On 09/04/2016 05:07 PM, Xue, Wenqian wrote: > Hi, Alexander > >> -----邮件原件----- >> 发件人: Alexander Aring [mailto:aar@xxxxxxxxxxxxxx] >> 发送时间: 2016年9月1日 23:05 >> 收件人: Xue, Wenqian/薛 文倩 <xuewenqian@xxxxxxxxxxxxxx> >> 抄送: linux-wpan@xxxxxxxxxxxxxxx >> 主题: Re: 答复: 答复: Problems about handling duplicate packets when frame >> retry is enabled >> >> >> Hi, >> >> On 08/20/2016 11:36 PM, Alexander Aring wrote: >>> >>> Hi, >>> >>> On 08/19/2016 03:10 PM, Xue, Wenqian wrote: >>>> Hi, Alexander, >>>> >>>> Sorry for so late reply, as I have some other business at hand. >>>> >>>>> -----邮件原件----- >>>>> 发件人: Alexander Aring [mailto:aar@xxxxxxxxxxxxxx] >>>>> 发送时间: 2016年8月13日 0:29 >>>>> 收件人: Xue, Wenqian/薛 文倩 <xuewenqian@xxxxxxxxxxxxxx> >>>>> 抄送: linux-wpan@xxxxxxxxxxxxxxx >>>>> 主题: Re: 答复: Problems about handling duplicate packets when frame >>>>> retry is enabled >>>>> >>>>> >>> ... >>>>> >>>>> Your modification handles in duplicates in a form which is not >>>>> acceptable. It will simple drop duplicates but how frame retries works is the >> following: >>>> >>>> If your meaning for my modification is that the result will be the same >> whether retry is enabled or not? Initially, my motivation is to prevent the >> received retry packet from being transmitted up to the wpan-ping level, then to >> avoid the error "Sequence number did not match". >>>> >>> >>> I looked deeper for that handling in 802.15.4-2011 (which is the >>> version which is currently free available): >>> >>> 5.1.6.6 Transmission scenarios >>> >>> Your scenario is "Lost acknowledgment frame.", I don't see anything >>> which let me accept your patch to drop multiple received frames with >>> the same sequence number. The receiving node mac802154 stack is >>> "recipient next layer". >>> >>> Or did I miss something? >>> >> >> I see currently 802.11 has some handling which you like to get in. >> See [0]. But I don't see that such handling is described in 802.15.4 :-/ >> >> For me it's clean that it can be that duplicate frames can reach the next layer >> and the next layer need to care about that. That's what "Transmission scenario" >> - "Lost acknowledgment frame" shows me. >> > I also checked the spec when I met the problem first, the spec really does not mention the handling for the duplicates. I thought it could be implemented in reality and should prevent the duplicates to the next layer. If according to your opinion " the next layer need to care about that ", the wpan-ping.c should care about the duplicates, right? Thank you! > I think yes, some upper layers need to care about that or not. Here you have like in "ping6" also a duplicate warning which indicates that you received duplicates and _maybe_ there exists an issue in the lower layers and I think you really should try to detect why you have an lost acknowledgment frame. - Alex -- To unsubscribe from this list: send the line "unsubscribe linux-wpan" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
