Re: [6tsch] set DAGRank to Join Priority

Hi Qin,

my suggestion is to use JoinPriority[5:0] = (rank[15:8]&0x3F) or 0x3F if
bigger -- having a 0x3F would be like having INFINITE Join Priority as in
the case of RPL with ranks>65535.

would that not work?
X

On Fri, Sep 27, 2013 at 1:44 PM, Qin Wang <qinwang@berkeley.edu> wrote:

> Xavi,
>
> Let's take the example in your draft to see what the problem is. Please
> point out if I'm wrong.
> +-------+
>      |   0   | R(0)=0
>      |       | DAGRank(R(0)) = 0
>      +-------+
>          |
>          |
>      +-------+
>      |   1   | R(1)=R(0)+683=683
>      |       | DAGRank(R(1)) = 2
>      +-------+
>          |
>          |
>      +-------+
>      |   2   | R(2)=R(1)+683=1366
>      |       | DAGRank(R(2)) = 5
>      +-------+
>          |
>          |
>      +-------+
>      |   3   | R(3)=R(2)+683=2049
>      |       | DAGRank(R(3)) = 8
>      +-------+
>          |
>          |
>      +-------+
>      |   4   | R(4)=R(3)+683=2732
>      |       | DAGRank(R(4)) = 10
>      +-------+
>          |
>          |
>      +-------+
>      |   5   | R(5)=R(4)+683=3415
>      |       | DAGRank(R(5)) = 13
>      +-------+
>
> From the example, you can see R(n) is a 2-byte integer, and DAGRank is
> always the higher byte of the 2byte integer, because minHopRankIncrease =
> 256.
>
> If set JoinPriority = DAGRank, then it is possible JoinPriority> 0x3f
> (although it unlikely happens often), out of its range.
> If set JoinPriority[5:0] = DAGRank[7:2], (Is it your suggestion?), a new
> node may found many existing nodes with same JoinPriority in received EB.
> In another word, the JoinPriority can not provide information about
> preferring joining. Right?
>
> I haven't had good solution for it. So, I hope the range 0x00~0x3f is not
> a "MUST" in IEEE802.15.4e.
>
> What  do you think?
> Qin
>
>
>
>
> On Sat, Sep 28, 2013 at 2:30 AM, Xavier Vilajosana Guillen <
> xvilajosana@eecs.berkeley.edu> wrote:
>
>> Hi Qin,
>>
>> after thinking a little bit on that maybe we can use the higher byte of
>> the rank for that. that is  rank>>8, the higher byte is a monotonically
>> increasing counter. As each hop is <<8 (due to minhopRankIncrease) we can
>> have the sense of higher join priority as higher the rank.
>>
>> In addition having if we have the limitation of 0x3F, this means that we
>> will support Join priorities up to 0x3F that translated to ranks are
>> 0x3F<<8 (big number) ..
>>
>> just thoughts...
>> X
>>
>>
>> On Fri, Sep 27, 2013 at 10:30 AM, Qin Wang <qinwang@berkeley.edu> wrote:
>>
>>> Hi Thomas,
>>>
>>> I think with OF0 the DAGRank is uint8. But, in the Table 52b of
>>> IEEE802.15.4e, the range of Join Priority is 0x00~0x3f. If the range is a
>>> "MUST", we have to have a function mapping a DAGRank in 0x00~0xff to a
>>> JoinPriority in 0x00~0x3f. Correct?
>>>
>>> Would you please confirm with some expertise in IEEE802.15.4e if the
>>> range 0x00~0x3f is a MUST or not?
>>>
>>> Thanks
>>> Qin
>>>
>>> _______________________________________________
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>>> 6tsch@ietf.org
>>> https://www.ietf.org/mailman/listinfo/6tsch
>>>
>>>
>>
>