Subject: Re: [lp-wan] New Version Notification for draft-barthel-oam-schc-00.txt

From: Henry-Joseph Audéoud <[email-masked]>
Date: Thu, 1 Aug 2019 16:04:16 +0200

Hi Dominique, hi all,

I read draft-barthel-lpwan-oam-schc-00 after the IETF 105 meeting.  I
have two discussions about the device been ping'ed (section 4.4).

- The SCHC C/D “responds with an Echo Reply on behalf of the Device”.
  Have you considered using e.g. a Code=1 (Proxy Response) while
  replying, to clearly indicate that it's a proxy response, and not the
  real device's one?  This clarifies the situation for the Echo Request
  emitter if it is not aware that the device is inside a LPWAN¹; this
  allows to disambiguate responses in the (still undefined, but
  conceivable) case the Echo Request is really forwarded to the device,
  and the device effectively respond with a standard Code=0 Echo Reply.

  (Type=129 & Code=1 is currently not allocated by the IANA, but
  [RFC4443] envisages that by stating that “The assignment of new Code
  values for the Type values defined in this document require standards
  action or IESG approval.”)

  ¹ Also remember the question of Laurent in the minutes of the
    IETF 105: “can have a message that indicates that's the link is
    LPWAN (useful, security issue?)”

- About the same point, from the minutes of the IETF 105 :

  > Sandra: Question about this scenarios is to be sure that the device
  > is active.
  > 
  > Dominique: good question, this is the base of the discussion, how we
  > want to do it, how much we want to wait for no device activity until
  > we declare it's not there, etc
  > 
  > Laurent: If you see traffic in the last 5 minutes, you respond that
  > the device is active. After that, not.

  It would be really interesting to join the amount of time since last
  seen traffic from this device to the SCHC C/D Echo Reply.  But that's
  not obvious.  The only field (IMHO) in which we might insert this
  information is the data field, but that's not clearly allowed by
  [RFC4443].  It states that “The data received in the ICMPv6 Echo
  Request message MUST be returned entirely and unmodified in the ICMPv6
  Echo Reply message”.  I suppose that this statement also applies if we
  define a new code=1 Proxy Response, isn't is?  And also that, after
  having transmitted the entire and unmodified Echo Request's data, we
  cannot *add* data thereafter, isn't it?

On Mon, Jan 28, 2019 at 11:21:12AM +0000, [email-masked] wrote:
> Dear all,
> 
> We have just posted an update to draft-barthel-icmpv6-schc-00.
> If you have an interest in OAM of IoT devices and ICMPv6, please have a
> look at it and comment back.
> Best regards,
> 
> Dominique 

-- 
Henry-Joseph Audéoud
Univ. Grenoble Alpes - Grenoble INP - LIG