Subject: [ipwave] Iotdir early review of draft-ietf-ipwave-ipv6-over-80211ocb-34

From: Pascal Thubert <[email-masked]>
Date: Mon, 04 Mar 2019 03:26:06 -0800

Reviewer: Pascal Thubert
Review result: Not Ready

Reviewer: Pascal Thubert
Review result: Not ready. Need to clarify IEEE relationship, IOW which SDO
defines the use of L2 fields, what this spec enforces vs. recognizes as being
used that way based on IEEE work. The use of IPv6 ND requires a lot more
thoughts, recommendation to use 6LoWPAN ND. The definition of a subnet is
unclear. It seems that RSUs would have prefixes but that is not discussed.

I am an assigned INT and IOT directorates reviewer for <
draft-ietf-ipwave-ipv6-over-80211ocb-34 >. These comments were written
primarily for the benefit of the Internet Area Directors. Document editors and
shepherd(s) should treat these comments just like they would treat comments
from any other IETF contributors and resolve them along with any other Last
Call comments that have been received. For more details on the INT Directorate,
see https://datatracker.ietf.org/group/intdir/about/

Majors issues
-----------------

“

o  Exceptions due to different operation of IPv6 network layer on
      802.11 than on Ethernet.

“
Is this doc scoped to OCB or 802.11 in general? Is there an expectation that an
implementer of IPv6 over Wi-Fi refers to this doc? Spelled as above, it seems
that you are defining the LLC. Figure 1 shows the proposed adaptation layer as
IEEE LLC work. Who defines those fields, IETF or IEEE, or mixed? Who defines
their use? If this spec defines a new LLC header (vs. how to use an IEEE field)
 then it should be very clear, and the newly defined fields should be isolated
from IEEE fields.

"
   The IPv6 packet transmitted on 802.11-OCB MUST be immediately
   preceded by a Logical Link Control (LLC) header and an 802.11 header.

"
Is there anything new or specific to OCB vs. classical 802.11 operations?
If/when this is echoing the IEEE specs then this text should not use uppercase
but say something like: 'Per IEEE Std 802.11, the IPv6 packet transmitted on
802.11-OCB is immediately  preceded by a Logical Link Control (LLC) header and
an 802.11 header ...'

different things? Why define both?

"   An 'adaptation' layer is inserted between a MAC layer and the
   Networking layer.  This is used to transform some parameters between
   their form expected by the IP stack and the form provided by the MAC
   layer.
"
Is this different from what an AP does when it bridges Wi-Fi to Ethernet? Is
this IETF business?

"
   The Receiver and Transmitter Address fields in the 802.11 header MUST
   contain the same values as the Destination and the Source Address
   fields in the Ethernet II Header, respectively.
"
Same,  this is IEEE game isn't it?

"

Solutions for these problems SHOULD
   consider the OCB mode of operation.
"
This is not specific enough to be actionable. I suggest to remove this sentence.
It would be of interest for the people defining those solutions to understand
the specific needs of OCB vs. Wi Fi, but I do not see text about that.

"

The method of forming IIDs
   described in section 4 of [RFC2464] MAY be used during transition
   time.
"
Contradicts section 4.3 that says
"
Among these types of
   addresses only the IPv6 link-local addresses MAY be formed using an
   EUI-64 identifier.
"

"

This
   subnet MUST use at least the link-local prefix fe80::/10 and the
   interfaces MUST be assigned IPv6 addresses of type link-local.
"
If this is conforming IPv6 then the MUST is not needed.

"
   A subnet is formed by the external 802.11-OCB interfaces of vehicles
   that are in close range (not by their in-vehicle interfaces).
"
Is the definition transitive? Do we really get a subnet?
 A is close to  B who is close to C .... to Z, makes Paris one subnet! Are you
 talking about a link, rather?

"
   The Neighbor Discovery protocol (ND) [RFC4861] MUST be used over
   802.11-OCB links.
"

IPv6 ND is not suited for a non-broadcast network. How does DAD work?
Maybe you could consider RFC 6775 / RFC 8505 instead.

"
In the moment the MAC address is changed
   on an 802.11-OCB interface all the Interface Identifiers of IPv6
   addresses assigned to that interface MUST change.
"
Why is that? This is unexpected, and hopefully wrong.

Minor issues
---------------

"   OCB (outside the context of a basic service set - BSS): A mode of
   operation in which a STA is not a member of a BSS and does not
   utilize IEEE Std 802.11 authentication, association, or data
   confidentiality.

   802.11-OCB: mode specified in IEEE Std 802.11-2016 when the MIB
   attribute dot11OCBActivited is true.  Note: compliance with standards
   and regulations set in different countries when using the 5.9GHz
   frequency band is required.
"

Are these 2 different things?

"
Among these types of
 addresses only the IPv6 link-local addresses MAY be formed using an
  EUI-64 identifier.
"
This text should not be in a LL specific section since it deals with the other
addresses. Maybe rename the section to "addressing" or something?

"
   For privacy, the link-local address MAY be formed according to the
   mechanisms described in Section 5.2.
"
The MAY is not helpful. I suggest to remove the sentence that does not bring
value vs. 5.2

Could you make sections 4.3 and 4.5 contiguous?

"
If semantically
   opaque Interface Identifiers are needed, a potential method for
   generating semantically opaque Interface Identifiers with IPv6
   Stateless Address Autoconfiguration is given in [RFC7217].

   Semantically opaque Interface Identifiers, instead of meaningful
   Interface Identifiers derived from a valid and meaningful MAC address
   ([RFC2464], section 4), MAY be needed in order to avoid certain
   privacy risks.

...

   In order to avoid these risks, opaque Interface Identifiers MAY be
   formed according to rules described in [RFC7217].  These opaque
   Interface Identifiers are formed starting from identifiers different
   than the MAC addresses, and from cryptographically strong material.
   Thus, privacy sensitive information is absent from Interface IDs, and
   it is impossible to calculate the initial value from which the
   Interface ID was calculated.

"
Duplicate and mis ordered text, isn't it?

" For this reason, an attacker may realize many
   attacks on privacy.
"
Do we attack privacy? Maybe say that privacy is a real concern, and maybe move
that text to security section?

"
   The way Interface Identifiers are used MAY involve risks to privacy,
   as described in Section 5.1.
"
Also duplicate

Nits
------

"
   IP packets MUST be transmitted over 802.11-OCB media as QoS Data
   frames whose format is specified in IEEE Std 802.11.
"
Please add link to the reference

" the 802.11 hidden node"
Do not use 802.11 standalone (multiple occurrences).
=> "the IEEE Std. 802.11 [ ref ] hidden node", or just "the hidden terminal".

BCP 14 text:

Suggest to use this text:
“
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   https://tools.ietf.org/html/bcp14 https://tools.ietf.org/html/bcp14
   [https://tools.ietf.org/html/rfc2119][RFC8174] when, and only when, they
   appear in all capitals, as shown here.

“

All the best

Pascal