Re: [PCN] FW: New Version Notification - draft-ietf-tsvwg-rsvp-pcn-03.txt

<karagian@cs.utwente.nl> Sat, 09 March 2013 12:04 UTC

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Subject: Re: [PCN] FW: New Version Notification - draft-ietf-tsvwg-rsvp-pcn-03.txt
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Hi Bob,



Thanks for your comments!
Please see in line!



> -----Original Message-----
> From: Bob Briscoe [mailto:bob.briscoe@bt.com]
> Sent: donderdag 15 november 2012 22:35
> To: Karagiannis, G. (EWI); Anurag Bhargava (anuragb)
> Cc: pcn@ietf.org<mailto:pcn@ietf.org>; tsvwg@ietf.org<mailto:tsvwg@ietf.org>; rsvp-dir@ietfa.amsl.com<mailto:rsvp-dir@ietfa.amsl.com>
> Subject: Re: [PCN] FW: New Version Notification - draft-ietf-tsvwg-rsvp-pcn-
> 03.txt
>
> Georgios & Anurag,
>
> Thank you for this draft. Below is my review, as:
> - a member of the RSVP directorate
> - one of the PCN design team
> - a co-author of draft-lefaucheur-rsvp-ecn, on which this draft is based.
>
> I have already sent my main technical concerns in two separate emails,
> summarised below (but I suggest we use the separate threads to discuss):
>
> 1. It would be easy to allow for an off-path policy-decision point (PDP), as per
> RFC2753 (policy-based admission control (PBAC) framework)

Georgios: I replied to your above proposal in a previous email!
>
> 2. PCN already reduces reservation state and processing to nothing on
> interior nodes. Adding aggregate reservations to PCN adds 3 disadvantages
> and no advantages:
> - it requires more processing and state in interior nodes and boundary-
> nodes
> - it unnecessarily pins routes to interior nodes and
> - it adds unnecessary latency.



Georgios: I answered to the thread mentioned above in a previous email sent today! However, I would like to again emphasize that I strongly agree with the analysis done by Francois (together with my additional email) in the following email on the two options of accomplishing RSVP over PCN signaling support:
http://www.ietf.org/mail-archive/web/tsvwg/current/msg11601.html
http://www.ietf.org/mail-archive/web/tsvwg/current/msg11602.html

In addition to that, we agree with the proposal of Francois of choosing option (A)  since the RFC4860 operations has been thought through and there has been some implementation of RSVP Aggregation, so we have some confidence that the solution can deal with the more challenging situations (rerouting in core, failure of an ingress edge, failure of an egress edge, rerouting towards a different edge,…).

Therefore, we have used the argumentation provided by Francois in Section 1.2 of (new draft version) draft-ietf-tsvwg-rsvp-pcn-04 to justify why RFC4860 should be used to accomplish the RSVP over PCN signaling support.

>
> This email reviews comprehensibility and raises a large number of lesser
> technical concerns (26 to be precise), as well as editorial nits (many of which
> may be irrelevant if I'm right about the major technical concerns).
>
> ==General style==
> I didn't find the style useful at all. Sections 1, 2 & 3 defer everything
> meaningful into pointers to other RFCs. This makes it incomprehensible,
> even if you know all the references intimately.
> Lixia's suggestion that you refer to the specific sections of other RFCs won't
> be enough.
>
> An RFC should be understandable without re-reading its references (readers
> should have read them, but they shouldn't be expected to remember every
> detail).



Georgios: We have severely restructured the (new draft) draft-ietf-tsvwg-rsvp-pcn-04. We believe that the above comment has been worked out!



>
> I have to say we are moving very slowly, and backwards. When Francois Le
> Faucheur first wrote the ancestor to this draft (7 years ago!), I could
> understand it immediately, and in half the pages it covered nearly everything
> in this draft and covered the gaps I have listed below. [In the interests of full
> disclosure: I became a co-author of draft-lefaucheur-tsvwg-rsvp-ecn-00,
> nonetheless Francois's pre-00 draft was more comprehensible and complete
> than this one, even before the co-authors did the first reviews.]

Georgios: I do not agree! Note that draft-lefaucheur-tsvwg-rsvp-ecn-00 does not follow the PCN signaling requirements defined in [RFC6663] and it does not how it can support the PCN edge behaviors as specified in [RFC6661] and [RFC6662]. While draft-ietf-tsvwg-rsvp-pcn-04 certainly does this.



