Proxy Mobile IPv6 Extensions for Distributed Mobility Management
draft-ietf-dmm-pmipv6-dlif-06

[Ballot comment]
Thanks for this well-written document!  It is clearly written, and when
multiple approaches exist, does well at laying out the different options
and their pros/cons, as befits an Experimental document.  Also, several
times I have started to write a comment only to realize that it is
answered by the following text :)

[Ballot comment]
Thanks for addressing my discuss and adding section 3.6. I know that the text there is inline with RFC6275 and therefore I'm clearing my discuss. However I just notice that its says

" The node MAY continue to send these
  messages at this slower rate indefinitely."

I think allowing to send something indefinitely is always a bad idea. This is a MAY but given there is no alternative provided, I guess it's not unlikely that people will implement it this way. It's always better to have a defined termination condition. This could be something like "SHOULD stop sending after X  and log an error" where X  is a super high value in e.g. days. This would implicitly also allow to send indefinitely because it's a SHOULD but would make it less likely people implement that. I personal would however even recommend a MUST.

In any case, as RFC6275 has exactly the same sentence, so I'm not blocking on this, but maybe still worth reconsidering...


---------
Old comments: I fully understand why the authors decided to not make changes but keeping these as for the record:


4) As section 3.6 talks mainly about implementation details, I suggest to move this section into the appendix.

7) One overall editorial comment which might be too late to address: I would have found it more easy to read if you would have first introduced the new messages and then used the concrete message names in the description in section 3.

[Ballot comment]
Thank you for the work put into this document. And congratulations for the many advanced ASCII art ! Except for section 3.6, the text is really easy to read.

Thank you also for fixing my previous DISCUSS as well as replying by email to my comments. I have kept the original DISCUSS & COMMENT below.

Please also address the points raised by Carlos during the INT directorate review. Thank you again Carlos !
https://datatracker.ietf.org/doc/review-ietf-dmm-pmipv6-dlif-05-intdir-telechat-pignataro-2020-02-28/

Happy that my comments have helped to improve the document

Regards,

-éric

== OLD DISCUSS ==

-- Section 4.3 & 4.4 & 4.5 --
Probably trivial to fix but is "Prefix Length" expressed in bits (/64) or in bytes (8 bytes). If the latter, then how can we have a prefix of /57 ? The definition of the "Prefix length" field should be specific about the unit (bits/bytes) and be aligned with the definition of "Anchored prefix" (as this one seems to assert that the prefix length must be a multiple of 8).

== COMMENTS ==

A generic question, can a MN be attached to multiple MAAR at the same time? I.e., once over WiFi and once of 3GPP ? There seems to be only one S-MAAR at any time.

-- Section 3.1 --
Should the length of the prefix assigned to the MN be specified? Adding a /64 would make things clearer without using too much of text.

For my own curiosity, the text is about "IPv6 global prefix", but, would ULA also work ?

-- Section 3.6 --
This section is so different than the previous ones in section 3, that I would have created a section on its own.

This section also uses EUI-64 for the link-local address; and, this is no more advised for privacy reason. Not really important in the DMM context though.

Important thing to fix, s/fe80:211:22ff:fe33:101/fe80::211:22ff:fe33:101/ ;-)

The text of this section is really difficult to parse. After 2 readings I am not even sure that I got it... I was about to open a DISCUSS for the point 2) but I am unsure whether I am reading the text correctly.

1) If the MAC and LLA for the 'virtual router' mn1mar2 are different than the one for mn1mar2, why is there a need for different interface? Multiple routers can exist on the same link.

2) For packets sourced by MN1 with prefix1 how can we ensure that they are sent to mn1mar1 and not to mn1mar? PvD could help there and should be mentionned draft-ietf-intarea-provisioning-domains.

-- Section 4.2 --
Bit 31 is not described, it is probably reserved but you should really described it.

With this PBA packet format, all flags / bits are used and assigned for an experimental document. Isn't it a waste of bits? I will really appreciate an answer on this question.


== NITS ==

-- Section 3 (and possibly others) --
The CMD and MAAR acronyms are expanded multiple times. This makes the reading easier for newcomers of course.

[Ballot comment]
I support Mirja Kühlewind's and Ben Kaduk's DISCUSS position.

** Section 6. Per “The CMD SHOULD use a pacing approach to limit this amplification risk”, could you address Vincent Roca’s SECDIR Review (thank you!) question “should that pacing be on the In the incoming queue (i.e., by delaying some PBU/PBA messages) or in the outgoing queue (i.e., to limit output traffic), or both?”

** Section 6.  To provide normative language:
s/This requires security associations to exist between the involved MAARs/
Hence, security associations are REQUIRED to exist between the involved MAARs/

Editorial Nit:
** Section 6. s/there may exist multiple previous (e.g., k) MAARs exist/ there may exist multiple previous (e.g., k) MAARs/

[Ballot discuss]
I have a very boring Discuss point and a somewhat boring point, and
expect to change my ballot to Yes once they're resolved.

