Re: [6tisch] WG adoption of the “IEEE802.15.4 Informational Element encapsulation of 6tisch Join and Enrollment Information” document

[Yasuyuki Tanaka <[e-mail]>]

Hi,

This proposal looks useful. I like the idea of Network ID!

I'm sharing my comments on the draft:

  https://tools.ietf.org/html/draft-richardson-6tisch-enrollment-enhanced-beacon-01

[1] (trivial comment)

draft>   There are a limited number of timeslots designated as a broadcast
draft>   slot by each router.  These slots are rare, and with 10ms slots, with
draft>   a slot-frame length of 100, there may be only 1 slot/s for the
draft>   beacon.

It may be more natural to use a slot-frame length of *101* since RFC
8180 is referred in the beginning of the same section...

[2] RS/RA confusion...?

draft> 1.3.  Layer-3 synchronization IPv6 Router solicitations and
draft>       advertisements
draft> ...
draft>   unsolicited RAs; if a pledge node does not hear an RA, and decides to
draft>   send a RS (consuming a broadcast aloha slot with unencrypted
draft>   traffic), many unicast RS may be sent in response.

The last sentence should be "many unicast RA may be sent in response"?

draft>  2.  it may require many seconds of on-time before a new pledge hears
draft>       a Router Soliciation that it can use.

This also should be "Router Advertisement" instead of "Router
Solicitation"?

draft>   3.  a new pledge may listen to many Enhanced Beacons before it can
draft>       pick an appropriate network and/or closest Join Assistant to
draft>       attach to.  If it must listen for a RS as well as find the
draft>       Enhanced Beacon, then the process may take a very long time.

Same here. s/RS/RA/

[3] (trivial comment)

draft> 2.  Protocol Definition
draft> ...
draft>                         1                   2                   3
draft>     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
draft>    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
draft>    |   TBD-XXX     |R|P| res |  proxy prio |    rank priority      |
draft>    +-+-+-+-+-+-+-+-+-+-------------+-------------+-----------------+
draft> ...
draft>    |               |
draft>    +-+-+-+-+-+-+-+-+
draft> 
draft>    proxy priority  the proxy prority value contains a number from 0 to
draft>       0x7f.  Lower numbers are considered to be a higher preference.  A
draft>       priority of 0x7f indicates that the announcer should never be
draft>       considered as a viable enrollment proxy.  Lower value indicates
draft>       willing to act as a Join Proxy as described in
draft>       [I-D.ietf-6tisch-minimal-security].  Only unenrolled pledges look
draft>       at this value.
draft> 
draft>    pan priority  the pan priority is a value set by the DODAG root to
draft>       indicate the relative priority of this LLN compared to those with
draft>       different PANIDs.  This value may be used as part of the
draft>       enrollment priority, but typically is used by devices which have
draft>       already enrolled, and need to determine which PAN to pick.
draft>       Unenrolled pledges MAY consider this value when selecting a PAN to
draft>       join.  Enrolled devices MAY consider this value when looking for
draft>       an eligible parent device.

It would be easier for readers if the order of the field definitions
is the same as the order the fields appear in the figure.

[4] Proxy Address bit

draft>   P  if the Proxy Address bit is set, then the lower 64-bits of the
draft>      Join Proxy's Link Layer address follows the network ID.

It seems the lower 64-bits of the Join Proxy's Link Layer address *is
followed by* the Network ID in the figure.

draft>       Join Proxy's Link Layer address follows the network ID.  If the
draft>       Proxy Address bit is not set, then the Link Layer address of the
draft>       Join Proxy is identical to the Layer-2 8-byte address used to
draft>       originate this enhanced beacon.

By definition, an Enhanced Beacon cannot have a 2-octet link-layer
address in its source address field? Or, if P bit is set, a
transmitter should set its 8-octet link-layer address to the source
address field of an enhanced beacon?

[5] Join-Proxy Address

draft>    join-proxy lower-64  if the P bit is set, then 64 bits (8 bytes) of
draft>       address are present.  The Link Layer address of the Join Proxy is
draft>       fe80 (as for any Link Layer address), and the bits given in this
draft>       field.

The last sentence is unclear to me... Does it mean that a link-local
IPv6 address of the Join Proxy can be generated by the bits given in
the field with the link-local prefix, fe80::/64?

[6] Network ID

dfaft>    network ID  this is an variable length field, up to 16-bytes in size
dfaft>       that uniquely identifies this network, potentially among many
dfaft>       networks that are operating in the same frequencies in overlapping
dfaft>       physical space.

Can we omit the network ID field?

Best,
Yatch