Re: [6lo] IETF 97 : Comments : draft-lijo-6lo-expiration-time-00.txt

Hi

Can anyone recommend me a draft where routing issues are discussed in 6lo?
I am working on link metrics for routing in low-power networks and it will
help me to align my research according to some standard.

Looking forward for the reply

Regards
Sajjad

On Fri, Nov 25, 2016 at 5:17 AM, Lijo Thomas <lijo@cdac.in> wrote:

> Hi Dale,
>
> Thanks for your valuable suggestion !!!
>
> The explanation is perfect for the packets whose Source and Destination are
> within the same network(For example., same 6TiSCH network).When a packet
> traverses from heterogeneous networks then "Time in microseconds" is the
> natural way to represent it.
>
> We can think of designing "slot time" approach from Leaf node to LBR and
> convert it into "Time(micro-seconds)" at the gateway node. But, again the
> issue is we will be having Time mismatch during the conversion from
> slot-time to "microseconds".
>
> We will certainly work on the idea you suggested so that we can come up
> with
> a proposition without compromising on the generality.
>
>
> Thanks & Regards,
> Lijo Thomas
>
>
> -----Original Message-----
> From: 6lo [mailto:6lo-bounces@ietf.org] On Behalf Of Dale R. Worley
> Sent: 24 November 2016 09:23
> To: lijo@cdac.in; 6lo@ietf.org
> Subject: Re: [6lo] IETF 97 : Comments :
> draft-lijo-6lo-expiration-time-00.txt
>
> To me, it would be natural to specify an expiration time as the
> time-to-expiration, measured in slot times.
> draft-lijo-6lo-expiration-time-00 specifies expiration time as an absolute
> time, measured from ASN=0 in microseconds.  The latter approach seems to
> require larger headers, without making processing much simpler.
>
> It seems to me that measuring expriation time in microseconds is no more
> useful than measuring it in slot times, because there is no functional
> difference between any of the 10,000 microseconds within a single 10 ms
> slot
> time.  But counting microseconds requires an additional 13 bits (over 1.5
> octets) in the header.
>
> Specifying time-to-expiration means that every time the packet is
> forwarded,
> the expiration header must be updated.  But it can make the expiration
> header shorter.  For instance, in the example I mentioned in my previous
> message,
>
>    Example: In a 6TiSCH network let the time-slot length be 10ms.  If
>    the network has been operational for 2 years, the
>    packet_origination_time = Current ASN is 6,307,200,000, and the
>    max_allowable_delay is 1 second, then:
>
>       expiration_time = packet_origination_time + max_allowable_delay
>                       = 6,307,200,000*10 ms + 1 second
>                       = 63,072,001,000,000 microseconds
>
> or
>
>       expiration_time = ASN 6,307,200,100
>
> Expressing the absolute expiration time in slot times requires 33 bits/5
> octets.  But the time-to-expiration is only 100 and can be expressed in
> 7 bits/1 octet.
>
> Dale
>
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