In Section 3.2 we say that pacing mechanisms "MAY" be used to avoid
bursts when the CMD is fanning out PBUs, but in Section 6 we say that
pacing "SHOULD" be used; please resolve the inconsistency (preferrably
with "MUST" as Mirja requests).

Please also include some discussion of privacy considerations (I give
some suggestions in the COMMENT).

[Ballot comment]
Thanks for this well-written document!  It is clearly written, and when
multiple approaches exist, does well at laying out the different options
and their pros/cons, as befits an Experimental document.  Also, several
times I have started to write a comment only to realize that it is
answered by the following text :)

Section 1

  The Distributed Mobility Management (DMM) paradigm aims at minimizing
  the impact of currently standardized mobility management solutions
  which are centralized (at least to a considerable extent).

I'd consider saying a little more about which aspects of their operation
are centralized.  Perhaps the following paragraph suffices, though.

  Following this idea, in our proposal, the central anchor is moved to
  the edge of the network, being deployed in the default gateway of the
  mobile node.  That is, the first elements that provide IP

(side note: Using the singular "central anchor" poses an interesting
rhetorical question: is the (formerly) single central anchor being
duplicated and spread amongst all access routers, or does there remain a
single central anchor (per MN), just one that moves around along with
the MN.)

  anchors to retrieve the MN's previous location(s).  Also, a key-
  aspect of network-based DMM, is that a prefix pool belongs
  exclusively to each MAAR, in the sense that those prefixes are
  assigned by the MAAR to the MNs attached to it, and they are routable
  at that MAAR.

It might be worth some statement relating this "ownership" of prefixes
to actual mobility events -- e.g., they are assigned to MNs attached to
it at that time, but remain with those MNs as mobility occurs, but
always remain routable at that MAAR as well as towards the MN itself.

  We consider partially distributed schemes, where the data plane only
  is distributed among access routers similar to MAGs, whereas the

nit: I suggest s/the data plane only/only the data plane/

  control plane is kept centralized towards a cardinal node used as
  information store, but relieved from any route management and MN's
  data forwarding task.

What's the scope of "single" here -- per deployment, per prefix, per
MAAR, ...?

  P-MAAR (Previous MAAR).  When a MN moves to a new point of attachment
      a new MAAR might be allocated as its anchor point for future IPv6
      prefixes.  The MAAR that served the MN prior to new attachment
      becomes the P-MAAR.  It is still the anchor point for the IPv6
      prefixes it had allocated to the MN in the past and serves as the

(side note? Do we expect those previous allocations to eventually "time
out" as sessions using them terminate?  Or are the allocations more
permanent, with intent to reuse if/when the MN returns to that MAAR?)

Section 3

  interest and eventually take the appropriate action.  The procedure
  adopted for the query and the messages exchange sequence might vary
  to optimize the update latency and/or the signaling overhead.  Here

nit: wrong pluralization in "messages exchange sequence"

Section 3.1

  3.  Since this is an initial registration, the CMD stores a permanent
      BCE containing as primary fields the MN-ID, Pref1 and MAAR1's
      address as a Proxy-CoA.

[how permanent is "permanent"?]

Section 3.2

  1.  When the MN moves from its current point of attachment and
      attaches to MAAR2 (now the S-MAAR), MAAR2 reserves another IPv6
      prefix (Pref2), it stores a temporary BCE, and it sends a plain
      PBU to the CMD for registration.

It's not clear to me at this point how MAAR2 has enough information to
determine that this will be a "plain" PBU vs. the the PBU used for
initial registration.  (That said, it's also not clear to me that the
send PBU actually differs on the wire, so maybe this is just a
rhetorical question.  Er, a question of rhetoric, that is.)

  4.  The CMD, after receiving the PBA, updates the BCE populating an
      instance of the P-MAAR list.  The P-MAAR list is an additional
      field on the BCE that contains an element for each P-MAAR
      involved in the MN's mobility session.  The list element contains
      the P-MAAR's global address and the prefix it has delegated (see
      Appendix B for further details).  Also, the CMD sends a PBA to
      the new S-MAAR, containing the previous Proxy-CoA and the prefix
      anchored to it embedded into a new mobility option called
      Previous MAAR Option (defined in Section 4.5), so that, upon PBA
      arrival, a bi-directional tunnel can be established between the
      two MAARs and new routes are set appropriately to recover the IP
      flow(s) carrying Pref1.

To check my understanding: there will only be one Previous MAAR Option
present and it will describe only a single MAAR, which implies that if
there are multiple P-MAARs, traffic directed to an arbitrary prefix
based at one of them is expected to traverse multiple tunnels from
P-MAAR to P-MAAR before making its way to the S-MAAR and the MN?
[Hmm, looks like my understanding is wrong.  I'd consider making
"previous Proxy-CoA" and "the prefix anchored to it" plural to give the
reader a hint as to what's coming, though I can understand if there is
desire to keep the initial mobility example simple and only gradually
introduce the complexity in question.]

