Telechat Review of draft-ietf-dmm-best-practices-gap-analysis-08
review-ietf-dmm-best-practices-gap-analysis-08-genart-telechat-davies-2014-11-28-00

Hi, Anthony.

These changes look good.  I have run through all the changes in -08 and

there are (IMO) a couple of minor nits left:

s3, two instances paras after bullet #3 [2nd cut!]:
OLD

   the Forwarding Management (FM) function resides in both ends of the

tunnel

   between the HA and the MN.  [MAG in second case]

NEW:

   the Forwarding Management (FM) function is distributed between the

ends of the tunnel

   between the HA and the MN.  [MAG in second case]

[Missed this one in -07]

s4.2, 2nd para after Figure 1: s/Two kind/Two kinds/

s4.2, 3rd para after Figure 1: "flattening mobile networks" -- this

piece of jargon could do with a definition or at least a pointer to a

reference.

s4.2.1, para 2, last sentence: s/in IETF/in IETF standards/ [or "documents"]

Figure 2: Still needs a (small) key to indicate "==== <- tunnel"
Similarly for Figures 3 and 4.

s4.2.1, 2nd para after Figure 3:
s/some form of route optimization/a form of route optimization/

s4.2.1, 4th para after Figure 3:
s/used to help distributing/used to help with distributing/

s5.2, GAP2-3: The para formatting doesn't match the other GAPs.

On 11/10/14 06:16, H Anthony Chan wrote:

Elwyn,
Thank you for your review. We have revised and uploaded version -08 with
the following changes:
Applicability to Mobile IPv4?  It appears from the early sections that
this draft is pretty much concentrated on Mobile IPv6 (see the first
para of s3 which mentions v6 RFCs exclusively and IPv4 seems to be
mentioned in only a very limited way later) although this is not
stated.  To avoid wasting people's time, it would be useful to put a few
words about the relevance or otherwise of this draft to Mobile IPv4 work
in the introduction (and maybe the title?) before we get to s5.3 where
there is more clarity.
The following is appended to the end of first paragraph in the introduction:

The analysis is primarily
towards IPv6 deployment, but can be seen to also apply to IPv4
whenever there are IPv4 counterparts equivalent to the IPv6 mobility
protocols.

s6:  I don't know if there is any extra security risk in adding extra
MAs etc that might allow a malicious party to offer spurious MA and so
to redirect traffic inappropriately.  I don't know enough about this
problem space to know how well this is mitigated already.  Might be
worth a mention? (maybe would affect s5.8 if so).
The first sentence in Section 6 in version -07 was

6.Security Considerations

Distributed mobility management systems encounter same security

threats as existing centralized IP mobility protocols.

It is changed in version -08 to:

6.Security Considerations

The deployment of DMM using existing IP mobility protocols raises
similar security threats as those encountered in centralized mobility
management systems.

It is no longer referring to DMM systems in general.
s1: For the uninitiated, a explanation of what a mobility anchor is
would be helpful.  Quoting some (or even all) of the first para of RFC
7333 would do the trick nicely.
The first paragraph is changed to:

1.Introduction

Existing network-layer mobility management protocols have primarily
employed a mobility anchor to ensure connectivity of a mobile node by
forwarding packets destined to, or sent from, the mobile node after
the node has moved to a different network.The mobility anchor has
been centrally deployed in the sense that the traffic of millions of
mobile nodes in an operator network is typically managed by the same
anchor.This centralized deployment of mobility anchors to manage IP
sessions poses several problems.In order to address these problems,
a distributed mobility management (DMM) architecture has been
proposed.This document investigates whether it is feasible to
deploy current IP mobility protocols in a DMM scenario in a way that
can fulfill the requirements as defined in [RFC7333].It discusses
current deployment practices of existing mobility protocols and
identifies the limitations (gaps) in these practices from the
standpoint of satisfying DMM requirements.The analysis is primarily
towards IPv6 deployment, but can be seen to also apply to IPv4
whenever there are IPv4 counterparts equivalent to the IPv6 mobility
protocols.