>
> This draft says very little itself, but ends up much longer. For example Section
> 3 tediously repeats content-free text like:
> "<Title>
> In this document it is considered that for <Title> the same methods can be
> used as the ones described in <reference>".
>
> Not only section 3; sections 1 & 2 also rely wholly on references, making
> them just as incomprehensible. I also agree with the other reviewers'
> suggestions to focus the introduction initially on what this draft adds, and
> move the background material after that.
>
> In summary: avoid phrases like "the same methods as" or "standard RSVP
> aggregation [...] procedures are used". Instead just say directly how it works.



Georgios: We have severely restructured and re-edited the (new draft) draft-ietf-tsvwg-rsvp-pcn-04. We believe that the above comment has been worked out!



>
>
> ==Normative & Technical Points==
>
> ==Gaps==
>
> * How an aggregate reservation is created vs. how one is used if it is already
> present



Georgios: Done: Added the following text in Section 2.1 to address this issue:
“The procedures for aggregation of E2E reservations over generic aggregate RSVP reservations are the same as the procedures specified in Section 4 of [RFC4860].



>
> * How next hop addresses are discovered (a PCN domain is only one RSVP
> hop unlike with RSVP aggregation, so although the process is similar, this
> needs to be described explicitly)



Georgios: This is explained in the (new draft) draft-ietf-tsvwg-rsvp-pcn-04. In particular, the PCN-domain is considered as being only one RSVP hop (for Generic aggregated RSVP or e2e RSVP). This means that the next RSVP hop for the Aggregator in the downstream direction is the Deaggregator and the  next RSVP hop for the Deaggregator in the upstream direction
is the Aggregator. Furthermore, it is considered that for the determination of the Deaggregator, the same methods can be used as the ones described in Section 4 of [RFC4860].

>
> * How PCN interior nodes ignore RSVP messages:
> - by configuration?
> - or by the PCN-ingress switching aggregate PATH messages to IP protocol
> number RSVP-E2E-IGNORE (which isn't strictly the right name but would have
> the right effect)?
>



Georgios: We mentioned in the new version of the draft that the PCN interior nodes ignore aggregated and e2e RSVP messages by configuration.



> * Error conditions, for instance when messages don't contain the expected
> objects, e.g. [draft-lefaucheur-tsvwg-rsvp-ecn-01, page 6 bullet 1].



Georgios: Please note that the PCN object is carried using the Aggregated RESV message, and not the e2e RESV message, meaning that the above issue is not relevant.

>
> * How per-node state is maintained and the interaction with RSVP soft state
> refresh messages is not discussed. PCN-related state is unlike other RSVP
> state, in that it continually varies (it is controlled by a varying signal).
> Therefore it needs to be clear that the fields of the PCN object reflect the
> current value when sent, not their original value, which is what an RSVP
> implementer would normally expect.



Georgios: Please note that the PCN object is carried using the Aggregated RESV message, and not the e2e RESV message, meaning that the above issue is not relevant.

>
> ==Specific sections==
>
> 1. Introduction
>
> " This document, and according to [RFC4860] MAY also be used end-to-end
> directly by end-systems attached to a Diffserv network.
> "
> No. See RFC5559 for PCN applicability - there is insufficient aggregation for
> PCN to work effectively e2e. The PCN applicability statement in RFC5559
> should be stated here instead: PCN is only applicable to links with
> aggregation levels where the bit-rate of the largest flow is tens of times
> smaller than the smallest available link rate in the PCN region.



Georgios: We removed the paragraph pointed out above!



>
> OLD:
> In this document it is considered that the PCN-nodes MUST be able to
> support the functionality specified in [RFC5670], [RFC5559],
> [RFC6660], [RFC6661], [RFC6662].
> NEW:
> To comply with this specification, PCN-nodes MUST be able to
> support the functionality specified in [RFC5670], [RFC5559]
> [RFC6660], and either [RFC6661] or [RFC6662].



Georgios: Done!



>
> Section 2.1 first para:
> " In addition, in this document it is considered that the PCN-boundary
> nodes are able to distinguish and process (1) RSVP SESSIONS for
> generic aggregated sessions and their messages according to
> [RFC4860], (2) e2e RSVP sessions and messages according to [RFC2205].
> "
> Say how (by the addresses that the RSVP messages are addressed to).



