Improve DSCP/TOS bit behavior

[bmah888]

From jdugan.esnet on July 20, 2010 10:03:17

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: http://code.google.com/p/iperf/issues/detail?id=22

[bmah888]

From sethdelliott on August 03, 2010 15:12:19

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 -S 0x10 #IPTOS_LOWDELAY
iperf3 -c -S 0x08 #IPTOS_THROUGHPUT

Status: Fixed

[bmah888]

From richih@richih.org on August 06, 2010 13:38:36

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