[Roll] Liaison from ITU-T SG15 to ROLL and 6Lo

[Ines Robles <[e-mail]>]

Dear all,

We would like to have your opinion before this friday (24 July) about 
this liaison "ITU-T SG15 liaison to ROLL and 6Lo".

Many Thanks,

Michael and Ines.

Source: https://datatracker.ietf.org/liaison/1415/

ITU-T Study Group 15 has been designated as the lead study group for

communications-related aspects of Smart Grid. Question 15 (Q15/15) is

responsible for Recommendations ITU-T G.9903 (Narrow-band OFDM power line

communication transceivers for G3-PLC networks – approved in 02/2014) and

ITU-T G.9905 (Centralized Metric based Source Routing – approved in 
07/2013).

These two Recommendations normatively reference 6loWPAN (RFC 4944) and its

header compression mechanism (RFC6282).

We would like to bring to your attention that on-going discussion in 
IETF 6lo

and ROLL WGs on reusing the ESC and MESH dispatch headers for route-over and

mixed operations may lead IETF to deprecate the possibility of using RFC4944

and/or RFC6282 in pure mesh-under networks. This deprecation would create a

conflict with Recommendation ITU-T G.9903 and possibly also other 
standards.

Below we give details on how ITU-T G.9903 uses the ESC and MESH dispatch

headers, confirming how important the stability of the 6LoWPAN standard and

related IANA allocations are for ITU-T G.9903:

1.      ITU-T G.9903 provides native mesh-under functionalities (the LOADng

protocol, which is described in Annex D) while not prohibiting the use of

other mesh-under (e.g. CMSR specified in ITU-T G.9905) or route-over routing

protocols. If other routing protocols are used, then the native mesh-under

LOADng protocol can be disabled.

a.      The first octet corresponds to the ESC Dispatch Header as 
specified in RFC

6282, i.e. 0b10 000 000.

b.      The second octet corresponds to the command ID. As specified in 
Table

9-35/G.9903, three possible commands are currently specified (additional

commands can be specified to support other routing protocols):

i.      o LOADng command frame

ii.     o loWPAN bootstrapping command frame

iii.    o CMSR command frame (see ITU-T G.9905).

c.      The rest of the frame carries the payload for the relevant 
command frame.

2.      The ESC Dispatch Header is used by ITU-T G.9903 exclusively for 
command

frames. A command frame is built as follows (see Figure 9-12/ G.9903):

3.      During the bootstrapping phase, the 6LOWPAN_IPHC and ESC headers are

present in the same frame. The ESC dispatch header is placed after the

6LOWPAN_IPHC header.

4.      The MESH Header as specified in RFC 4944 is used for data frames 
only and

contains vital information for the correct delivery of G.9903 data 
frames when

the mesh-under LOADng routing protocol is used.

As of today, Japan and France have already started deployment of ITU-T 
G.9903

smart meters (in France smart meters will represent a total of 32 million

ITU-T G.9903 smart meters – 100% national coverage − by 2021). There are 
also

deployed wireless technologies for smart metering (e.g., based on 802.15.4)

that support layer 2 mesh routing as well. Furthermore, interest in such

technologies transcends smart metering applications and includes a 
broader set

of Smart Grid applications and beyond, making ITU-T G.9903 an important

enabler also for IoT applications.

As several existing standards/products rely on using the Dispatch ESC Header

for exchanging mesh-under routing and bootstrapping command messages, we 
would

like to bring to your attention that deprecating this feature would have

detrimental effects on Smart Grid plans of several countries and utilities:

•       Planned deployments would have to be delayed until a viable 
alternative is

found, standardized, and tested in the field. This would make several

utilities in the world inevitably incur high costs.

•       Future deployments based on the above alternative would be 
non-interoperable

with the currently installed base of devices that rely on the 
availability of

the Dispatch ESC Header.

•       Any delay would put at risk complying with deadlines set by 
regulators of

several countries. One notable example is the 2008 Directive from the 
European

Union which mandates EU countries to deploy 80% of smart meters by 2020.

ITU encourages IETF to:

•       Avoid deprecation of the ESC and MESH dispatch headers and look for

alternative solutions that do not create conflict with existing 
standards and

products.

•       Work in cooperation with Q15/15 to find alternate solutions that 
do not

create conflicts with ITU-T Recommendations.

Q15/15 looks forward to continued cooperation with IETF.