Requirements for Advanced Multipath in MPLS Networks
draft-ietf-rtgwg-cl-requirement-16

[Ballot comment]
As I mentioned to Stewart privately, I clicked too fast on "no objection" 2 days ago.

I found this draft not easy to read. I had to re-read a few paragraphs/sentences multiple times

-

  Other
  services will continue to require only that reordering not occur
  within a microflow as is current practice.


The definition speaks of flow, not microflow

-

OLD:
  The intent is to first provide a set
  of functional requirements that are as independent as possible of
  protocol specifications in Section 3. 

NEW:

  The intent is to first provide a set
  of functional requirements, in Section 3, that are as independent as possible of
  protocol specifications

-
Section 1.1
  The implementation SHOULD in most or all
  cases allow any new functionality to be individually enabled or
  disabled through configuration.

Isn't a requirement? Shouldn't it have his own REQ number?

-
  A service provider or other
  deployment MAY enable or disable any feature in their network,
  subject to implementation limitations on sets of features which can
  be disabled.

Not sure what this sentence means. What is the requirement, if any?

- What is the meaning of MAY in requirements, like in FR 22

-
Composite Link
      The term Composite Link had been a registered trademark of Avici
      Systems, but was abandoned in 2007.  The term composite link is
      now defined by the ITU-T in [ITU-T.G.800].  The ITU-T definition
      includes multipath as defined here, plus inverse multiplexing
      which is explicitly excluded from the definition of multipath.

What don't you define what it is (I can only guess), then add a note about the ITU-T relationship



-
  Client Layer
      A client layer is the one immediately above a server layer.

  Server Layer
      A server layer is the latey immediately below a client layer.

A is left to B, and B is right to A ... still doesn't tell me what A and B are.

-
Inverse Multiplexing
      Inverse multiplexing either transmits whole packets and
      resequences the packets at the receiving end or subdivides
      packets and reassembles the packets at the receiving end.
      Inverse multiplexing requires that all packets be handled by a
      common egress packet processing element and is therefore not
      useful for very high bandwidth applications.

I still don't know what Inverse Multiplexing is

-
Flow identification.
How does it relate to the flow definition in RFC 7011?

-
  A Component Link may be a point-to-point physical link (where a
  "physical link" includes one or more link layer plus a physical
  layer) or a logical link that preserves ordering in the steady state.
  A component link may have transient out of order events, but such

You should really be consistent regarding capitalized terms from the terminology section, throughout the document.
Here, Component Link versus component link

-

  Use of the term "advanced multipath" outside this document, if
  referring to the term as defined here, should indicate Advanced
  Multipath as defined by this document, citing the current document
  name.  If using another definition of "advanced multipath", documents
  may optionally clarify that they are not using the term "advanced
  multipath" as defined by this document if clarification is deemed
  helpful.

Isn't it obvious?

-
FR#26 If the total demand offered by traffic flows exceeds the
      capacity of the AMG,

offered or required?

-
  A delay discontinuity is an isolated event which may greatly exceed
  the normal delay variation (jitter).  A delay discontinuity has the
  following effect.  When a flow is moved from a current link to a
  target link with lower latency, reordering can occur.  When a flow is
  moved from a current link to a target link with a higher latency, a
  time gap can occur.  Some flows (e.g., timing distribution, PW
  circuit emulation) are quite sensitive to these effects.  A delay
  discontinuity can also cause a jitter buffer underrun or overrun
  affecting user experience in real time voice services (causing an
  audible click).  These sensitivities may be specified in a
  Performance Objective.

There is some information on this one in RFC 5481

[Ballot comment]
Updated after discussion with the Editor.

---

I am not going to insist that section 3.2 is removed, but this section seems to me to be out of place in this document. I would be pleased to see it go, but am not exercised by its presence. The reasoning for removing it is that there is nothing here that describes the behaviour of AMGs per se. Instead the text is about how information about links is reported from one layer to another.

---

It would be nice if the concise "Abstract Multipath" definition in the Abstract were copied to the Intro.

---

Andy Malis may want to change his coordinates.

[Ballot discuss]
I wanted to ballot Yes on this document, and may be able to move there
are we have Disucssed these points:

---

Why is Seciton 3.2 particular to this document? Any link may be provided
by a lower layer network. And in that case the latency of the client
link is a function of the latency of the server trail.

I can understand that this is important to ensure that the component
links in the AMG have sufficiently similar latency, but I don't see that
the requirements here are specifically stated in a way that is relevant
to AMGs. That needs to be clarified or the section removed from this
document.