  For MN's next movements the process is repeated except the number of
  P-MAARs involved increases (accordingly to the number of prefixes
  that the MN wishes to maintain).  Indeed, once the CMD receives the
  first PBU from the new S-MAAR, it forwards copies of the PBU to all
  the P-MAARs indicated in the BCE as current P-CoA (i.e., the MAAR
  prior to handover) and in the P-MAARs list.  They reply with a PBA to
  the CMD, which aggregates them into a single one to notify the
  S-MAAR, that finally can establish the tunnels with the P-MAARs.

I'm not sure I understand the cardinality of P-CoA -- is it one,
the single S-MAAR prior to handover, or many, all P-MAARs in the list?

  When there are multiple previous MAARs, e.g., k MAARs, a single PBU
  received by the CMD triggers k outgoing packets from a single
  incoming packet.  This may lead to packet bursts originated from the
  CMD, albeit to different targets.  Pacing mechanisms MAY be
  introduced to avoid bursts on the outgoing link.

I'll defer to my TSV colleagues, but a "SHOULD" feels more comfortable
than "MAY" to me, here.

Section 3.3

  The handover latency experienced in the approach shown before can be
  reduced if the P-MAARs are allowed to signal directly their
  information to the new S-MAAR.  This procedure reflects what was
  described in Section 3.2 up to the moment the P-MAAR receives the PBU
  with the P-MAAR option.  At that point a P-MAAR is aware of the new

nit(?): I think this is the S-MAAR option, not the P-MAAR option?

  S-MAAR including the prefix it is anchoring.  This latter PBA does
  not need to include new options, as the prefix is embedded in the HNP
  option and the P-MAAR's address is taken from the message's source
  address.  The CMD is relieved from forwarding the PBA to the S-MAAR,

(side note: this assumes there's no NAT or tunneling or similar between
MAARs, which seems like a plausible assumption, at least for now.)

Section 3.4

  side.  When P-MAARs complete the update, they send a PBA to the CMD
  to indicate that the operation is concluded and the information is
  updated in all network nodes.  This procedure is obtained from the

Is there anything useful to say about behavior on timeout at the CMD
(failing to reive a PBA from one or more P-MAARs)?

Section 3.5

  The de-registration mechanism devised for PMIPv6 cannot be used as is
  in this solution.  The reason for this is that each MAAR handles an

nit: s/as is/as-is/

  Indeed, when a previous MAAR initiates a de-registration procedure,
  because the MN is no longer present on the MAAR's access link, it
  removes the routing state for that (those) prefix(es), that would be
  deleted by the CMD as well, hence defeating any prefix continuity
  attempt.  The simplest approach to overcome this limitation is to

nit(?): s/when/if/.  At least, this makes more sense to me if I do that
... maybe I'm just confused.

  serving MAAR to de-register the whole MN session.  This can be
  achieved by first removing any layer-2 detachment event, so that de-
  registration is triggered only when the session lifetime expires,

I see that RFC 5213 has some mechanisms for lifetime management, but
didn't get to look closely enough to understand how clear the necessary
lifetime management will be in the DMM case when there are multiple
prefixes registered to a given MN at different MAARs.  (Also, 5213
doesn't seem to use the "session lifetime" phrase verbatim.)

Section 3.6

  requiring special support from the mobile node's IP stack.  This
  document defines the Distributed Logical Interface (DLIF), which is a
  software construct that allows to easily hide the change of
  associated anchors from the mobile node.

A software construct in the MAAR, right?


How common is "HMAC" as an abbreviation for "hardware MAC address"?
It's also an abbreviation for Hash-based Message Authentication Code,
which confuses my poor security-focused brain, though I acknowledge that
this does not necessarily extend to most of the target audience for this
document...

  and MN3, while MAAR2 is serving MN1.  MN1, MN2 and MN3 have two
  P-MAARs: MAAR1 and MAAR2.  Note that a serving MAAR always plays the

Do they have two P-MAARs, or one P-MAAR and one S-MAAR (each)?

  role of anchoring MAAR for the attached (served) MNs.  Each MAAR has
  one single physical wireless interface.

Have we defined "anchoring MAAR" yet?
Also, I assume that the "single physical interface" is just "as depicted
in this example" and not a protocol requirement :)

  As introduced before, each MN always "sees" multiple logical routers
  -- one per P-MAAR -- independently of its currently serving MAAR.

[same P-MAAR vs. S-MAAR split as above]

  by the serving MAAR (MAAR2) configuring an additional distributed
  logical interface: mn1mar1, which behaves exactly as the logical
  interface configured by MAAR1 when MN1 was attached to it.  This

nit(?): "exactly" is asking for pedants to try and poke holes in the
claimed perfection.

  deprecated).  The goal is to deprecate the prefixes delegated by
  these MAARs (which will be no longer serving the MN).  Note that on-

nit(?): s/which will be no longer/so that they will no longer be/, IIUC

Section 4.1

The intdir reviewer's comments regarding the flag bits seem apropos (I
presume they were allocated by other extensions to 5213, but we should
say something about it).


