On May 15, 2013, at 2:14 AM, chenli wrote:

> I did some test again, and it's so strange that the back flow for ssh 
> connection needs the field of nw_tos=16.

I don't think this is strange.  I believe 16 is the TOS value for minimize 
delay, which makes sense for ssh, since it's interactive.  The server is likely 
setting it on purpose.

> If the field for nw_tos equals to 0, the flow can't match correctly. Just 
> like below

I'm not clear why this a problem.  If its really troublesome for some reason, 
you could always wildcard it...

> And how can I find the flow_mods that correspond to these flows in POX?

That depends on what application you're running in POX.  If you're using 
l2_learning, for example, it's wherever the flow_mod is in there.  l2_learning 
uses ofp_match.from_packet() to create a flow which exactly matches the packet 
it's given.  This includes the TOS field.  You could just insert a match.nw_tos 
= None to wildcard it...


-- Murphy

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