Minutes for LWIG at IETF-96

Meeting Minutes Light-Weight Implementation Guidance (lwig) WG
Title Minutes for LWIG at IETF-96
State Active
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Last updated 2016-08-01

Meeting Minutes

   LWIg @IETF 96
12:20-13:20     Friday Afternoon session I
Room: Schoeneberg
Berlin Intercontinental

 * Minute takers: Rahul
 * Jabber Scribe: Renzo Navas

  1. Agenda bashing 5 min

Zhen: presenting the agenda

 2. TCP over Constrained Nodes    Carles Gomez Montenegro
    https://tools.ietf.org/html/draft-gomez-core-tcp-constrained-node 20 min
    slides: https://www.ietf.org/proceedings/96/slides/slides-96-lwig-1.pdf

Carles: TCP over constrained node networks
TCP will be used in IoT networks ... TCP has not recevd much attention...
Goal is to offer simple TCP measures for IoT networks
Explains CNN characteristics (RFC 7228)
Recommendations about using TCP over CNN... possible recommendations in the
form of TCP MSS. Recommended use of one window size Performance evaluation of
CoCoA mentioned ,  recommending use of CoCoA recommendations on the keep-alive
mechanism .. Consider use of TCP fast open .. Need some detailed anylsis ...
Cookie is included in the pkt increasing the msg size ... needs detailed
analysis. ECN can be used to trigger congestion control mechanism earlier ...
Options in TCP which would not impact in such cases (LLN cases)... SACK may be
a relevant option.

For future revisions, major scenario to consider is constrained node talking to
non-constrained node. It will be great to know implementation experiences ..

[Carsten]: its good thing to have doc like this .. doc could be little be more
explicit about asymmetric implementations ... anything a less constrained
implemetnation can do to help non-constrained impleemteations. we often forget,
that another IoT protocol used is XMPP .. Oleg: draft about tcp compression...
have the authors checked out this draft ?? [Carles]: had seen the draft, but
several years old .. it would be nice to have tcp compression Oleg: TCP
implementation as part of RIOT in progress kerry: Nodes have to be able to
assemble mtu of 1500 .. pls dont limit to certain implementation ... TCP
implementation already in contiki Michael: as TCPM WG co-chair.  Interesting
doc on how to implement. fail to see any value in changing the tcp spec in this
wg. any change to tcp has to be taken up in appropriate in TCPM wg Suresh:
Slide 12 doesnt belong here ... If WG decides to adopt the doc .. then the
review has to be done from tcp group .. . Further discussion on ML... [zhen]
agree with Michael on TCPM wg synchonization

3. Implementation experiences of public-key cryptography on 8-bit
micro-controllers  Mohit Sethi
    https://tools.ietf.org/html/draft-aks-lwig-crypto-sensors-01  15 min

small devices of 8b uprocessing, 2-5kb ram ...
performance undesireable with RSA .. signing with private key was pretty slow..
ECDSA implementation considered were for 8b uprocessors..
In <3KB RAM, you can do signing operation is less than a second..
shows numbers for signing and verification for 8b uprocessor...
shows an eg app scenario .. details about the topology and configuration ..

Can get quite minimal implementation with some efforts..
Cost is more to turn on/off the radio than the crypto operations!!
Tradeoffs discussions ... misconception that sym crypto doesnt scale .. for low
latency consider using object security .. ll2 security has problems .. because
they use group keys usually .. Need to ensure freshness, to avoid replay
attacks ... some guidelines on the same in the draft.

Authors believe its fairly stable ..
[Juan]: what kind of radio interfaces were used ?
[mohit]: mostly ethernet based interfaces ... no radio..
** About a dozen people have read the draft ...
[raghavendra]: found useful for the thesis
** More than > 20 people think that the doc can be adopted ...
** No one against the adoption.

4. Minimal ESP   Tobias Guggemos (Started 13h00)
    https://tools.ietf.org/html/draft-mglt-lwig-minimal-esp  10 min
explains context to use IPSEC based security...
Problems with DTLS, app layer security ... highlights privacy issues...
with ipsec on the gateway, the ip addresses of end devices not sent..
IPSEc also capable of multicast security and any other transport layer protocol
.. explains flexibility of IPSEC, any key exchange protocol can be used .. Goal
of minimal esp is provide guidelines to implemnent IPsec for IOT networks...
explains ESP packet format. .. explains use of the fields .. SPI, Seq Num,
padding recommendations ... IPSec is a valuable option for IOT.. [suresh]: have
we got any comments on the draft yes, Tero is involved .. [brian]: havent
really cut any bytes ... no compression involved .. only implementation
guidelines .. no compression included [suresh]: if the wg decides to adopt,
suresh will help to get additional review done.. [zhen]: what's the difference
of this draft with two other 6lo drafts. [daniel]: explains difference between
diet ESP and this guideliness .. [zhen]: is any implemetation present? started
implementation on contiki ...

*** 6/7 people have read the draft..
Go on the list to check the consensus .. and hope to get reviews from security
folks ..

5. Lwig terminology update discussion  Carsten Bormann
    https://tools.ietf.org/html/RFC7228   10 min
checks in room who knows rfc 7228 ?
explains the need to update the rfc 7228 ..
terminology needed to distinguish ucontrollers..
Two more classes to be used for distinguishing ..
category based on crytpo supported, protection capabilities (secure storage,
tamper-proof etc ) [Renzo]: On ACE we are facing problems related to clock
capabilities (real time -wallclock-, relative time, no clock at all, ..)  OAuth
 uses timestamp for token validations but some devices might not have. ... need
clear defntion of clock capabilities, to  clearlystate the problem, then define
solutions. would like to assemble a group of people who can contribute ...
[kerry]: extremely useful work ,, people think raspberry pi as constrained
device .. not enough awareness on the power constraints ... [chistian]: note
that there is work going on on tranport negotiation [ana miraburo]: (LPWAN) new
scale of bytes transreception (talking about lpwan networks, very few
payload/bandwith). TOn lpwan the thorughpout scale is one order of magnitude
different from seconds to day [emmanuel]: support this work .. two phases in
the doc to asses what is changed and then reduce the number of classes ..
[suresh]: rfc is the right format for this ?? something which is evolving ..
rfc 7228 is too young to be obsoleted.. wg should consider this point ..
[carsten]: content needs consensus, so at least wg draft is a needed format,
not wiki [zhen]: call for contribution .. [suresh]: can go for consensus
without the draft