[ovs-dev] Megaflows Question

[Ben Pfaff]

On Wed, Sep 09, 2015 at 02:34:43PM +0800, openvswitcher wrote:
> But I don't know why the 'xxxxxx0x.xxxxxxxx.xxxxxxxx.xxxxxxxx' is calculated as the result.
> Why is it not "xxxxxxxx.xxxx0xxx.xxxxxxxx.xxxxxxxx" which can also be used to differ the
> 00001010.00000000.(=10.0) from 00001000.00001000(=8.8) ?

The algorithm is described in our NSDI 2015 paper:
https://www.usenix.org/conference/nsdi15/technical-sessions/presentation/pfaff

> And another problem is:
>  in the situation '0.0.0.0/2.0.0.0'  is used, if I add another flow 'nw_dst=9(bit=00001001).8.8.8 action output:200'
> then the actions will be not same with 'nw_dst=8.8.8.8' but the flow installed in kernel will make the packet 
> of which the ip destination is 9.8.8.8 not be upcalled to userspace by flow-miss, it will use the flow for '8.8.8.8'
>  in kernel. Is this right?

If the OpenFlow table changes, the kernel flow cache has to be
reexamined and sometimes updated.