Re: [ipwave] Intdir early review of draft-ietf-ipwave-ipv6-over-80211ocb-34

["Pascal Thubert (pthubert)" <[e-mail]>]

Hello Carlos

I think we’re a bit stuck.

 I spent really a long time explaining why RFC 4861 does not cut it by itself. No magic will make that happen. I tried to help by indicating a version of ND that was designed for radios and to my best knowledge will work here. I understand that people will not trust that on “face value” but I do not understand that people prefer something that was designed before the concept of a radio link was even considered and is known not to work.

In any fashion I cannot support a doc that lets the outside of the IETF believe that RFC 4861 is suited for OCB. RFC 4861 survives on BSS thanks to the association process that provides a signal for DNA and emulates an Ethernet broadcast domain. Nothing like that on OCB.

Best can do is send the doc back to the WG till it can provide a satisfactory solution to ND.

Regards,

Pascal

Le 9 avr. 2019 à 03:04, CARLOS JESUS BERNARDOS CANO <[e-mail]<mailto:[e-mail]>> a écrit :

Hi Pascal, all,

Sorry to jump late into this discussion.

Thanks for the provided text.

I think it contains good parts that I'd recommend authors to consider incorporating into the draft. I see you are already discussing about that and I hope the WG reaches an agreement on how to modify current text.

I have some comments from my side:

- I tend to agree with Alex in that I'd skip the RECOMMENDED part of the text (referring to RFC 8505). I agree that some pieces of RFC 8505 could be adapted to be used in OCB, but I think using RECOMMENDED with further analysis within the WG is too much. I'd rather prefer that RFC 8505 is referenced in the draft as a solution that could be used as starting point to enhance ND over OCB (but we have agreed already in the WG that ND enhacements are outside the scope of current draft).

- I see good points in Pascal's text, but probably need some language fixing, as it might lead to some questions as the Alex has pointed out.

- I'd appreciate if we all acknowledge here all the work Alex (and the rest of the authors) have been doing so far, as well as Pascal's help. Please, try to keep the discussion positive. That _always_ helps.

Thanks,

Carlos

On Fri, Apr 5, 2019 at 5:09 PM Pascal Thubert (pthubert) <[e-mail]<mailto:[e-mail]>> wrote:
Dear all;

As promised I put together some words on using IPv6 ND and then RFC 8505 for OCB. Please find attached early text. This could become a section 4.7.
Note that RFC 8505 enables a DAD operation for both link local and global addresses, the associated global prefix being owned by either a car or a RSU. RSUs connected to the internet can advertise a default router preference to indicate they are willing to relay packets for global addresses.
The attached text impacts other sections in particular the discussion on global addresses which is somehow avoided in the current draft and could be reintroduced.

Comments welcome : )

Pascal

From: Pascal Thubert (pthubert)
Sent: jeudi 28 mars 2019 11:29
To: Alexandre Petrescu <[e-mail]<mailto:[e-mail]>>
Cc: [e-mail]<mailto:[e-mail]>
Subject: Re: Intdir early review of draft-ietf-ipwave-ipv6-over-80211ocb-34

Yes Alex. Also as an offer to help...

Regards,

Pascal

Le 28 mars 2019 à 11:08, Alexandre Petrescu <[e-mail]<mailto:[e-mail]>> a écrit :

Pascal,

Should we treat these two reviews (iotdir and intdir reviews) as just one?

The contents appear to me to be the same.

Alex
Le 04/03/2019 à 12:24, Pascal Thubert a écrit :

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