s1, para 1: s/pose several problems/poses several problems/
changed as suggested

s2, last para: s/without the reliance on centrally deployed/without
reliance on centrally deployed/
changed to

without relying on centrally deployed mobility anchors to manage
IP mobility sessions.

s3, para 1:

Although these two are centralized approaches,

Two? Three items are mentioned in the previous sentence, but maybe the
Host approach and Proxy extension is supposed to be considered as a
single scheme.  Maybe something like:
       "Although these approaches are centralized,.."
would avoid the confusion.
changed as suggested

s3, two instances paras after bullet #3:
OLD

    the
    forwarding management (FM)function is both ends of tunneling at the
    HA and the MN. [MAG in second case]
NEW:
    the forwarding management (FM) function involves both ends of the tunnel
    between the HA and the MN.  [MAG in second case]

changed to:

the
Forwarding Management (FM) function resides in both ends of the
tunnel at the HA and the MN.

s3, last para: s/MAP also has FM function/MAP also provides the FM function/

corrected

s4.2, para after Figure 1: Probably best to s/In the figure/In Figure 1/ just
to be totally clear.

corrected

s4.2, 2nd para after Figure 1:

    IP mobility protocols can be used to provide inter-access mobility
    support to users

I don't know if 'inter-access mobility' is acceptable jargon but I would suggest
adding 'mode', 'method' or 'technology' -- thus

IP mobility protocols can be used to provide inter-access mode mobility
    support to users

changed to

IP mobility protocols can be used to provide heterogeneous network
mobility support to users, e.g., handover from Wi-Fi to cellular
access.

s4.2.1, para 2:

Note
    that some of these mechanisms [SDO-3GPP.23.402  <

http://tools.ietf.org/html/draft-ietf-dmm-best-practices-gap-analysis-07#ref-SDO-3GPP.23.402

>] have been defined in
    other standards organizations.

It is not clear what 'some' refers to here:  It could refer to the mechanisms
that are noted as not specified [implied, by the IETF?] or someting earlier in
the paragraph or stuff in Figure 2 (BT/RO modes?).  Please clarify.

Sentenced is deleted

Figure 2:  I like the 'zzzz' :-) I guess this is supposed to signify a tunnel
but it would be appropriate to have a key for '(o)' and 'zzzz'!  I take it
CN1/CN2 are 'Correspondent Nodes' (per section 2) but it might be useful to
reinforce this in the key also.

Figure 2 is redrawn

s4.2.1, para after bullets: Please expand acronym CoA on first use.

Corrected

s4.2.1, para before Fig 3: s/It allows reducing the amount/It allows the
reduction of the amount/

Corrected

Figure 4: Oh, dear! Boring old 'xxx' for tunnels. :-(  But I guess it should
have a key again.

Figure 4 is redrawn

s4.2.2, para after Fig 4: s/Similar to/In a similar way to/

Corrected

s4.2.2, 2nd para after Fig 4: s/the LMA runtime assignment [RFC6463]/the support
the LMA runtime assignment described in [RFC6463  <

http://tools.ietf.org/html/rfc6463

>]/;

Corrected

s/is mainly aimed for/is mainly aimed at/

will change in version 09 to"is mainly used for"

s4.3, para 1: Is there a suitable overview reference for the EPS architecture? 
Might be useful here.

added reference  [SDO-3GPP.23.402]

s4.3, para before Fig 6:

... or at the macro, ...

I have no idea what this means.