In fact, I think that the requirements in Section 3.3 (for example,
FR#12) cover this issue.

---

GMPLS includes the concept of the protection level offered by a link.
This is easy to set up when the component link is built from a trail
(or a set of trails in a protection arrangement) in a server layer.

How does protection work within an AMG? Is this something to add to
section 3.3 or does it warrant more discussion?

[Ballot comment]
Andy Malis may want to change his coordinates.

---
                       
The Abstract contains a 3 line description of "Advanced multipath".
Something similar (although maybe longer) could usefully be added to
the Introduction since the reader may need this background. (This,
notwithstanding the helpful and more lengthy discussion in Seciton 2.)

---

I'm a little surprised that there are no security requirements. For
example, is there not a case for link-level security on the component
links (equivalent to L2 security) that implies a desire for security
on the server trails?

[Ballot comment]
Non-blocking comments: please consider them, and chat with me if you like... but no response is required.

-- Section 3.5 --

  FR#22 Load balancing MAY be used during sustained low traffic periods
      to reduce the number of active component links for the purpose of
      power reduction.

I'm very suspicious of "MAY" in requirements -- what does it mean here?  The fact that load balancing is entirely optional doesn't seem like a "requirement".

The same is true of GR#4 in Section 4.

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-rtgwg-cl-requirement-13, which is currently in Last Call, and has the following comments:

We understand that this document doesn't require any IANA actions. IANA requests that the IANA Considerations section of the document remain in place upon publication.

If this assessment is not accurate, please respond as soon as possible.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Requirements for Advanced Multipath in MPLS Networks) to Informational RFC


The IESG has received a request from the Routing Area Working Group WG
(rtgwg) to consider the following document:
- 'Requirements for Advanced Multipath in MPLS Networks'
  as Informational 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 2013-12-09. 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


  This document provides a set of requirements for Advanced Multipath
  in MPLS Networks.

  Advanced Multipath is a formalization of multipath techniques
  currently in use in IP and MPLS networks and a set of extensions to
  existing multipath techniques.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-rtgwg-cl-requirement/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-rtgwg-cl-requirement/ballot/


No IPR declarations have been submitted directly on this I-D.

I draw readers attention to the following note in the Shepherds report:

"After the last WGLC completed, there was concern about the terminology of
composite link not quite matching that used in the ITU.  The draft has been
updated to use the term "Advanced Multipath" instead.  Some additional
simplifications were also made by the authors' agreement."

In view of the changes to the text starting a second IETF Last Call.

(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?

Informational.  Draft discusses requirements and no implementable aspects.
Yes, RFC type 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

  There is often a need to provide large aggregates of bandwidth that
  are best provided using parallel links between routers or MPLS LSP.
  In core networks there is often no alternative since the aggregate
  capacities of core networks today far exceed the capacity of a single
  physical link or single packet processing element.

  The presence of parallel links, with each link potentially comprised
  of multiple layers has resulted in additional requirements.  Certain
  services may benefit from being restricted to a subset of the
  component links or a specific component link, where component link
  characteristics, such as latency, differ.  Certain services require
  that an LSP be treated as atomic and avoid reordering.  Other
  services will continue to require only that reordering not occur
  within a microflow as is current practice.

Working Group Summary

Interest in the draft was mild - focus mostly from a small set of participants
and the co-authors.  There were no contentious points.  There was discussion
about the value of DR#6 where the overhead of just signaling the composite link
members may be better than dealing with crankback or poor summarization.
The work can support both approaches.

After the last WGLC completed, there was concern about the terminology of
composite link not quite matching that used in the ITU.  The draft has been
updated to use the term "Advanced Multipath" instead.  Some additional simplifications were also made by the authors' agreement.

Document Quality

The document is well written and has been updated with focus several times.
It has benefited from having Curtis Villamizar being a focused and motivated
editor for this and the related drafts.

There are no existing implementations, as makes sense for a requirements draft.


Personnel

Document Shepherd: Alia Atlas
Responsible AD:  Stewart Bryant

(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 reviewed this draft at WGLC as well as several times previously.  I also
reviewed it in the context of the associated drafts.  I've reviewed the differences
between the -11 and -13 versions.

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

While I would have liked to have seen more interest from a larger portion
of the WG, the Composite Link work has gotten good review over the past
several years.  It is clearly a more niche topic.

(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 particular review is specifically needed. 

(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.

My only concern is that Composite-Links are a bit of a niche area.  Nonetheless,
the WG has not had any concerns about the work moving forward.

