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

[Jason Wang]

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?