Georgios: Done! We added text to address this point: “In addition, to comply with this specification it is considered that the PCN-boundary nodes are able to distinguish by using the addresses that the RSVP messages are addressed to,”

>
> " Furthermore, it is considered that the PCN-interior-nodes are not
> able to distinguish neither RSVP generic aggregated sessions and
> their associated messages [RFC4860], nor e2e RSVP sessions and their
> associated messages [RFC2205].
> "
> Say how (see two possibilities in 'Gaps' above). This is also not
> explained in Sections 2.1.7., 3.2 & 3.7, which are all meant to be about this.

Georgios: Done! We added the required information in all the mentioned places. In particular we mentioned that:

“Furthermore, it is considered that by configuration the PCN-interior-nodes are not able to distinguish neither RSVP generic
aggregated sessions and their associated messages [RFC4860], nor e2e RSVP sessions and their associated messages [RFC2205].”

>
> Section 2.1 bottom of p11:
> "The RSVP SESSION object for generic
> aggregate reservations is based on the RSVP SESSION object specified
> in [RFC4860] augmented with the following information:
>
> o) the IPv4 DestAddress, IPv6 DestAddress SHOULD be set to the IPv4
> or IPv6 destination addresses, respectively, of the Deaggregator
> (PCN-egress-node)
> "
> Say how - see 'Gaps' above - the whole process of RFC4860 (e2e PATH,
> e2e PathErr, aggregate PATH) finds the right address, but this needs
> to be described because in PCN the RSVP hop is across multiple IP
> nodes (the whole PCN-domain), unlike with RSVP aggregation.



Georgios: Done! We have addressed this point, see also gaps above. In the new version of the draft we replaced the above bullet with:

    o) the IPv4 DestAddress, IPv6 DestAddress MUST be set to the IPv4
       or IPv6 destination addresses, respectively, of the Deaggregator
      (PCN-egress-node), see [RFC4860]. Note that the PCN-domain is
       considered as being only one RSVP hop (for Generic aggregated
       RSVP or e2e RSVP). This means that the next RSVP hop for the
       Aggregator in the downstream direction is the Deaggregator and
       the  next RSVP hop for the Deaggregator in the upstream direction
       is the Aggregator. Furthermore, it is considered that for the
       determination of the Deaggregator, the same methods can be used
       as the ones described in Section 4 of [RFC4860].

>
> Section 2.1.2.
> " The PCN-traffic (e.g., e2e microflows) belonging to an ingress-
> egress-aggregate can be classified only at the PCN-boundary-nodes
> using the combination of (1) PCN-BA (i.e., combination of the DSCP
> and ECN fields), (2) IP addresses of the specific pair of PCN-
> boundary-nodes used by a ingress-egress-aggregate.
> [...]
> Moreover, the PCN-traffic (e.g., e2e microflows)
> belonging to a RSVP generic aggregated reservation can be classified
> only at the PCN-boundary-nodes (i.e., Aggregator and Deaggregator) by
> using the RSVP SESSION object for RSVP generic aggregated
> reservations, see [RFC4860].
> "
> Are you assuming a tunnel? You haven't said so? Otherwise the traffic
> doesn't contain the PCN-boundary-node addresses.



Georgios: Done! We added information saying that it is
   considered that tunnels need to be used between Aggregators and
   Deaggregators, using the same procedures as specified in Section 4 of
   [RFC4860].



>
> Section 2.1.8. Inter-domain Routes
>
> PCN charter scope precludes inter-domain considerations. I personally
> would happy to have discussion of inter-domain matters in here, but
> it will not be complete, because we would need to discuss security &
> integrity of PCN objects, but the PCN charter precluded that.



Georgios: Done! We changed this section as below:

The PCN-charter scope precludes inter-domain considerations. However, for solving inter-domain routes changes associated with the operation of the RSVP messages, the same methods SHOULD be used as the ones described in [RFC4860] and in Section 1.4.7 of [RFC3175].



>
> Section 2.1.10. Multi-level Aggregation
> " PCN does not consider multi-level aggregations within the PCN domain.
> "
> You have referenced generic aggregate reservations throughout
> [RFC4680], rather than just aggregate reservations [RFC3175]. I
> understand the difference is that RFC4860 supports e.g. multiple
> levels of precedence. So why say we don't consider multi-level aggregation?



Georgios: Done! We replaced the old text with the following one:
PCN does not consider multi-level aggregations within the PCN domain. Therefore, the PCN-interior-nodes are not supporting multi-level aggregation procedures. However, the Aggregator and Deaggregator SHOULD support the multi-level aggregation procedures specified in [RFC4860] and in Section 1.4.9 of [RFC3175].