deleted these words
Figures 6 and 7: Something has gone wrong with the layout here.
(Non-ASCII characters?)
corrected
s4.3, Figure 7 and para before it (and earlier): I think PGW and P-GW,
also SGW and S-GW, are supposed to be acronyms for the same thing.
Please make this consistent. (PGW is used elsewhere as well).
changed to PGW
s4.3, para after Fig 7: I think eNB needs expansion [Thank you 3GPP for
the heavy duty acronym soup!]
defined acronym for enhanced Node B
Figure 8: Is "H(e)NB" the same as "HeNB"? Be good to be consistent if
so; If not what is the difference?
Changed to
HeNB
s4.3, last para: s/specially/especially/
corrected
s5, general: Indexing the gaps:  For the purposes of clarity, future
discussion and possible solutions, it would probably be worth assigning
serial numbers to the identified gaps  in the same way as the
requirements are indexed (maybe even linking them to the relevant req by
calling gaps related to REQ#0 something like GAP#0-1, GAP#0-2 etc.)
There are also a couple of places, notably the end of s5.2, where it is
not quite clear whether items (like the last para of s5.2) are separate
gaps or part of the previous one. Numbering the gaps might help to
concentrate the text on linking together (or separating) problems into
well-defined sets.
s5.1, para 1: s/enable/make it possible for/; s/single/a single/
corrected
s5.1, first bullet: s/this may also require to transfer/this may also
require the transfer of/
corrected
s5.1, para after 2nd bullet: s/therefore providing/thereby providing/
corrected
s5.1, 2nd para after 2nd bullet:
OLD: where the mobility client natively knows each anchor associated to
each mobility sessions.
NEW: where the mobility client natively knows the anchor associated with
each of its mobility sessions.
corrected
s5.1, 3rd para after 2nd bullet: s/to allow dynamically discovering the
presence of nodes/to allow the dynamic discovery of the presence of nodes/;
corrected
s/to allow selecting a node/to allow the selection of a node/
will change in version 09
and...OLD: There are though some mechanisms that could help discovering
anchors, such as the Dynamic Home Agent Address Discovery (DHAAD)NEW:
However, there are some mechanisms that could help to discover anchors,
such as the Dynamic Home Agent Address Discovery (DHAAD)
changed
Additionally:
Does DHAAD deserve a reference?
added reference [RFC6275]
s5.1, last para: I have suggested some changes to make this clearer (I
hope):
OLD: Also note that REQ1 is such that the data plane traffic can avoid
suboptimal route. Distributed processing of the traffic is then needed
only in the data plane. The needed capability in distributed processing
therefore should not contradict with centralized control plane. Other
control plane solutions such as charging, lawful interception, etc.
should not be limited. Yet combining the control plane and data plane
forwarding management (FM) function may limit the choice to distributing
both data plane and control plane together. In order to enable
distributing only the data plane without distributing the control plane,
a gap is to split the forwarding management function into the control
plane (FM-CP) and data plane (FM-DP).
NEW: Also note that REQ1 is intended to prevent the data plane traffic
taking a suboptimal route. Distributed processing of the traffic is
then, hopefully, needed only in the data plane. Provision of this
capability for distributed processing should not conflict with the use
of a centralized control plane. Other control plane solutions such as
charging, lawful interception, etc. should not be constrained by the DMM
solution. On the other hand combining the control plane and data plane
forwarding management (FM) function may limit the choice of solutions to
those that distribute both data plane and control plane together. In
order to enable distribution of only the data plane without distributing
the control plane,it would be necessary to split the forwarding
management function into control plane (FM-CP) and data plane (FM-DP)
components; there is currently a gap here.
changed to

GAP1-4:Also note that REQ1 is intended to prevent the data plane
traffic from taking a suboptimal route.Distributed
processing of the traffic may then be needed only in the
data plane.Provision of this capability for distributed
processing should not conflict with the use of a centralized
control plane.Other control plane solutions such as
charging, lawful interception, etc.should not be
constrained by the DMM solution.On the other hand
combining the control plane and data plane forwarding
management (FM) function may limit the choice of solutions
to those that distribute both data plane and control plane
together.In order to enable distribution of only the data
plane without distributing the control plane, it would be
necessary to split the forwarding management function into
the control plane (FM-CP) and data plane (FM-DP) components;
there is currently a gap here.

s5.2, para 1: s/flexibility on determining/flexibility in determining/;
s/whether or not use/whether or not to use/
changed
s5.2, para 1:

  It only enables the two following functions:

I am not sure what 'it' refers to here. Is this the functionality that
is needed to implement REQ1? Or what?
Changed to:

The following two functions are also
needed:

s5.2, 1st bullet: s/which uses/which use/
corrected
s5,2, 1st para after bullets: s/to indicate the IP stack/to indicate to
the IP stack/
corrected
s5,2, 1st para after bullets:

mobility support is required or not in.

