Hi,
Inline
On Thu, Apr 12, 2012 at 11:29 PM, Weiyang Mo <[email protected]>wrote:
> Hi,all,
>
> I am studying the example pyswitch.py.I am a new learner and I understand
> most of them, but few lines are not clear to me.
>
> The following lines:
>
> dst = inst.st[dpid][srcaddr]
> if dst[0] != inport:
> log.msg('MAC has moved from '+str(dst)+'to'+str(inport),
> system='pyswitch')
>
> I am confused that why using str(dst) not str(dst[0]), does dst[0]
> represent an old inport?
>
I think you are right. It will print out the full tuple stored instead of
just the old port.
>
>
> Does dst[0] ,dst[1], dst[2] represent the inport, time and packet?
>
Yes via
inst.st[dpid][srcaddr] = (inport, time(), packet)
Additionally,should I assign the new inport to the inst.st[dpid][srcaddr]?
> Just use inst.st[dpid][srcaddr][0]=inport ?
>
>
No you can not update it that way since it uses a tuple. You could change
it to a list or you would have to do:
inst.st[dpid][scraddr] = (new_port, inst.st[dpid][scraddr][1],
inst.st[dpid][scraddr][2])
# assuming we wanted the old time and packet.
Thanks very much
>
> Weiyang
>
Aaron
--
Aaron O. Rosen
Masters Student - Network Communication
306B Fluor Daniel