>
> Section 3.1
> " o) The e2e RSVP reservation session associated with an e2e Path
> message that arrives at the external interface of the PCN-
> ingress-node is mapped/matched onto an existing RSVP generic
> aggregation reservation state.
> "
> You haven't said how the existing aggregate is created in the first
> place (see 'Gaps' above).



Georgios: Done! See the gaps description above!



>
> Section 3.1 (twice)
> " A new error code
> "PCN-domain rejects e2e reservation" MUST be augmented to the
> RSVP error codes to inform the sender that a PCN domains rejects
> the e2e reservation request.
> "
> Disagree. The regular error code "01: Admission Control failure"
> should be used, so that end-system implementations understand that
> the call has been blocked.
> It should also use the regular "Sub-code = 2: Requested bandwidth
> unavailable".
>
> If the PCN-ingress uses a different code, it will imply to other RSVP
> nodes including end-systems that admission control did not fail. If
> it uses the 01 error code but a different sub-code it will imply that
> AC failed, but not because of insufficient bandwidth.
>
> PCN is one (of many) mechanisms to determine whether a reservation
> should be blocked. For other nodes, it is not relevant to describe
> the mechanism (PCN) that was used to determine that there was
> insufficient bandwidth.



Georgios: Done! We changed the above mentioned text with:
The admission or rejection procedure of a PCN-flow into the PCN-domain is defined in detail in: [RFC6661] and [RFC6662].
If the Aggregator is not able to admit the e2e microflow it SHOULD then generate an e2e PathErr message using standard e2e RSVP procedures [RFC4495]. This e2e PathErr message is sent to the originating sender of the e2e Path message. The e2e RSVP error code "01: Admission Control failure" and the "Sub-code = 2: Requested bandwidth unavailable " specified in Appendix B of [RFC2205] SHOULD be used for this purpose.

>
> Section 3.1
> " o) If for the same ingress-egress-aggregated and the same RSVP
> generic aggregated reservation then (1) the PCN-admission-
> state and/or (2) the state for the RSVP generic aggregated
> reservation are/is "block", the flow SHOULD NOT be
> admitted
> [...]
> The way of how the PCN-admission-state is maintained is specified in
> [RFC6661] and [RFC6662]. The way of how the RSVP generic aggregated
> reservation state is maintained is specified in [RFC4860].
> "
> As discussed in my email arguing against aggregate reservations, the
> e2e RESV message can carry an up-to-date PCN object for the
> PCN-ingress to decide whether to admit the flow signalled by the same
> message, given the PCN-ingress already handles e2e RESV messages.
> There is no need to rely on admission state determined earlier, given
> the PCN-egress already sends an e2e RESV message to the PCN-ingress
> at admission time.



Georgios: Note that using e2eRESV to carry the PCN object has severe drawbacks, see above and the previous emails sent by me today. Moreover, the description that you Bob provide above, on PCN admission control is not in line with what is defined in the current PCN edge behaviour drafts.



>
> Section 3.2 and 3.7 (and 2.1.7).
> Neither section says how interior nodes are arranged to ignore RSVP
> messages (see 'Gaps' earlier which suggests two possible approaches).



Georgios: Done, see Gaps description above!



>
> Section 3.8 (last sentence)
> " The address of the PCN-ingress-
> node is the one specified in the same ingress-egress-aggregate."
> I cannot work out how



Georgios: Done! We have added the following text:

It is considered that the ingress-egress-aggregate state stores both IP addresses of the PCN-ingress-node, i.e., Aggregator, and of the IP-egress-node, i.e., Deaggregator.



>
> Section 3.11
> Separation of the policy enforcement role of the PCN-ingress from a
> policy decision role (that may be off-path) will need to be added to
> the first bullet of this section (see other email).



Georgios: We disagree with this comment! We think that the description of such a policy-based admission control (PBAC) architecture is not in the scope of this draft. See also my previous email sent today!
We however, tried to work out this comment by including the following text:

    “o)  If the Decision Point is not collocated with the PCN-ingress-
        node, then other procedures need to be specified of handling the
        Aggregated Resv Message by the Aggregating router, i.e., PCN-
        ingress-node. These procedures are out of the scope of this
        document.

    o)  If the Decision point is collocated with the PCN-ingress-node,
        then the PCN-ingress-node (i.e. Aggregator) ..”