Either the 'in' is redundant or there is a phrase missing at the end.
delete
"in"
s5.2, next to last para: s/there exist these individual efforts
that/these individual efforts and they/
changed to

Although these individual efforts exist and they could be
considered as attempts to fix the gap, there is no solution
adopted as a work item within any IETF working group.

s5.4, para 2: s/nothing prevent/nothing prevents/;
corrected
s/functions with in IP mobility/functions within IP mobility/
corrected
s5.4, last para: s/going into the direction/going in the direction/
corrected
s5.5: s/the needed mobility management/the necessary mobility management/
corrected
s5.6, bullet 6: s/of forwarding path/of the forwarding path/
corrected
s5.6, para after bullets: s/the above list of operation/how, or whether,
they support the above list of operation/

corrected

s5.7: Everything after the first sentence is either 'motherhood and apple pie'
or statements
  of things that allegedly work.  No gaps are identified - so everything except
  the first sentence
could probably be replaced with:
    Any solutions that are intended to fill in gaps identified in this document
    need to meet this requirement.  At present, it does not appear that using
    existing solutions to support DMM has introduced any new security issues.

added as suggested

s5.8, para 1: s/to enable multicast solutions to be developed/to allow the
development of multicast solutions/

corrected

s5.8, para 2: s/insta ces/instances/

corrected

Section 5.9 is revised to

5.9.Summary

We next list the main gaps identified from the analysis performed
above:

GAP1-1:Existing solutions only provide an optimal initial anchor
assignment, a gap being the lack of dynamic anchor change/
new anchor assignment.Neither the HA switch nor the LMA
runtime assignment allows changing the anchor during an
ongoing session.MOBIKE allows change of GW but its
applicability has been scoped to a very narrow use case.

GAP1-2:The MN needs to be able to perform source address selection.
Proper mechanism to inform the MN is lacking to provide the
basis for the proper selection.

GAP1-3:Currently, there is no efficient mechanism specified by the
IETF that allows the dynamic discovery of the presence of
nodes that can play the role of anchor, discover their
capabilities and allow the selection of the most suitable
one.However, the following mechanisms could help
discovering anchors:

Dynamic Home Agent Address Discovery (DHAAD): the use of the
home agent (H) flag in Router Advertisements (which
indicates that the router sending the Router Advertisement
is also functioning as a Mobile IPv6 home agent on the link)
and the MAP option in Router Advertisements defined by
HMIPv6.

GAP1-4:While existing network-based DMM practices may allow the
deployment of multiple LMAs and dynamically select the best

one, this requires to still keep some centralization in the
control plane, to access the policy database (as defined in
RFC5213).Although [I-D.ietf-netext-pmip-cp-up-separation]
allows a MAG to perform splitting of its control and user
planes, there is a lack of solutions/extensions that support
a clear control and data plane separation for IETF IP
mobility protocols in a DMM context.

GAP2-1:The information of which sessions at the mobile node are
active and are using the mobility support need to be
transferred to or shared with the network.Such mechanism
has not been defined.

GAP2-2:The mobile node needs to simultaneously use multiple IP
addresses with different properties.There is a lack of
mechanism to expose this information to the mobile node
which can then update accordingly its source address
selection mechanism.

GAP2-3:The handling of mobility management has not been to the
granularity of an individual session of a user/device
before.The combination of session identification and user/
device identification may be lacking.

GAP6-1:Mobility management protocols have not thoroughly documented
how, or whether, they support the following list of
operation and management considerations:

*A DMM solution needs to consider configuring a device,
monitoring the current operational state of a device,
responding to events that impact the device, possibly by
modifying the configuration and storing the data in a
format that can be analyzed later.

*A DMM solution has to describe in what environment and
how it can be scalably deployed and managed.

*A DMM solution has to support mechanisms to test if the
DMM solution is working properly.

