Stress that PAN ID is not a stable network identifier

Tag: WGLC

Tero Kivinen wrote (https://mailarchive.ietf.org/arch/msg/6tisch/jTAFrLJfp6qfJ3t5UuKBJW3P2RI):

In section 3 there is text saying:

The "network identifier" uniquely identifies the 6TiSCH network in the namespace managed by a JRC. Typically, this is the 16-bit Personal Area Network Identifier (PAN ID) defined in [IEEE802.15.4].

Note, that the PAN ID is not stable. The PAN coordinator is expected to change to use new PAN ID if it detect another network using the same PAN ID, i.e., if there is PAN ID conflict. See section 6.3.2 of the IEEE 802.15.4-2015.

Because of this it might be better to use something else as PAN ID if stable network identifier is needed. Also in quite many cases the PAN ID is not known beforehand, so configuring the PAN ID to the pledge is challenging, as is describied in the section 4.

Using something like Network ID from the draft-richardson-6tisch-enrollment-enhanced-beacon, would provide better alternative.

Good point: we use the term "network_identifier" for precisely this purpose -- allow future extensions where an extended ID from e.g. draft-richardson-6tisch-enrollment-enhanced-beacon can be used. The current text in the draft leaves open what ID is actually used, and as such PAN ID is supported. I wouldn't want to preclude the use of PAN ID now, since this is how most of the people currently deploy their networks.

Would a following resolution work for you:

OLD:

Typically, this is the 16-bit Personal Area Network Identifier (PAN ID) defined in [IEEE802.15.4]. Companion documents can specify the use of a different network identifier for join purposes, but this is out of scope of this specification. Such identifier needs to be carried within Enhanced Beacon (EB) frames.

NEW:

Typically, this is the 16-bit Personal Area Network Identifier (PAN ID) defined in [IEEE802.15.4]. However, PAN ID is not considered a stable network identifier as it may change during network lifetime if a collision with another network is detected. Companion documents can specify the use of a different network identifier for join purposes, but this is out of scope of this specification. Such identifier needs to be carried within Enhanced Beacon (EB) frames.

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