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* [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218)
@ 2020-12-15  0:12 olg33
  2020-12-15 11:37 ` [Flent-users] " Toke Høiland-Jørgensen
                   ` (5 more replies)
  0 siblings, 6 replies; 7+ messages in thread
From: olg33 @ 2020-12-15  0:12 UTC (permalink / raw)
  To: tohojo/flent; +Cc: Subscribed

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Hi,

We are installing a new satellite link and we are using flent to run bandwidth testing. The idea is to saturate the link with marked and unmarked packets.

However initial results show that the test was not able to reach the maximum bandwidth downstream supported by the link which is about 60Mbps.
 
For unmarked traffic we ran the following test:
`flent rrul -H 10.111.40.252` 

For marked traffic we used the following test:
`flent rrul_var -H 10.111.40.252 --test-parameter bidir_streams=5 --test-parameter markings=11,13,15,19,21 `

On both cases we reached no more than 50% of the link capacity.

To rule out any problem with the link itself, we ran the following test:
`flent tcp_12down -H 10.111.40.252`

This time. we were able to reach saturation levels (60Mbps) of downstream traffic. Also ran iperf3 and obtained the same results

Do you see any reason why the rrul and rrul_var tests aren't being able to generate enough traffic to saturate the link? Maybe any parameter I'm missing or something? Or maybe that's normal, anyhow, I'd appreciate any comment on this matter. 

Thanks. 


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* [Flent-users] Re: [tohojo/flent] rrul tests are not being able to saturate link (#218)
  2020-12-15  0:12 [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218) olg33
@ 2020-12-15 11:37 ` Toke Høiland-Jørgensen
  2020-12-15 22:19 ` olg33
                   ` (4 subsequent siblings)
  5 siblings, 0 replies; 7+ messages in thread
From: Toke Høiland-Jørgensen @ 2020-12-15 11:37 UTC (permalink / raw)
  To: tohojo/flent; +Cc: Subscribed

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olg33 <notifications@github.com> writes:

> Hi,
>
> We are installing a new satellite link and we are using flent to run
> bandwidth testing. The idea is to saturate the link with marked and
> unmarked packets.
>
> However initial results show that the test was not able to reach the
> maximum bandwidth downstream supported by the link which is about
> 60Mbps.
>  
> For unmarked traffic we ran the following test:
> `flent rrul -H 10.111.40.252` 
>
> For marked traffic we used the following test:
> `flent rrul_var -H 10.111.40.252 --test-parameter bidir_streams=5 --test-parameter markings=11,13,15,19,21 `
>
> On both cases we reached no more than 50% of the link capacity.
>
> To rule out any problem with the link itself, we ran the following test:
> `flent tcp_12down -H 10.111.40.252`
>
> This time. we were able to reach saturation levels (60Mbps) of
> downstream traffic. Also ran iperf3 and obtained the same results
>
> Do you see any reason why the rrul and rrul_var tests aren't being
> able to generate enough traffic to saturate the link? Maybe any
> parameter I'm missing or something? Or maybe that's normal, anyhow,
> I'd appreciate any comment on this matter.

Hmm, when you say satellite link, I assume this has really high RTT,
right? This usually makes it really difficult for TCP to saturate the
connection; I believe providers try to improve on this with various
kinds of "accelerators" that mess with the TCP connection to try to
alleviate this problem. That could be failing when there's bidirectional
traffic?

Another thing to note is that when you're running bidirectional traffic
the bulk traffic will be competing with ACKs in each direction. In
particular, if there's a lot of queueing delay in the upstream, that
will delay the ACKs which can prevent TCP from ramping up properly on
the downstream. What kind of queueing is on the bottleneck link, and are
you seeing the latency increase?

By my guess the latter effect would be most likely, or maybe a
combination? You may be able to see something interesting if you capture
the traffic and look at some tcptrace plots of the transfers.

The RRUL test is deliberately designed to stress connections to induce
these sorts of weird failure cases, so I guess you could say it's not
unexpected. But obviously it's not an ideal functioning of the link :)


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* [Flent-users] Re: [tohojo/flent] rrul tests are not being able to saturate link (#218)
  2020-12-15  0:12 [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218) olg33
  2020-12-15 11:37 ` [Flent-users] " Toke Høiland-Jørgensen
@ 2020-12-15 22:19 ` olg33
  2020-12-17 23:01 ` olg33
                   ` (3 subsequent siblings)
  5 siblings, 0 replies; 7+ messages in thread
From: olg33 @ 2020-12-15 22:19 UTC (permalink / raw)
  To: tohojo/flent; +Cc: flent-users, Comment

[-- Attachment #1: Type: text/plain, Size: 533 bytes --]

Thanks,

Yes indeed, we mainly use TCP spoofing in our modem setup to address the delay issue. However, we were getting even worse results. We turned it off temporarily and testing improved, but that left us exposed to the ACK issues you just mentioned. We'll look into tweaking the spoofing feature to see if we can get better results. Thanks again for your input.