*A DMM solution is expected to expose the operational
state of DMM to the administrators of the DMM entities.

*A DMM solution, which supports flow mobility, is also
expected to support means to correlate the flow routing
policies and the observed forwarding actions.

*A DMM solution is expected to support mechanisms to check
the liveness of the forwarding path.

*A DMM solution has to provide fault management and
monitoring mechanisms to manage situations where update
of the mobility session or the data path fails.

*A DMM solution is expected to be able to monitor the
usage of the DMM protocol.

*DMM solutions have to support standardized configuration
with NETCONF [RFC6241], using YANG [RFC6020] modules,
which are expected to be created for DMM when needed for
such configuration.

GAP6-2:Management information base (MIB) objects are currently
defined in [RFC4295] for MIPv6 and in [RFC6475] for PMIPv6.
Standardized configuration with NETCONF [RFC6241], using
YANG [RFC6020] modules is lacking.

s5.9, bullet 1: s/to very narrow use case./to a very narrow use case./

corrected

s5.9, bullet 2: s/requires to expose/requires the exposure of/

The entire sentence is rewritten

There is a lack of
mechanism to expose this information to the mobile node
which can then update accordingly its source address
selection mechanism.

s5.9, bullet 3: s/allows to dynamically discover/allows the dynamic discovery
of/

corrected

s5.9, bullet 5: s/may allow to deploy/may allow the deployment of/

corrected

s6: s/encounter same security/encounter the same security/

Entire sentenced has been rewritten

The deployment of DMM using existing IP mobility protocols raises
similar security threats as those encountered in centralized mobility
management systems.

H Anthony Chan

*From:* Elwyn Davies <

mailto:elwynd

 at dial.pipex.com>
*Sent:* Thursday, September 18, 2014 12:00 PM
*To:* General area reviewing team <

mailto:gen-art

 at ietf.org> ;
draft-ietf-dmm-best-practices-gap-analysis.all at tools.ietf.org
<

mailto:draft-ietf-dmm-best-practices-gap-analysis.all

 at tools.ietf.org>
*Subject:* Gen-art LC review of
draft-ietf-dmm-best-practices-gap-analysis-07

I am the assigned Gen-ART reviewer for this draft. For background on
Gen-ART, please see the FAQ at

<

http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.

Please resolve these comments along with any other Last Call comments
you may receive.

Document: draft-ietf-dmm-best-practices-gap-analysis-07.txt
Reviewer:  Elwyn Davies
Review Date: 2014-09-18
IETF LC End Date: 2014-09-25
IESG Telechat date: (if known) -

Summary:  Almost ready.  A couple of minor issues (one almost editorial
and one may be due to my lack of knowledge of the current state of
Mobile IPv6 security) and mostly a lot of minor language nits.  I think
there might be some point in numbering the identified gaps to facilitate
future discussion.

Major issues:
None

Minor issues:
Applicability to Mobile IPv4?  It appears from the early sections that
this draft is pretty much concentrated on Mobile IPv6 (see the first
para of s3 which mentions v6 RFCs exclusively and IPv4 seems to be
mentioned in only a very limited way later) although this is not stated.
To avoid wasting people's time, it would be useful to put a few words
about the relevance or otherwise of this draft to Mobile IPv4 work in
the introduction (and maybe the title?) before we get to s5.3 where
there is more clarity.

s6:  I don't know if there is any extra security risk in adding extra
MAs etc that might allow a malicious party to offer spurious MA and so
to redirect traffic inappropriately.  I don't know enough about this
problem space to know how well this is mitigated already.  Might be
worth a mention? (maybe would affect s5.8 if so).