>
> Section 3.11
> " However, based on a local policy, the Aggregator could use
> other procedures of terminating microflows.
> "
> Please delete. Policy determines /which/ flows are terminated, not
> /how/ the termination procedure works.



Georgios: Done! We tried to work out this comment by modifying the text as follows:
“However, based on a local policy, the Aggregator could use other ways of selecting which microflows should be terminated.”



>
> Section 3.12
> I don't understand the purpose of this section - section 3.11 seems
> to have already said everything that section 3.12 says.



Georgios: We re-edit the section to satisfy the above comment!



>
> Section 3.13
> Say why an aggregate reservation would need to be removed:
> - no e2e reservations left in the aggregate?
> - such severe pre-congestion that every flow in the aggregated has to
> be terminated (!!!???)
>



Georgios: Done! We reedited the section to comply with this comment!

> Section 4. Protocol Elements
> " The protocol elements in this document are using the protocol
> Elements defined in [RFC4860], augmented with the following rules:
> "
> This doc uses a number of protocol elements from the base RSVP spec,
> not just the extras defined in RFC4860.
>
> BTW, protocol elements are generally called classes in RSVP documents
> (and instances of them are called objects). Also the grammar and
> capitalisation in this sentence is pretty poor.



Georgios: Please note that we used the same terms (related to protocol elements) as the ones used in RFC4860 and RFC3175.

>
> Section 4. Protocol Elements
> The first two bullets are inappropriate here and more appropriate to section
> 3.



Georgios: These two bullets are used i this section to increase the clarity of the specification!



>
> Section 4.1 PCN Object
>
> I don't see why the PCN object needs to contain the IP addresses of
> the PCN-ingress and PCN-egress. These will be in the SESSION object
> earlier in the list of RSVP objects, and RFC2205 says that the
> SESSION object defines the session for the other objects that follow.
> This also means we don't need different PCN objects for IPv4 & IPv6.



Georgios: We provided text in the new draft draft-ietf-tsvwg-rsvp-pcn-04, that emphasizes that according to [RFC6663] the report should carry the identifier of the PCN-ingress-node and the identifier of the PCN-egress-node (typically their IP addresses).
This means that the different types for PCN objects for IPv4 & IPv6 are needed.



>
> Section 4.1 PCN Object
>
> s/rate/fraction/
> I don't think you mean rate, which implies with respect to time. I
> think you mean the fraction of bytes in packets with each marking
> relative to the total bytes in PCN marked packets.



Georgios: It is rate (respect to time), please see [RFC6663] and [RFC6661] and [RFC6662].



>
> Section 4.1 PCN Object
>
> I suggest that the PCN object always reports the fractions of all
> three non-zero values of the PCN (aka ECN) field, even for single
> marking (SM) mode that doesn't use one of the codepoints. Then
> PCN-egress implementations and the PCN object on the wire can be the
> same for both SM & CL modes (I think), and only the ingress has to be

> different.



Georgios: Sorry, but the above description is not in line with RFC6663] and [RFC6661] and [RFC6662].

>
> Section 4.1 PCN Object (and IANA Considerations)
>
> IANA need to be told the high order 2 bits of the Class-Num, to
> exploit the Unknown Class rules of [RFC2205, section 3.10]. I suggest
> the Class-Num is 10bbbbbb, so that any node outside a PCN domain that
> receives a PCN object and doesn't understand it will strip it off and
> forward the remainder of the RSVP message. Ideally we would want the
> RSVP message (with or without the PCN object) to be forwarded and an
> error message raised, but that option is not available; RSVP only
> allows an error message to be raised when it discards a whole message.



Georgios: Please note that the PCN object is carried by the Aggregated RESV message. This message does not go out the PCN domain. Thus the above described issue is not relevant for this draft.



>
> Section 4.1 PCN Object
>
> The section defines a PCN CL Flow IDs object. It's not clear whether
> it is meant to be a different object from the PCN object, or an
> extension to it. I think it would be clearer to make it a separate
> RSVP object, although in theory a PCN-ingress could work out that a
> PCN CL Flow IDs object is included, by a calculation from the object
> length (because the base PCN object is always a fixed length).
>
> I don't see the point of the LENGTH field (for the number of flow ID
> objects), given RSVP gives the length of an object in octets, from
> which the number of flow ID objects can be derived (divide by 16 for
> IPv4 or divide by 40 for IPv6). Also RSVP objects have to align on 4
> octet boundaries.



