O.K.From where does topology application get the switch and link
information?
Does topology application inturn poll the switches via OpenFlow control
channel to get that information?
Or does it pre-compute and store it (somewhere) if I run the application
with
$ sudo ryu-manager --observe-links ryu/app/simple_switch.py
What I am trying to understand are the following.
1) Is the topology information stored in some data structure in the
controller ?
2) When I query the topology via (get_switch() and get_links() ) does it
impose any channel overhead on the control channle?
Thanks & Regards,
Karthik.
On 16 April 2014 09:33, FUJITA Tomonori <[email protected]>wrote:
> Hey,
>
> On Wed, 16 Apr 2014 09:24:15 +1200
> Karthik Sharma <[email protected]> wrote:
>
> > I was looking at the RYU source code I came across two structures or
> > classes.
> >
> > 1) ofp_event which contains events such as
> >
> > - EventOFPHello
> > - EventOFPSwitchFeatures
> > - EventOFPPortDescStatsReply
> > - EventOFPEchoRequest
> > - EventOFPErrorMsg
> >
> > 2) event which contains events such as
> >
> > - EventSwitchRequest
> > - EventSwitchReply
> > - EventLinkRequest
> > - EventLinkReply
> >
> > My questions are as follows
> >
> > 1) ofp_event looks like it is the OpenFlow negotiation between the switch
> > and the controller.
>
> Yes. They correspond to OpenFlow specs. When Ryu gets an OpenFlow
> message from a switch, the EventOFP* corresponding to it is delivered
> to applications subscribing to the event.
>
> What is event? event is used by ryu/topology/api.py to
> > get the toplogy information (about switches and links)
>
> 2) are used internally in ryu/topology and your appliction. When your
> application calls get_switch(), internally, your application sends
> EventSwitchRequest to the topology application, then the topology
> application sends back an EventSwitchReply to your applicaiton.
>
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