  A new flag (D) is included in the Proxy Binding Update to indicate
  that the Proxy Binding Update is coming from a Mobility Anchor and

"D" is for "DMM", I trust?  It could be worth mentioning.

Is the D bit set for the PBUs sent from CMD to P-MAAR as well?
(I see that the PBA description uses a slightly different formulation to
cover the 'D' bit; is there a reason to diverge?)

  Mobility Options

      Variable-length field of such length that the complete Mobility
      Header is an integer multiple of 8 octets long.  This field
      contains zero or more TLV-encoded mobility options.  The encoding
      and format of defined options are described in Section 6.2 of
      [RFC6275].  The MAAR MUST ignore and skip any options that it does
      not understand.

MAARs that *receive* PBUs must be P-MAARs, right?

Section 4.2

  MAAR (D)

      The D is set to indicate that the sender of the message supports
      operating as a Mobility Anchor and Access Router.  When a MAG that
      does not support the extensions described in this document
      receives a message with the D-Flag set, it MUST ignore the message
      and an error MUST be returned.

Is the CMD considered a MAAR for this purpose?

      contains zero or more TLV-encoded mobility options.  The encoding
      and format of defined options are described in Section 6.2 of
      [RFC6275].  The MAAR MUST ignore and skip any options that it does
      not understand.

What about the CMD?

Section 4.3, 4.4

  Prefix Length

      8-bit unsigned integer indicating the prefix length of the IPv6
      prefix contained in the option.

  Anchored Prefix

      A sixteen-byte field containing the mobile node's IPv6 Anchored
      Prefix.  Only the first Prefix Length bytes are valid for the
      Anchored Prefix.  The rest of the bytes MUST be ignored.

Is the prefix length bits or bytes?

Section 4.4

Is this also used to convey "local" prefixes in the PBA from CMD to
S-MAAR?  (If not, how does the S-MAAR know to advertise them from its
DLIF?)

Section 4.5

What's the alignment requirement?
(There's no need to put in a Reserved octet to keep things word
aligned?)

  Prefix Length

      8-bit unsigned integer indicating the prefix length of the IPv6
      prefix contained in the option.
  [...]
  Home Network Prefix

      A sixteen-byte field containing the mobile node's IPv6 Home
      Network Prefix.  Only the first Prefix Length bytes are valid for
      the mobile node's IPv6 Home Network Prefix.  The rest of the bytes
      MUST be ignored.

[is the prefix length bits or bytes?]

Section 4.6

Is there an alignment requirement for this option?

  This new option is defined for use with the Proxy Binding Update and
  Proxy Binding Acknowledgement messages exchanged between the CMD and

When is this option used in a PBA?

Section 4.7

  A new DLIF Link-local Address option is defined for use with the
  Proxy Binding Update and Proxy Binding Acknowledgment messages
  exchanged between MAARs.  This option is used for exchanging the

MAARs but not CMDs?
When is this used in the PBU?

Section 4.8

  A new DLIF Link-layer Address option is defined for use with the
  Proxy Binding Update and Proxy Binding Acknowledgment messages
  exchanged between MAARs.  This option is used for exchanging the

MAARs but not CMDs?
When is this used in the PBU?

Section 6

Unfortunately it seems that RFC 5213 does not include any privacy
considerations discussion.  While the privacy properties of this
protocol bear similarities to those of RFC 5213, it seems that there are
also some significant differences, so I do think it is important to
produce some documentation of privacy considerations for this document.
The main factor would, of cousre, be tracking which entities obtain
updates/information about the location of the MN, what those entities
are expected to do with that data, and how trusted they are to be proper
custodians of it.  Other factors may exist as well, including the
potential for side-channel information leakage, e.g., due to traffic
analysis.  There might also be a reverse situation where exposing the
link-layer address(es) of a P-MAAR have privacy considerations, though I
don't have anything particular in mind at the moment.

  security concerns of Proxy Mobile IPv6 [RFC5213].  It is recommended
  that the signaling messages, Proxy Binding Update and Proxy Binding
  Acknowledgment, exchanged between the MAARs are protected using IPsec
  using the established security association between them.  This

This is essentially unchanged from 5213, just with different names for
the endpoints, right, and so the existing guidance/experiences apply?

I think we should also say something about all MAARs and the CMD being
trusted parties.  We should also say something about the authorization
model (I assume it's just "all trusted parties are trusted to perform
all operations relevant to their role", but that's still useful to say).

  When the CMD acts as a PBU/PBA relay, the CMD may act as a relay of a
  single PBU to multiple previous MAARs.  In situations of many fast
  handovers (e.g., with vehicular networks), there may exist multiple
  previous (e.g., k) MAARs exist.  In this situation, the CMD creates k

nit: remove the redundant "exist"

  When the CMD acts as MAAR locator, mobility signaling (PBAs) is
  exchanged between P-MAARs and current S-MAAR.  This requires security
  associations to exist between the involved MAARs (in addition to the
  ones needed with the CMD).

Is this relevant because of scaling/resource-consumption concerns or
keying/trust ones?

