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From: Jason Wang <jasowang@redhat.com>
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Date: Wed, 29 Jun 2016 09:55:03 +0800
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Subject: Re: [Qemu-devel] [RFC PATCH 3/3] filter-rewriter: rewrite tcp
 packet to keep secondary connection
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To: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Yang Hongyang <hongyang.yang@easystack.cn>, "eddie . dong" <eddie.dong@intel.com>, qemu devel <qemu-devel@nongnu.org>, Li Zhijian <lizhijian@cn.fujitsu.com>, zhanghailiang <zhang.zhanghailiang@huawei.com>



On 2016=E5=B9=B406=E6=9C=8828=E6=97=A5 14:33, Zhang Chen wrote:
>>>
>>>>
>>>>> primary guest response=20
>>>>> pkt(seq=3Dprimary_seq+1,ack=3Dclient_seq+1+data_len,flag=3DACK)
>>>>> secondary guest response=20
>>>>> pkt(seq=3Dsecondary_seq+1,ack=3Dclient_seq+1+data_len,flag=3DACK)
>>>>
>>>> Is ACK a must here?
>>>
>>> Yes.
>>>
>>
>> Looks not, e.g what happens if guest does not use piggybacking acks?
>>
>>
>
> If guest does not use piggybacking acks, it will send a independent=20
> packet for ack.
> we will get this packet.
> like:
> pkt(seq=3Dxxxx,ack=3Dxxx,flag=3DACK).=20

Right, so looks like if guest want to send some data too, it can send=20
tcp packet without ACK set?