[ovs-discuss] Current and max speed values static and not changing according to link load

Ben Pfaff blp at nicira.com
Mon Mar 23 21:01:10 UTC 2015


I don't think OpenFlow has any way to directly report the current
bitrate.  It could be calculated, however, by requesting flow
statistics periodically, then subtracting subsequent byte counts and
dividing by the time interval.

On Mon, Mar 23, 2015 at 08:53:12PM +0000, Rui Braz wrote:
> But in my command on mininet I specify the link speed to 50mbps and it still gives me the same value 10000000 which corresponds to 10gbps because that value is in kbps.
> 
> I saw a mail in mailing list from openflow that people could get the current transmit rate, however I don't know if they usede mininet and ovs. So I kinda think that this value is not "working properly" because I'm using ovs with mininet, however I'm not sure because there is no information on that matter. According to openflow spec the request I make should return the link max speed and current link speed.
> 
> So I just want to know if there's a way to obtain the current link speed or current transmit rate ? Or given what I'm using why it is not possible to know that.
> 
> Regards, 
> Nuno B.
> 
> ________________________________________
> De: Ben Pfaff <blp at nicira.com>
> Enviado: 23 de mar?o de 2015 20:22
> Para: Rui Braz
> Cc: mininet-discuss at lists.stanford.edu; discuss at openvswitch.org
> Assunto: Re: [ovs-discuss] Current and max speed values static and not changing according to link load
> 
> On Mon, Mar 23, 2015 at 07:23:02PM +0000, Rui Braz wrote:
> > It is giving me always 10mb no matter what
> > ("flow-node-inventory:current-speed": 10000000) and
> > ("flow-node-inventory:maximum-speed": 0). The current speed
> > according to documentation is the "Current port bit rate in
> > kbps". However is always 10000000, even though I'm not sending
> > packets on the link.
> 
> These are probably derived from OVS reports of the link rate (e.g. 10
> Mbps or some order of magnitude higher), not the number of bits
> actually flowing at any given time.
> 
> > Also when I do " s2 ovs-ofctl -Oopenflow13 show "s2" "I received the
> > following response: http://pastebin.com/HUwvJ1SR. Can someone
> > explain to me why the 'current' and 'speed' fields are not changing
> > according to the link load ?
> 
> OpenFlow reports the link rate not the number of bits flowing at any
> given time.



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