Appendix A.5

  not implement existing mobility protocols.  Furthermore, a DMM
  solution SHOULD work across different networks, possibly operated as
  separate administrative domains, when the needed mobility management

Hmm, separate administrative domains makes the risk of NAT relatively
higher (per previous comment about NAT).

  intervention.  The partially distributed DMM solution can be deployed
  across different domains with trust agreements if the CMDs of the
  operators are enabled to transfer context from one node to another.

It would probably be worth expounding a bit more about this scenario and
the necessary trust/authorization relationships, in the security
considerations.

[Ballot comment]
Thanks for the work on this document. I have only one editorial suggestion.

Section 3.6:

>  to-point link) with MN1, exposing itself as a (logical) router with a
>  specific MAC (e.g., 00:11:22:33:01:01) and IPv6 addresses (e.g.,

Please use a MAC address from the range reserved for documentation purposes by section 2.1.1 of RFC 7042.

[Ballot discuss]
Thank you for the work put into this document. And congratulations for the many advanced ASCII art ! Except for section 3.6, the text is really easy to read.

I have a block DISCUSS below but it should be trivial to fix.

Please also address the points raised by Carlos during the INT directorate review. Thank you again Carlos !
https://datatracker.ietf.org/doc/review-ietf-dmm-pmipv6-dlif-05-intdir-telechat-pignataro-2020-02-28/

I hope that this helps to improve the document,

Regards,

-éric

== DISCUSS ==

-- Section 4.3 & 4.4 & 4.5 --
Probably trivial to fix but is "Prefix Length" expressed in bits (/64) or in bytes (8 bytes). If the latter, then how can we have a prefix of /57 ? The definition of the "Prefix length" field should be specific about the unit (bits/bytes) and be aligned with the definition of "Anchored prefix" (as this one seems to assert that the prefix length must be a multiple of 8).

[Ballot comment]
== COMMENTS ==

A generic question, can a MN be attached to multiple MAAR at the same time? I.e., once over WiFi and once of 3GPP ? There seems to be only one S-MAAR at any time.

-- Section 3.1 --
Should the length of the prefix assigned to the MN be specified? Adding a /64 would make things clearer without using too much of text.

For my own curiosity, the text is about "IPv6 global prefix", but, would ULA also work ?

-- Section 3.6 --
This section is so different than the previous ones in section 3, that I would have created a section on its own.

This section also uses EUI-64 for the link-local address; and, this is no more advised for privacy reason. Not really important in the DMM context though.

Important thing to fix, s/fe80:211:22ff:fe33:101/fe80::211:22ff:fe33:101/ ;-)

The text of this section is really difficult to parse. After 2 readings I am not even sure that I got it... I was about to open a DISCUSS for the point 2) but I am unsure whether I am reading the text correctly.

1) If the MAC and LLA for the 'virtual router' mn1mar2 are different than the one for mn1mar2, why is there a need for different interface? Multiple routers can exist on the same link.

2) For packets sourced by MN1 with prefix1 how can we ensure that they are sent to mn1mar1 and not to mn1mar? PvD could help there and should be mentionned draft-ietf-intarea-provisioning-domains.

-- Section 4.2 --
Bit 31 is not described, it is probably reserved but you should really described it.

With this PBA packet format, all flags / bits are used and assigned for an experimental document. Isn't it a waste of bits? I will really appreciate an answer on this question.


== NITS ==

-- Section 3 (and possibly others) --
The CMD and MAAR acronyms are expanded multiple times. This makes the reading easier for newcomers of course.

[Ballot discuss]
Sec 3.2:
"The INITIAL_BINDACK_TIMEOUT [RFC6275] SHOULD
  be used for configuring the retransmission timer."
Use of this timeout from RFC6275 is fine. However, you should also indicate that the rest of the specified retransmission mechanism should be used as well. That means exponential backoff as well as a max number of retries. Further I think it would also be important to overall rate-limit the traffic e.g. as specified in RFC6275:
"The mobile node MUST NOT send Mobility Header messages
  of a particular type to a particular correspondent node more than
  MAX_UPDATE_RATE times within a second."

In addition the same mechanisms should probably be also required for any (new) message sent by the P/S-MAAR in other modes.

Finally in the security consideration section I see this:
"The CMD SHOULD use a pacing approach to limit
  this amplification risk."
Which is good! But why is that a SHOULD and not a MUST?

Update: This discuss is inline with the comments provided by the TSV-ART review (thanks Jörg!) which lead to an update that don't seem fully addressed. So please review that feedback as well and continue discussion with the TSV-ART reviewer if needed.

[Ballot discuss]
Sec 3.2:
"The INITIAL_BINDACK_TIMEOUT [RFC6275] SHOULD
  be used for configuring the retransmission timer."
Use of this timeout from RFC6275 is fine. However, you should also indicate that the rest of the specified retransmission mechanism should be used as well. That means exponential backoff as well as a max number of retries. Further I think it would also be important to overall rate-limit the traffic e.g. as specified in RFC6275:
"The mobile node MUST NOT send Mobility Header messages
  of a particular type to a particular correspondent node more than
  MAX_UPDATE_RATE times within a second."

