of
>> my experiment. The conversation is available here:
>> 
>> https://github.com/L4STeam/linux/issues/21

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