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

[Wen Congyang]

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.

Thanks
Wen Congyang

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