In addition the same mechanisms should probably be also required for any (new) message sent by the P/S-MAAR in other modes.

Finally in the security consideration section I see this:
"The CMD SHOULD use a pacing approach to limit
  this amplification risk."
Which is good! But why is that a SHOULD and not a MUST?

[Ballot discuss]
Sec 3.2:
"The INITIAL_BINDACK_TIMEOUT [RFC6275] SHOULD
  be used for configuring the retransmission timer."
Use of this timeout from RFC6275 is fine. However, you should also indicate that the rest of the specified retransmission mechanism should be used as well. That means exponential backoff as well as a max number of retries. Further I think it would also be important to overall rate-limit the traffic e.g. as specified in RFC6275:
"The mobile node MUST NOT send Mobility Header messages
  of a particular type to a particular correspondent node more than
  MAX_UPDATE_RATE times within a second."

In addition the same mechanisms should probably be also required for any (new) message send by the P/S-MAAR in other modes.

Finally in the security consideration section I see this:
"The CMD SHOULD use a pacing approach to limit
  this amplification risk."
Which is good! But why is that a SHOULD and not a MUST?

[Ballot discuss]
Sec 3.2:
"The INITIAL_BINDACK_TIMEOUT [RFC6275] SHOULD
  be used for configuring the retransmission timer."
Use of this timeout from RFC6275 is fine. However, you should also indicate that the rest of the specified retransmission mechanism should be used as well. That means exponential backoff as well as a max number of retries. Further I think it would also be important to overall rate-limit the traffic e.g. as specified in RFC6275:
"The mobile node MUST NOT send Mobility Header messages
  of a particular type to a particular correspondent node more than
  MAX_UPDATE_RATE times within a second."

In addition the same mechanisms should probably be also required for any (new) message send by the P/S-MAAR in other modes.

Finally on in the security consideration section I see this:
"The CMD SHOULD use a pacing approach to limit
  this amplification risk."
Which is good! But why is that a SHOULD and not a MUST?

[Ballot comment]
Editorial comments/nits:

1)Sec 1: "Following this idea, in our proposal, the central anchor is..."
Maybe remove "in our proposal" as this is not a proposal only anymore when published.

2) Sec 2:
"The following terms used in this document are defined in the DMM
  Deployment Models and Architectural Considerations document
  [I-D.ietf-dmm-deployment-models]:"
As there doesn't seem to be any plan to actually publish draft-ietf-dmm-deployment-models anymore, maybe move the respective definitions into this document.

3) Sec 3: "Note that a MN MAY move across different MAARs"
This should be lower case "may".

4) As section 3.6 talks mainly about implementation details, I suggest to move this section into the appendix.

5) In the appendix you always talk about "our solution". This is rather uncommon for an RFC. I recommend to chance to e.g. "the solution specified in this document".

6) Are both appendices A and B are still needed?

7) One overall editorial comment which might be too late to address: I would have found it more easy to read if you would have first introduced the new messages and then used the concrete message names in the description in section 3.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

Write-up for draft-ietf-dmm-pmipv6-dlif-05

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

Experimental. This is appropriate given the experimental nature of the work.


(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:


Technical Summary

This document describes a new mechanism for realizing distributed mobility management system based on Proxy Mobile IPv6 protocol. 


Working Group Summary

This document has been in development, first as an individual submission in the DMM WG and later as a working group document.
The document has gone through around 5 revisions.

Document Quality

The document is well-written  and technically correct in our opinion. The document  had some amount of reviews and inputs by the working group and also by some of the mobility experts in the WG. Furthermore, some of the authors have very good understanding of the Proxy Mobile IPv6 protocol and therefore we believe the quality of the document is good.

Personnel

Dapeng(Max) Liu is the document shepherd.
Suresh Krishnan is the current responsible AD.


(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

I read the document, understood the content and have also discussed with the authors. I believe this version of the document is ready for publication.


(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

This document has been reviewed by experts that active in DMM working group.


(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

As this document’s focus is on Proxy Mobile IPv6 protocol, and is a product of DMM WG, we tend to think the reviews from the WG are sufficient.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

The document describes a useful extension and is well-written.  We do not have any concerns forwarding this document to IESG for reviews.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

Yes.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

The following IPR disclosures were made against this document.

https://datatracker.ietf.org/ipr/3477/
https://datatracker.ietf.org/ipr/3478/
https://datatracker.ietf.org/ipr/1724/


WG is aware of this disclosure, but no one in the WG has expressed any concerns.



(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

There is rough consensus behind this document and no objections have
been raised.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

There are no issues reported by the tool. All the reported issues have been addressed in the prior versions.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

N/A


(13) Have all references within this document been identified as
either normative or informative?

Yes

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

No


(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

No

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

This document defines some new flags to the Proxy Mobile IPv6 defined PBU and PBA messages. The impacted registries and the actions are identified in the IANA section of the document.

