Re: [Qemu-devel] [RFC PATCH v2 00/10] Add colo-proxy based on netfilter

[Jason Wang]

On 01/20/2016 06:34 PM, Wen Congyang wrote:
> On 01/20/2016 06:03 PM, Jason Wang wrote:
>>
>> On 01/20/2016 05:49 PM, Wen Congyang wrote:
>>> On 01/20/2016 05:20 PM, Jason Wang wrote:
>>>> On 01/20/2016 03:44 PM, Wen Congyang wrote:
>>>>>>> ...
>>>>>>> -chardev socket,id=comparer0,host=ip_primary,port=X,server,nowait
>>>>>>> -chardev socket,id=comparer1,host=ip_primary,port=Y,server,nowait
>>>>>>> -chardev socket,id=mirrorer0,host=ip_primary,port=Z,server,nowait
>>>>>>> -netdev tap,id=hn0
>>>>>>> -traffic-mirrorer netdev=hn0,id=t0,indev=comparer0,outdev=mirrorer0
>>>>>>> -colo-comparer primary_traffic=comparer0,secondary_traffic=comparer1
>>>>>>> ...
>>>>>>>
>>>>>>> packet comparer compares the packets from two chardev: comparer0 and
>>>>>>> comparer1.
>>>>>>> traffic-mirrorer mirror tx to secondary node through chardev mirrorer0,
>>>>>>> and mirror rx to packet comparer through chardev comparer0.
>>>>>>>
>>>>>>> In secondary node:
>>>>>>>
>>>>>>> ...
>>>>>>> -chardev socket,id=redirector0,host=ip_primary,port=Y
>>>>>>> -chardev socket,id=redirector1,host=ip_primary,port=Z
>>>>>>> -netdev tap,id=hn0
>>>>>>> -traffic-redirector 
>>>>>>> netdev=hn0,id,r0,indev=redirector0,outdev=redirector1
>>>>>>> -colo-rewriter netdev=hn0,id=c0
>>>>>>> ...
>>>>>>>
>>>>>>> traffic-redirector redirect the rx traffic from primary node through
>>>>>>> redirector0 and redirect the tx traffic to promary node through 
>>>>>>> redirector1.
>>>>>>> colo-rewriter rewrite seq number as a normal netfilter.
>>>>> What are traffic-mirrorer and colo-comparer, traffic-redirector, 
>>>>> colo-rewriter?
>>>>> A netfilter driver?
>>>> traffic-mirrorer/redirector is a type of netfilter that just
>>>> mirror/redirect packets between netdev and chardev (just the mirror
>>>> client/sever and redirect client/sever in the above graph)
>>>> colo-rewriter is a type of netfilter that did ack/seq adjust (just the
>>>> TCP rewriter in the above graph)
>>>> colo-comparer is a thread object that did packet comparing (similar to
>>>> "compare" in the above graph but not a netfiler)
>>> Thanks. I have another question:
>>> IIRC, both rx and tx packets walk through all netfilter objects in the same 
>>> order.
>>>
>>> tx packet(sent to the guest): we want that redirector hanldes it first
>>> rx packet(sent from the guest): we want that colo-rewriter handles it first
>>> Change the order or use two traffic-redirectors?
>>>
>>> Thanks
>>> Wen Congyang
>> Interesting question.
>>
>> Two redirectors sounds ok or maybe we can go through rx filters in a
>> reverse order?
> netdev <---> filter1 <----> filter2 <----> .... <----> emulated device <----> 
> guest
> So I think we can go through rx filters in a reverse order. But it changes
> the behavior. So I am not sure if we can do it.

I think we can. Both dump and buffer filter does not require strict
order, so it's a good time and change to do this.

>
> Thanks
> Wen Congyang
>
>>
>> .
>>
>
>