(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, each author has confirmed the lack of any associated IPR; thus all
appropriate IPR disclosures (none) have been filed.

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

No

(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? 

It represents the strong concurrence of a few individuals with others occasionally
chiming in and no disagreement.

(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 http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

None found.

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

None needed

(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.

None

(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.

Will not affect other existing RFCs

(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).

No IANA work needed.

(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.

None

(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.

None

(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?

Informational.  Draft discusses requirements and no implementable aspects.
Yes, RFC type 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

  There is often a need to provide large aggregates of bandwidth that
  are best provided using parallel links between routers or MPLS LSP.
  In core networks there is often no alternative since the aggregate
  capacities of core networks today far exceed the capacity of a single
  physical link or single packet processing element.

  The presence of parallel links, with each link potentially comprised
  of multiple layers has resulted in additional requirements.  Certain
  services may benefit from being restricted to a subset of the
  component links or a specific component link, where component link
  characteristics, such as latency, differ.  Certain services require
  that an LSP be treated as atomic and avoid reordering.  Other
  services will continue to require only that reordering not occur
  within a microflow as is current practice.

Working Group Summary

Interest in the draft was mild - focus mostly from a small set of participants
and the co-authors.  There were no contentious points.  There was discussion
about the value of DR#6 where the overhead of just signaling the composite link
members may be better than dealing with crankback or poor summarization.
The work can support both approaches.

After the last WGLC completed, there was concern about the terminology of
composite link not quite matching that used in the ITU.  The draft has been
updated to use the term "Advanced Multipath" instead.  Some additional simplifications were also made by the authors' agreement.

Document Quality

The document is well written and has been updated with focus several times.
It has benefited from having Curtis Villamizar being a focused and motivated
editor for this and the related drafts.

There are no existing implementations, as makes sense for a requirements draft.


Personnel

Document Shepherd: Alia Atlas
Responsible AD:  Stewart Bryant

(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 reviewed this draft at WGLC as well as several times previously.  I also
reviewed it in the context of the associated drafts.  I've reviewed the differences
between the -11 and -13 versions.

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

While I would have liked to have seen more interest from a larger portion
of the WG, the Composite Link work has gotten good review over the past
several years.  It is clearly a more niche topic.

(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 particular review is specifically needed. 

(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.

My only concern is that Composite-Links are a bit of a niche area.  Nonetheless,
the WG has not had any concerns about the work moving forward.

(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, each author has confirmed the lack of any associated IPR; thus all
appropriate IPR disclosures (none) have been filed.

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

No

(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? 

It represents the strong concurrence of a few individuals with others occasionally
chiming in and no disagreement.

(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 http://www.ietf.org/tools/idnits/ and the Internet-Drafts
Checklist). Boilerplate checks are not enough; this check needs to be
thorough.

None found.

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

None needed

(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.

None

(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.

Will not affect other existing RFCs

(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).

No IANA work needed.

(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.

None

(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.

None

IESG/Authors/WG Chairs:

IANA has reviewed draft-ietf-rtgwg-cl-requirement-10, which is currently in Last Call, and has the following comments:

We understand that, upon approval of this document, there are no IANA
Actions that need completion.

If this assessment is not accurate, please respond as soon as possible.

The following Last Call announcement was sent out:

From: The IESG
To: IETF-Announce
CC:
Reply-To: ietf@ietf.org
Sender:
Subject: Last Call:  (Requirements for Composite Links in MPLS Networks) to Informational RFC


The IESG has received a request from the Routing Area Working Group WG
(rtgwg) to consider the following document:
- 'Requirements for Composite Links in MPLS Networks'
  as Informational 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 2013-06-19. 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


  There is often a need to provide large aggregates of bandwidth that
  are best provided using parallel links between routers or MPLS LSR.
  In core networks there is often no alternative since the aggregate
  capacities of core networks today far exceed the capacity of a single
  physical link or single packet processing element.

  The presence of parallel links, with each link potentially comprised
  of multiple layers has resulted in additional requirements.  Certain
  services may benefit from being restricted to a subset of the
  component links or a specific component link, where component link
  characteristics, such as latency, differ.  Certain services require
  that an LSP be treated as atomic and avoid reordering.  Other
  services will continue to require only that reordering not occur
  within a microflow as is current practice.




The file can be obtained via
http://datatracker.ietf.org/doc/draft-ietf-rtgwg-cl-requirement/

IESG discussion can be tracked via
http://datatracker.ietf.org/doc/draft-ietf-rtgwg-cl-requirement/ballot/


No IPR declarations have been submitted directly on this I-D.