Nits/editorial comments:
s1: For the uninitiated, a explanation of what a mobility anchor is
would be helpful.  Quoting some (or even all) of the first para of RFC
7333 would do the trick nicely.

s1, para 1: s/pose several problems/poses several problems/

s2, last para: s/without the reliance on centrally deployed/without
reliance on centrally deployed/

s3, para 1:

Although these two are centralized approaches,

Two? Three items are mentioned in the previous sentence, but maybe the
Host approach and Proxy extension is supposed to be considered as a
single scheme.  Maybe something like:
       "Although these approaches are centralized,.."
would avoid the confusion.

s3, two instances paras after bullet #3:
OLD

    the
    forwarding management (FM)function is both ends of tunneling at the
    HA and the MN. [MAG in second case]
NEW:
    the forwarding management (FM) function involves both ends of the tunnel
    between the HA and the MN.  [MAG in second case]

s3, last para: s/MAP also has FM function/MAP also provides the FM function/

s4.2, para after Figure 1: Probably best to s/In the figure/In Figure 1/ just
to be totally clear.

s4.2, 2nd para after Figure 1:

    IP mobility protocols can be used to provide inter-access mobility
    support to users

I don't know if 'inter-access mobility' is acceptable jargon but I would suggest
adding 'mode', 'method' or 'technology' -- thus

IP mobility protocols can be used to provide inter-access mode mobility
    support to users

s4.2.1, para 2:

Note
    that some of these mechanisms [SDO-3GPP.23.402  <

http://tools.ietf.org/html/draft-ietf-dmm-best-practices-gap-analysis-07#ref-SDO-3GPP.23.402

>] have been defined in
    other standards organizations.

It is not clear what 'some' refers to here:  It could refer to the mechanisms
that are noted as not specified [implied, by the IETF?] or someting earlier in
the paragraph or stuff in Figure 2 (BT/RO modes?).  Please clarify.

Figure 2:  I like the 'zzzz' :-) I guess this is supposed to signify a tunnel
but it would be appropriate to have a key for '(o)' and 'zzzz'!  I take it
CN1/CN2 are 'Correspondent Nodes' (per section 2) but it might be useful to
reinforce this in the key also.

s4.2.1, para after bullets: Please expand acronym CoA on first use.

s4.2.1, para before Fig 3: s/It allows reducing the amount/It allows the
reduction of the amount/

Figure 4: Oh, dear! Boring old 'xxx' for tunnels. :-(  But I guess it should
have a key again.

s4.2.2, para after Fig 4: s/Similar to/In a similar way to/

s4.2.2, 2nd para after Fig 4: s/the LMA runtime assignment [RFC6463]/the support
the LMA runtime assignment described in [RFC6463  <

http://tools.ietf.org/html/rfc6463

>]/; s/is mainly aimed for/is mainly aimed at/

s4.3, para 1: Is there a suitable overview reference for the EPS architecture? 
Might be useful here.

s4.3, para before Fig 6:

... or at the macro, ...

I have no idea what this means.

Figures 6 and 7:  Something has gone wrong with the layout here.  (Non-ASCII
characters?)

s4.3, Figure 7 and para before it (and earlier): I think PGW and P-GW, also SGW
and S-GW, are supposed to be acronyms for the same thing. Please make this
consistent. (PGW is used elsewhere as well).

s4.3, para after Fig 7: I think eNB needs expansion [Thank you 3GPP for the
heavy duty acronym soup!]

Figure 8: Is "H(e)NB" the same as "HeNB"? Be good to be consistent if so; If
not what is the difference?

s4.3, last para: s/specially/especially/

s5, general: Indexing the gaps:  For the purposes of clarity, future discussion
and possible solutions, it would probably be worth assigning serial numbers to
the identified gaps  in the same way as the requirements are indexed (maybe
even linking them to the relevant req by calling gaps related to REQ#0
something like GAP#0-1, GAP#0-2 etc.)  There are also a couple of places,
notably the end of s5.2, where it is not quite clear whether items (like the
last para of s5.2) are separate gaps or part of the previous one.  Numbering
the gaps might help to concentrate the text on linking together (or separating)
problems into well-defined sets.

s5.1, para 1: s/enable/make it possible for/; s/single/a single/

s5.1, first bullet: s/this may also require to transfer/this may also require
the transfer of/

s5.1, para after 2nd bullet: s/therefore providing/thereby providing/

s5.1, 2nd para after 2nd bullet:
OLD:
    where the mobility
    client natively knows each anchor associated to each mobility
    sessions.
NEW:
    where the mobility
    client natively knows the anchor associated with each of its mobility
    sessions.

