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:[email protected]] On Behalf Of Dale R. Worley Sent: 24 November 2016 09:23 To: [email protected]; [email protected] 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 _______________________________________________ 6lo mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lo ------------------------------------------------------------------------------------------------------------------------------- [ C-DAC is on Social-Media too. Kindly follow us at: Facebook: https://www.facebook.com/CDACINDIA & Twitter: @cdacindia ] This e-mail is for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies and the original message. Any unauthorized review, use, disclosure, dissemination, forwarding, printing or copying of this email is strictly prohibited and appropriate legal action will be taken. ------------------------------------------------------------------------------------------------------------------------------- _______________________________________________ 6lo mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lo