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* [Flent-users] Re: [tohojo/flent] rrul tests are not being able to saturate link (#218)
  2020-12-15  0:12 [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218) olg33
  2020-12-15 11:37 ` [Flent-users] " Toke Høiland-Jørgensen
  2020-12-15 22:19 ` olg33
@ 2020-12-17 23:01 ` olg33
  2020-12-17 23:13 ` Toke Høiland-Jørgensen
                   ` (2 subsequent siblings)
  5 siblings, 0 replies; 7+ messages in thread
From: olg33 @ 2020-12-17 23:01 UTC (permalink / raw)
  To: tohojo/flent; +Cc: flent-users, Comment

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In a related issue, It took our attention that whenever we run a rrul or rrul_var test, upload traffic seems to be absent.

Below examples were performed with two servers connected back-to-back with no router in between to rule out any blockage (they connect using an ethernet switch with ports in the same Vlan).
 
 `$ flent rrul_var -H 172.16.1.40 --test-parameter bidir_streams=6 --test-parameter markings=11,13,15,17,19,21`

Summary of rrul_var test run from 2020-12-17 21:34:16.260047

 Ping (ms) avg         :             2.65          N/A ms              350
 Ping (ms)::ICMP       :            6.62         8.37 ms              350
 Ping (ms)::UDP 0 (11) :         1.99         0.14 ms              350
 Ping (ms)::UDP 1 (13) :         1.98         0.14 ms              350
 Ping (ms)::UDP 2 (15) :         1.96         0.14 ms              350
 Ping (ms)::UDP 3 (17) :         2.00         0.14 ms              350
 Ping (ms)::UDP 4 (19) :         2.00         0.14 ms              350
 Ping (ms)::UDP 5 (21) :         1.99         0.14 ms              350
 TCP download avg      :       156.53          N/A Mbits/s          350
 TCP download sum      :       939.18          N/A Mbits/s          350
 TCP download::0 (11)  :       190.43       171.36 Mbits/s         350  ---> OK
 TCP download::1 (13)  :       166.60       170.35 Mbits/s         350
 TCP download::2 (15)  :       143.99       156.95 Mbits/s         350
 TCP download::3 (17)  :       171.11       170.65 Mbits/s         350
 TCP download::4 (19)  :       110.92        94.05 Mbits/s         350
 TCP download::5 (21)  :       156.13         0.01 Mbits/s         350
 TCP totals            :              939.87          N/A Mbits/s         350
 TCP upload avg        :         0.12               N/A Mbits/s         350
 TCP upload sum        :        0.69               N/A Mbits/s         350
 TCP upload::0 (11)    :         0.19              0.18 Mbits/s         350  ---> No data
 TCP upload::1 (13)    :         0.10              0.17 Mbits/s         350
 TCP upload::2 (15)    :         0.04              0.07 Mbits/s         350
 TCP upload::3 (17)    :         0.14              0.13 Mbits/s         350
 TCP upload::4 (19)    :         0.09              0.13 Mbits/s         350
 TCP upload::5 (21)    :         0.13              0.14 Mbits/s         350

Now, if we run a tcp_12up test, we see upstream traffic:

 Ping (ms) ICMP :        2.22         2.55 ms                  350
 TCP upload avg :       41.77          N/A Mbits/s          350
 TCP upload sum :     501.25          N/A Mbits/s         350
 TCP upload::1  :        38.43        38.24 Mbits/s          350
 TCP upload::10 :        40.92        39.39 Mbits/s         350
 TCP upload::11 :        42.97        41.55 Mbits/s         350
 TCP upload::12 :        46.13        39.80 Mbits/s         350
 TCP upload::2  :        46.77        44.63 Mbits/s         350
 TCP upload::3  :        40.24        39.21 Mbits/s         350
 TCP upload::4  :        40.75        40.54 Mbits/s         350
 TCP upload::5  :        40.41        38.85 Mbits/s         350
 TCP upload::6  :        42.30        40.38 Mbits/s         350
 TCP upload::7  :        41.68        40.38 Mbits/s         350
 TCP upload::8  :        40.70        39.47 Mbits/s         350
 TCP upload::9  :        39.95        40.17 Mbits/s         350

Apparently, on bi-directional tests, upload traffic doesn't show, but if we run a Upsteram-only test, it works.  

Traffic graphs on port connecting the servers show that indeed there is not Upstream traffic during testing.

Upload traffic must be present, otherwise how the second server is replying?

 Is there any way to make upload traffic show up on rrul testing?


Thanks.

