perfSONAR User Q&A and Other Discussion

[Andrew Lake <>]

Hi,

It looks like you are correct that powstream does not support the -D option for setting the TOS bits. The powstream tool should not be letting it through, I will file an issue. The "owping" command (the non-streaming version of powstream) does support -D which I am guessing is the source of the confusion in the code. We should update the tool to prevent this and the GUIs as well. It's not clear to me why that feature is not implemented in powstream. The TODO you found is pretty old, so not sure if there is some reason I am not aware for why it did not get added.

In tools like iperf3 and owping where the option is supported, they just set the DSCP bits in the IP header. Its up to the network devices the generated packets traverse to enforce any desired traffic control based on the IP header value.

Hope that helps,

Andy

On Wed, Oct 10, 2018 at 12:47 PM <> wrote:

When setting ToS bits using the MeshConfig GUI Portal, all of our owamp tests
begin to fail -

logs indicate "invalid option -- 'D'", where -D is used to apply the tos_bits
parameter defined in a meshconfig

here is the full log -

[latency] powstream returned an error on startup for 75 consectutive attempts.
Giving up. This is the error it reported: /usr/bin/powstream: invalid option
-- 'D' powstream: usage: powstream [arguments] testaddr [servaddr] [arguments]
are as follows: -h print this message and exit [Test Args] -t sets the tests
direction from client to server -c count number of test packets (per complete
session) -E endDelay time to wait before sending stop-session message -i wait
mean average time between packets (seconds) -L timeout maximum time to wait
for a packet (seconds) -P portrange test port range to use (must contain at
least 2 ports) -s padding size of the padding added to each packet (bytes) -z
delayStart time to wait before starting first test (seconds) [Connection Args]
-4 use IPv4 only -6 use IPv6 only -A authmode requested modes:
[A]uthenticated, [E]ncrypted, [O]pen -k pffile pass-phrase file to use with
Authenticated/Encrypted modes -S srcaddr specify the local address or
interface for control connection and tests -u username username to use with
Authenticated/Encrypted modes -I retryDelay time to wait between failed
connections (default: 60 seconds) [Output Args] -b bucketWidth create summary
files with buckets(seconds) -d dir directory to save session file in -e
facility syslog facility to log to -g loglevel severity log messages to report
to syslog Valid values: NONE, FATAL, WARN, INFO, DEBUG, ALL -N count number of
test packets (per sub-session) -p print filenames to stdout -R Only send
messages to syslog (not STDERR) -v include more verbose output -U Adds UNIX
timestamps to summary results Version: 3.5.7-1 [powstream]

According to this txt file in the perfSONAR repo
-https://github.com/perfsonar/owamp/blob/master/TODO.txt, from 2008, testing
-D for setting dscp bits is/was a TODO item.

Using -D to set dscp doesnt break bwctl tests like it does for owamp, but the
ToS bits do not get applied to the traffic.

When the meshconfig is updated to no longer set the ToS bits, our owamp tests
do not recover, and continue to log the same '--D' error flag, well after the
updated mesh is taken by pscheduler.

This failure should be able to be replicated if you use the MeshConfig GUI to
set ToS bits in a given owamp test spec.

Questions:

Does anyone know what the current state of this feature is? Is setting DSCP in
perfSONAR tests supported and is the GUI is not the proper way to set the
meshconfig for it? If it is supported, what would the proper way to go about
setting these bits so that they get applied to traffic?

Also, I was wondering how perfSONAR implements setting the DSCP bits? The tool
does not appear to be using traffic control.