(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

There are no new registries defined.

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

This document does not use formal language.

(Via drafts-lastcall@iana.org): IESG/Authors/WG Chairs:

The IANA Functions Operator has completed its review of draft-ietf-dmm-pmipv6-dlif-04. If any part of this review is inaccurate, please let us know.

The IANA Functions Operator understands that, upon approval of this document, there is a single action which we must complete.

In the Mobility Options registry on the Mobile IPv6 parameters registry page located at:

https://www.iana.org/assignments/mobility-parameters/

six, new mobility options are to be registered as follows:

Value: [ TBD-at-Registration ]
Description: Anchored Prefix Option
Reference: [ RFC-to-be ]

Value: [ TBD-at-Registration ]
Description: Local Prefix Option
Reference: [ RFC-to-be ]

Value: [ TBD-at-Registration ]
Description: Previous MAAR Option
Reference: [ RFC-to-be ]

Value: [ TBD-at-Registration ]
Description: Serving MAAR Option
Reference: [ RFC-to-be ]

Value: [ TBD-at-Registration ]
Description: DLIF Link-local Address Option
Reference: [ RFC-to-be ]

Value: [ TBD-at-Registration ]
Description: DLIF Link-layer Address Option
Reference: [ RFC-to-be ]

The IANA Functions Operator understands that this is the only action required to be completed upon approval of this document.

Note:  The actions requested in this document will not be completed until the document has been approved for publication as an RFC. This message is meant only to confirm the list of actions that will be performed.

Thank you,

Sabrina Tanamal
Senior IANA Services Specialist

The following Last Call announcement was sent out (ends 2019-10-14):

From: The IESG
To: IETF-Announce
CC: draft-ietf-dmm-pmipv6-dlif@ietf.org, max.ldp@alibaba-inc.com, dmm-chairs@ietf.org, dmm@ietf.org, Dapeng Liu , suresh@kaloom.com
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Proxy Mobile IPv6 extensions for Distributed Mobility Management) to Experimental RFC


The IESG has received a request from the Distributed Mobility Management WG
(dmm) to consider the following document: - 'Proxy Mobile IPv6 extensions for
Distributed Mobility Management'
  as Experimental RFC

The IESG plans to make a decision in the next few weeks, and solicits final
comments on this action. Please send substantive comments to the
ietf@ietf.org mailing lists by 2019-10-14. Exceptionally, comments may be
sent to iesg@ietf.org instead. In either case, please retain the beginning of
the Subject line to allow automated sorting.

Abstract


  Distributed Mobility Management solutions allow for setting up
  networks so that traffic is distributed in an optimal way and does
  not rely on centrally deployed anchors to provide IP mobility
  support.

  There are many different approaches to address Distributed Mobility
  Management, as for example extending network-based mobility protocols
  (like Proxy Mobile IPv6), or client-based mobility protocols (like
  Mobile IPv6), among others.  This document follows the former
  approach and proposes a solution based on Proxy Mobile IPv6 in which
  mobility sessions are anchored at the last IP hop router (called
  mobility anchor and access router).  The mobility anchor and access
  router is an enhanced access router which is also able to operate as
  a local mobility anchor or mobility access gateway, on a per prefix
  basis.  The document focuses on the required extensions to
  effectively support simultaneously anchoring several flows at
  different distributed gateways.





The file can be obtained via
https://datatracker.ietf.org/doc/draft-ietf-dmm-pmipv6-dlif/

IESG discussion can be tracked via
https://datatracker.ietf.org/doc/draft-ietf-dmm-pmipv6-dlif/ballot/

The following IPR Declarations may be related to this I-D:

  https://datatracker.ietf.org/ipr/1724/
  https://datatracker.ietf.org/ipr/3477/
  https://datatracker.ietf.org/ipr/3478/

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

1) The type of RFC being requested is Experimental.
2) This document describes experimental solution of proxy mobile IP extensions to support distributed mobility management.
3) The type of RFC is indicated in the title page header.

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

    This document defines proxy mobile IP extension to support distributed mobility management.

Working Group Summary

This document has been reviewed and agreed by the working group.


Document Quality

The solution describes in this document has been implemented by DEMOs.


Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Shepherd: Dapeng(Max) Liu
Responsible Area Director: Suresh Krishnan

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

This document specifies proxy mobile IP extension to support distributed mobility management. This version of the document is ready for publication.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

This document has been reviewed by experts that active in DMM working group.


(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

No.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

N/A.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

Yes.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

There is 3 IPR disclosure references to this document:
https://datatracker.ietf.org/ipr/3030/

Working group discussion and conclusion:

[TBD]

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

This document has reached consensus in the working group and there is no objection to move forward.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

Idnits has been checked, issues found has been solved.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

No.


(13) Have all references within this document been identified as
either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

No.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

No.

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

This document defines new mobility options for proxy mobile IP that require IANA to have new registry and those request have been described in the document.


(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

N/A

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

This document does not use formal language.

As required by RFC 4858, this is the current template for the Document
Shepherd Write-Up.

