Re: [DNA] Review of draft-ietf-dna-link-information-03.txt

[Jari Arkko <jari.arkko@kolumbus.fi>]

FWIW, I agree with most of Bernard's comments. Some further
discussion below:

> a. The document appears to apply to both IPv4 and IPv6, but it makes a
> number of statements that do not reflect the operation of DNAv4 as
> defined in RFC 4436.  For example, DNAv4 does not utilize "link down"
> events or make use of link layer "hints".

> This abstract does not clearly indicate the purpose of the document.  It
> would be helpful to state that the primary purpose is to address
> events relating to DNAv6 (since the document does not appear to apply to
> DNAv4). 

If we take a strict interpretation of the charter, the DNA WG is
only chartered to look at IPv6. Having said that, a version
agnostic document would in my opinion be useful, assuming
we could make it acceptable. I'm not sure why there would
be a need for the v4 and v6 case to differ much, since *this*
document should not describe the actual DNA process -- just
input for the process, such as the "link up" event.

Also, I can not see where the "link down" event is used
even in DNAv6 -- draft-ietf-dna-protocol uses "link up"
only, just as DNAv4. But is it used somewhere else? If
not, perhaps the right thing to do is to focus only on the
"link up" in this document.

>
> "  BSSID and SSID MUST be provided as auxiliary information
>    along with the link up notification.  Unfortunately this information
>    does not provide a deterministic indication of whether the IP-layer
>    configuration MUST be changed upon movement."
>
> Given the limitations of the BSSID and SSID, why the
> normative language?  DNAv4 implementations will not use this
> information.

I agree that the BSSID and SSID may be of limited value. If they
are needed, at least MUST seems inappropriate.

> "   Link-Layer indications in Ethernet-like networks are complicated by
>    additional unadvertised delays due to Spanning Tree calculations.
>    This may cause re-indication (link up with A-flag) or retraction
>    (link up with B-flag) of indications previously sent to upper layer
>    protocols."
>
> What are the A and B flags?  Is this an artifact of a previous revision?

Defined earlier in Section 2.

Anyway, I have a question for you Bernard: draft-iab-link-indications
talks about the importance of damping and hysterisis -- has that
been sufficiently addressed in the wireless parts of the
dna-link-information document?

--Jari