[pox-dev] POX - TCP redirection flows

[chenli]

Hi Murphy,


Thanks for your replying, and now I use wildcard the nw_tos field to avoid
the flow match problem.

But I want to ask why during the connection between OpenFlow switch and POX
controller, POX command line usually dump some information like below:

[packet                 ] (dhcp parse) warning DHCP packet data too short
to parse header: data len 86

Is this invoke by the arp broadcast or the other problems?

Thanks again.


2013/5/15 Murphy McCauley <murphy.mccauley at gmail.com>

> 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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