Changes are expected over time. This version is dated 24 February 2012.

(1) What type of RFC is being requested (BCP, Proposed Standard,
Internet Standard, Informational, Experimental, or Historic)?  Why
is this the proper type of RFC?  Is this type of RFC indicated in the
title page header?

1) The type of RFC being requested is Experimental.
2) This document describes experimental solution of proxy mobile IP extensions to support distributed mobility management.
3) The type of RFC is indicated in the title page header.

(2) The IESG approval announcement includes a Document Announcement
Write-Up. Please provide such a Document Announcement Write-Up. Recent
examples can be found in the "Action" announcements for approved
documents. The approval announcement contains the following sections:

Technical Summary

    This document defines proxy mobile IP extension to support distributed mobility management.

Working Group Summary

This document has been reviewed and agreed by the working group.


Document Quality

The solution describes in this document has been implemented by DEMOs.


Personnel

  Who is the Document Shepherd? Who is the Responsible Area
  Director?

Shepherd: Dapeng(Max) Liu
Responsible Area Director: Suresh Krishnan

(3) Briefly describe the review of this document that was performed by
the Document Shepherd.  If this version of the document is not ready
for publication, please explain why the document is being forwarded to
the IESG.

This document specifies proxy mobile IP extension to support distributed mobility management. This version of the document is ready for publication.

(4) Does the document Shepherd have any concerns about the depth or
breadth of the reviews that have been performed?

This document has been reviewed by experts that active in DMM working group.


(5) Do portions of the document need review from a particular or from
broader perspective, e.g., security, operational complexity, AAA, DNS,
DHCP, XML, or internationalization? If so, describe the review that
took place.

No.

(6) Describe any specific concerns or issues that the Document Shepherd
has with this document that the Responsible Area Director and/or the
IESG should be aware of? For example, perhaps he or she is uncomfortable
with certain parts of the document, or has concerns whether there really
is a need for it. In any event, if the WG has discussed those issues and
has indicated that it still wishes to advance the document, detail those
concerns here.

N/A.

(7) Has each author confirmed that any and all appropriate IPR
disclosures required for full conformance with the provisions of BCP 78
and BCP 79 have already been filed. If not, explain why.

Yes.

(8) Has an IPR disclosure been filed that references this document?
If so, summarize any WG discussion and conclusion regarding the IPR
disclosures.

There is 3 IPR disclosure references to this document:
https://datatracker.ietf.org/ipr/3030/

Working group discussion and conclusion:

[TBD]

(9) How solid is the WG consensus behind this document? Does it
represent the strong concurrence of a few individuals, with others
being silent, or does the WG as a whole understand and agree with it? 

This document has reached consensus in the working group and there is no objection to move forward.

(10) Has anyone threatened an appeal or otherwise indicated extreme
discontent? If so, please summarise the areas of conflict in separate
email messages to the Responsible Area Director. (It should be in a
separate email because this questionnaire is publicly available.)

No.

(11) Identify any ID nits the Document Shepherd has found in this
document. (See https://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

Idnits has been checked, issues found has been solved.

(12) Describe how the document meets any required formal review
criteria, such as the MIB Doctor, media type, and URI type reviews.

No.


(13) Have all references within this document been identified as
either normative or informative?

Yes.

(14) Are there normative references to documents that are not ready for
advancement or are otherwise in an unclear state? If such normative
references exist, what is the plan for their completion?

No.

(15) Are there downward normative references references (see RFC 3967)?
If so, list these downward references to support the Area Director in
the Last Call procedure.

No.

(16) Will publication of this document change the status of any
existing RFCs? Are those RFCs listed on the title page header, listed
in the abstract, and discussed in the introduction? If the RFCs are not
listed in the Abstract and Introduction, explain why, and point to the
part of the document where the relationship of this document to the
other RFCs is discussed. If this information is not in the document,
explain why the WG considers it unnecessary.

No.

(17) Describe the Document Shepherd's review of the IANA considerations
section, especially with regard to its consistency with the body of the
document. Confirm that all protocol extensions that the document makes
are associated with the appropriate reservations in IANA registries.
Confirm that any referenced IANA registries have been clearly
identified. Confirm that newly created IANA registries include a
detailed specification of the initial contents for the registry, that
allocations procedures for future registrations are defined, and a
reasonable name for the new registry has been suggested (see RFC 5226).

This document defines new mobility options for proxy mobile IP that require IANA to have new registry and those request have been described in the document.


(18) List any new IANA registries that require Expert Review for future
allocations. Provide any public guidance that the IESG would find
useful in selecting the IANA Experts for these new registries.

N/A

(19) Describe reviews and automated checks performed by the Document
Shepherd to validate sections of the document written in a formal
language, such as XML code, BNF rules, MIB definitions, etc.

This document does not use formal language.

Request for posting confirmation emailed to previous authors: Antonio de la Oliva , Carlos Bernardos , Fabio Giust , dmm-chairs@ietf.org, Alain Mourad , Juan Zuniga