Improve DSCP/TOS bit behavior

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Richard Hartmann <richih.mailinglist@gmail.com> suggested:

One follow-up: It would be nice if the iperf server could set
DSCP/TOS bits, as well. If ACKs are shaped away, things start
to suck.

I would envision two modes:

1) -S for servers: Set default DSCP value for all outgoing packets

which is overridded by

2) If you receive a packet with DSCP bit vector foo, set the same
for replies to that packet/client.

I'd like to verify that #2 is good netiquette before implementing it.  However, 
#1 should definitely be implemented and be part of the client-server parameter 
exchange.

Original issue reported on code.google.com by jdugan.e...@gmail.com on 20 Jul 2010 at 5:03

[GoogleCodeExporter]

This feature has been added to Iperf3. There isn't a way to implement #2 with 
the sockets API as one cannot read the IP header on a per packet basis to get 
the DSCP bit vector.

You can now set the DSCP/TOS bit vector using the -S <hexadecimal/decimal/octal 
number> client option. The option is exchanged with the server, so there is no 
need to set -S for the server.

Examples:
iperf3 -c <host> -S 0x10   #IPTOS_LOWDELAY
iperf3 -c <host> -S 0x08   #IPTOS_THROUGHPUT

Original comment by sethdell...@gmail.com on 3 Aug 2010 at 10:12

• Changed state: Fixed

[GoogleCodeExporter]

Can you make the server print the TOS/DSCP bit vector if any? That way, you can 
always see what's happening.

Thanks for the work you did already!
Richard

Original comment by ric...@richih.org on 6 Aug 2010 at 8:38