s5.1, 3rd para after 2nd bullet: s/to allow dynamically discovering the
presence of nodes/to allow
    the dynamic discovery of the presence of nodes/;
    s/to allow selecting a node/to allow the selection of a node/
  and...
OLD:
    There are though some mechanisms
    that could help discovering anchors, such as the Dynamic Home Agent
    Address Discovery (DHAAD)
NEW:
    However, there are some mechanisms
    that could help to discover anchors, such as the Dynamic Home Agent
    Address Discovery (DHAAD)
Additionally: Does DHAAD deserve a reference?

s5.1, last para:  I have suggested some changes to make this clearer (I hope):
OLD:
    Also note that REQ1 is such that the data plane traffic can avoid
    suboptimal route.  Distributed processing of the traffic is then
    needed only in the data plane.  The needed capability in distributed
    processing therefore should not contradict with centralized control
    plane.  Other control plane solutions such as charging, lawful
    interception, etc. should not be limited.  Yet combining the control
    plane and data plane forwarding management (FM) function may limit
    the choice to distributing both data plane and control plane
    together.  In order to enable distributing only the data plane
    without distributing the control plane, a gap is to split the
    forwarding management function into the control plane (FM-CP) and
    data plane (FM-DP).
NEW:
    Also note that REQ1 is intended to prevent the data plane traffic taking a
    suboptimal route.  Distributed processing of the traffic is then, hopefully,
    needed only in the data plane.  Provision of this capability for distributed
    processing should not conflict with the use of a centralized control
    plane.  Other control plane solutions such as charging, lawful
    interception, etc. should not be constrained by the DMM solution.  On the
    other hand combining the control plane and data plane forwarding management
    (FM) function may limit the choice of solutions to those that distribute
    both data plane and control plane together.  In order to enable
    distribution of only the data plane without distributing the control
    plane,it would be necessary to split the forwarding management function
    into control plane (FM-CP) and data plane (FM-DP) components; there is
    currently a gap here.

s5.2, para 1: s/flexibility on determining/flexibility in determining/;
s/whether or not use/whether or not to use/

s5.2, para 1:

  It only enables the two following functions:

I am not sure what 'it' refers to here.  Is this the functionality that is
needed to implement REQ1? Or what?

s5.2, 1st bullet: s/which uses/which use/

s5,2, 1st para after bullets: s/to indicate the IP stack/to indicate to the IP
stack/

s5,2, 1st para after bullets:

mobility support is required or not in.

Either the 'in' is redundant or there is a phrase missing at the end.

s5.2, next to last para:
s/there exist these individual efforts that/these individual efforts and they/

s5.4, para 2: s/nothing prevent/nothing prevents/; s/functions with in IP
mobility/functions within IP mobility/

s5.4, last para: s/going into the direction/going in the direction/

s5.5: s/the needed mobility management/the necessary mobility management/

s5.6, bullet 6: s/of forwarding path/of the forwarding path/

s5.6, para after bullets: s/the above list of operation/how, or whether, they
support the above list of operation/

s5.7: Everything after the first sentence is either 'motherhood and apple pie'
or statements
  of things that allegedly work.  No gaps are identified - so everything except
  the first sentence
could probably be replaced with:
    Any solutions that are intended to fill in gaps identified in this document
    need to meet this requirement.  At present, it does not appear that using
    existing solutions to support DMM has introduced any new security issues.

s5.8, para 1: s/to enable multicast solutions to be developed/to allow the
development of multicast solutions/

s5.8, para 2: s/insta ces/instances/

s5.9, bullet 1: s/to very narrow use case./to a very narrow use case./

s5.9, bullet 2: s/requires to expose/requires the exposure of/

s5.9, bullet 3: s/allows to dynamically discover/allows the dynamic discovery
of/

s5.9, bullet 5: s/may allow to deploy/may allow the deployment of/

s6: s/encounter same security/encounter the same security/