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* [Flent-users] Re: [tohojo/flent] rrul tests are not being able to saturate link (#218)
  2020-12-15  0:12 [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218) olg33
                   ` (2 preceding siblings ...)
  2020-12-17 23:01 ` olg33
@ 2020-12-17 23:13 ` Toke Høiland-Jørgensen
  2020-12-18 17:45 ` olg33
  2021-01-13 17:24 ` Toke Høiland-Jørgensen
  5 siblings, 0 replies; 7+ messages in thread
From: Toke Høiland-Jørgensen @ 2020-12-17 23:13 UTC (permalink / raw)
  To: tohojo/flent; +Cc: flent-users, Comment

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olg33 <notifications@github.com> writes:

> In a related issue, It took our attention that whenever we run a rrul or rrul_var test, upload traffic seems to be absent.
>
> Below examples were performed with two servers connected back-to-back
> with no router in between to rule out any blockage (they connect using
> an ethernet switch with ports in the same Vlan).

Erm, that does sound odd! Only obvious thing I can immediately think of
is maybe the network card is running in half-duplex mode? Did you check
the output of ethtool for the interface you're using?

Otherwise, to debug further you can try running with -L and looking at
the netperf output in the log file to see if there's any obvious
pointers there...


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* [Flent-users] Re: [tohojo/flent] rrul tests are not being able to saturate link (#218)
  2020-12-15  0:12 [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218) olg33
                   ` (3 preceding siblings ...)
  2020-12-17 23:13 ` Toke Høiland-Jørgensen
@ 2020-12-18 17:45 ` olg33
  2021-01-13 17:24 ` Toke Høiland-Jørgensen
  5 siblings, 0 replies; 7+ messages in thread
From: olg33 @ 2020-12-18 17:45 UTC (permalink / raw)
  To: tohojo/flent; +Cc: flent-users, Comment

[-- Attachment #1: Type: text/plain, Size: 1868 bytes --]

Hi tohojo,

Yes, I found the problem. The switch where our servers are connected had other servers and one of them had a port configured  by mistake the same Vlan of our piont-to-point connection. In principle that may not be a big deal, but once it was corrected I'm was able to push almost a Gig Up/Down:

 TCP download avg      :       133.64          N/A Mbits/s          351
 TCP download sum      :       935.50          N/A Mbits/s         351 ---------> OK
 TCP download::0 (11)  :       123.63       123.19 Mbits/s        351
 TCP download::1 (13)  :       121.54       121.51 Mbits/s        351
 TCP download::2 (15)  :       121.08       122.05 Mbits/s        351
 TCP download::3 (17)  :       121.59       121.58 Mbits/s        351
 TCP download::4 (19)  :        77.91        78.98 Mbits/s          351
 TCP download::5 (21)  :       244.72       244.05 Mbits/s        351
 TCP download::6 (25)  :       125.03       124.48 Mbits/s        351
 TCP totals            :            1871.57          N/A Mbits/s         351
 TCP upload avg        :       133.72          N/A Mbits/s           351
 TCP upload sum        :       936.07          N/A Mbits/s          351 ---------> OK
 TCP upload::0 (11)    :       135.29       134.01 Mbits/s         351
 TCP upload::1 (13)    :       134.59       134.75 Mbits/s         351
 TCP upload::2 (15)    :       131.10       131.34 Mbits/s         351
 TCP upload::3 (17)    :       131.24       131.24 Mbits/s         351
 TCP upload::4 (19)    :       134.21       134.62 Mbits/s         351
 TCP upload::5 (21)    :       134.76       134.69 Mbits/s         351
 TCP upload::6 (25)    :       134.88       134.74 Mbits/s         351
 

Thanks!

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* [Flent-users] Re: [tohojo/flent] rrul tests are not being able to saturate link (#218)
  2020-12-15  0:12 [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218) olg33
                   ` (4 preceding siblings ...)
  2020-12-18 17:45 ` olg33
@ 2021-01-13 17:24 ` Toke Høiland-Jørgensen
  5 siblings, 0 replies; 7+ messages in thread
From: Toke Høiland-Jørgensen @ 2021-01-13 17:24 UTC (permalink / raw)
  To: tohojo/flent; +Cc: flent-users, Comment

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Closed #218.

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end of thread, other threads:[~2021-01-13 17:24 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-12-15  0:12 [Flent-users] [tohojo/flent] rrul tests are not being able to saturate link (#218) olg33
2020-12-15 11:37 ` [Flent-users] " Toke Høiland-Jørgensen
2020-12-15 22:19 ` olg33
2020-12-17 23:01 ` olg33
2020-12-17 23:13 ` Toke Høiland-Jørgensen
2020-12-18 17:45 ` olg33
2021-01-13 17:24 ` Toke Høiland-Jørgensen

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