Re: [6tisch] Early IoT-Dir review of draft-ietf-6tisch-architecture-19

Michael Richardson <> Tue, 19 February 2019 18:56 UTC

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From: Michael Richardson <>
To: iot-dir <>,, Eliot Lear <>
cc:, "Carlos Pignataro \(cpignata\)" <>, CARLOS JESUS BERNARDOS CANO <>
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Date: Tue, 19 Feb 2019 13:56:39 -0500
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Subject: Re: [6tisch] Early IoT-Dir review of draft-ietf-6tisch-architecture-19
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Eliot Lear <> wrote:
    > * I realise you probably didn’t originate the term but Join
    > Registrar/Coordinator (JRC) is an odd acronym. Is this intended to be two
    > architectural components combined into one or just a bit of terminology
    > indecision on the part of the designers ;-)?

In 6tisch the (join) Registrar also is charged with handing out 2-byte
Layer-2/Layer-3 addresses.  802.15.4 has a special layer-2 format when the
MAC address is 2 bytes, and RFC6282 provides for a way to compress layer-3
addresses which are related to l2 addresses.
In other 802.15.4 based networks, L2-address assignment is done by a "Network Coordinator"

Left to itself, 6tisch would call it perhaps the Join Coordinator, but in
order to maintain mindshare with the ANIMA and NETMOD uses of Registrar, it's
a Join Registrar/Coordinator (or JRC).  We went through a consensus call in
all three groups a few years ago to agree on this term.

BRSKI also says

   Join Registrar (and Coordinator):  A representative of the domain
      that is configured, perhaps autonomically, to decide whether a new
      device is allowed to join the domain.  The administrator of the
      domain interfaces with a "join registrar (and coordinator)" to
      control this process.  Typically a join registrar is "inside" its
      domain.  For simplicity this document often refers to this as just
      "registrar".  Within [I-D.ietf-anima-reference-model] this is
      refered to as the "join registrar autonomic service agent".  Other
      communities use the abbreviation "JRC".

Michael Richardson <>ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-