[ovs-discuss] What is the role of ovsdb-server and vswitchd?

Aishwarya aishu85 at gmail.com
Wed Sep 21 18:46:36 UTC 2011


Hi Ben, Justin,

That was very helpful. Thanks! One of the slides say that the kernel module
has no flow expiration . I am guessing this means that as it gets to know
about more and more flows from vswitchd, these will always be there in the
kernel as long as it is loaded?

Also, If I have lets say 7000 flows, and send some traffic for each flow, so
that the kernel module ultimately knows about all the flows. How fast is its
lookup now when it starts receiving packets, lets say of the oldest flow?
Does it have some sort of a cache where it stores the last few flows? (how
big?)

Thanks,
Aish

On Tue, Sep 20, 2011 at 11:45 PM, Justin Pettit <jpettit at nicira.com> wrote:

> Ben's done a good job of answering your questions.  There are a couple of
> presentations and papers that may be worth looking at under the
> "Documentation" section of the openvswitch.org site.  Here's one in
> particular that provides a quick high-level overview of the architecture:
>
>        http://openvswitch.org/slides/OVS-Overview-110303.pdf
>
> --Justin
>
>
> On Sep 20, 2011, at 9:40 PM, Aishwarya wrote:
>
> > Ok. So what happens with other packets that belong to this same flow? Do
> they get routed without the help of vswitchd then? If yes, how does this
> happen?
> >
> > Thanks,
> > Aish
> >
> > On Tue, Sep 20, 2011 at 9:40 PM, Ben Pfaff <blp at nicira.com> wrote:
> > On Tue, Sep 20, 2011 at 09:36:30PM -0700, Aishwarya wrote:
> > > Thanks for your detailed reply. Does this mean that every time a packet
> > > arrives, it is first sent to the user process vswitchd and then sent
> back
> > > into the kernel for forwarding, which means there will be a
> kernel-to-user
> > > space and back to kernel space context switch for every packet that
> arrives?
> >
> > No.  There is one such transition for each new flow.
> >
> > _______________________________________________
> > discuss mailing list
> > discuss at openvswitch.org
> > http://openvswitch.org/mailman/listinfo/discuss
>
>
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