Georgios: Please note that the PCN CL Flow IDs object is considered to be a different PCN object, since its frequency and functionality is very much different than the frequency and functionality of the other PCN objects.
Regarding the length, I do not understand the comment, since such length field is necessary, due to e.g., variable length of the object.



>
>
>
> ==Editorial Nits==
>
> Globally:
> s/In this document it is considered that.../
> /To comply with this specification.../



Georgios: Done!



>
> Abstract:
> s/specifies the extensions to/
> /specifies extensions to/



Georgios: Done!



>
> 1. Intro
> s/collocated/
> /colocated/
> s/extensions to the Generic Aggregated RSVP [RFC4860] for the support of/
> /extensions to Generic Aggregated RSVP [RFC4860] for support of/



Georgios: Done!



>
> OLD
> Furthermore, this document and according to [RFC4860], in absence of
> e2e RSVP flows, a variety of policies (not defined in this document)
> can be used at the Aggregator to set the DSCP of packets passing into
> the aggregation region and how they are mapped onto generic aggregate
> reservations. These policies are not described in this document but
> are a matter of local configuration.
> NEW
> In a similar way to [RFC4860], the Aggregator can detect flows
> based on policy
> (not defined in this document) rather than using e2e RSVP flow
> signalling. Then
> it can map them onto aggregate reservations and set the DSCP of
> the packets of
> these flows as they pass into the aggregation region.



Georgios: The above mentioned paragraph is deleted completely from the draft!



>
> Section 1.1. Terminology
>
> " Ingress-egress-aggregate (IEA):
> [...]
> combination of (1) fields), (2) IP addresses of the
> "
> Some text appears to be missing here.
>
> Section 1.1. Terminology
> OLD:
> t-recvFail
> An ingress-egress-aggregate timer that is used at
> The Decision point (in this document at the PCN-
> ingress-node) which when expires raises an alarm to
> management, and activates the PCN-ingress-node to
> block the admission of new PCN-flows. This timer
> expires when it value is equal to T-fail and is
> reset when a report, i.e., RSVP aggregated RESV
> message, is received for a RSVP generic aggregated
> reservation (which is matched to one
> ingress-egress-aggregate).
> NEW:
> t-recvFail
> A timer per ingress-egress-aggregate that the
> PCN-ingress-node
> sets every time it receives an RSVP RESV message for that
> ingress-egress-aggregate. When its value reaches T-fail
> it is assumed that the PCN-ingress has lost
> contact with the
> PCN-egress. Therefore the PCN-ingress blocks
> admission of new
> PCN-flows into that aggregate and raises a
> management alarm.
> REASONING:
> The order in which the clauses were written made it hard to
> understand, there was nothing to say what it measured, and it wasn't
> clear what scope was implied by "it blocks PCN-flows".



Georgios: Done! Please note that we also replaced “RSVP RESV” with “RSVP Aggregated RESV”.



>
> Section 1.1 Terminology
>
> Underscores (e.g t_meas) are often used in the terminology section,
> whereas hyphens (e.g. t-meas) are used in the body text.



Georgios: Done!



>
> Section 2.1 Overview
>
> There is no Section 2.2, so all the sub-sections of 2.1.X could be promoted.



Georgios: Done!



>
> Section 2.1.1
> s/used, SHOULD/used SHOULD/



Georgios: Done!



>
> Section 2.1.2.
> OLD:
> The PCN-traffic is marked using PCN-marking and is classified using
> The PCN-BA (i.e., combination of the DSCP and ECN fields).
> NEW:
> The PCN-ingress marks a PCN-BA useing PCN-marking (i.e.,
> combination of the DSCP and ECN fields), which interior nodes use to
> classify PCN-traffic.
> REASONING:
> Avoid passive verbs - ambiguous.



Georgios: Done!



>
> Section 2.1.3
> s/for the determination of/to determine the address of/

Georgios: Done!



>
> Section 2.1.4
> " o) PCN-ingress-node MUST use one or more policies to estimate whether
> an e2e RSVP reservation session associated with an e2e Path
> message that arrives at the external interface of the PCN-ingress-
> node can be mapped onto an existing RSVP generic aggregation
> reservation state.
> "
> This is a straightforward mapping function, it shouldn't involve policy.

> Also mappings are deterministic - the word estimate is wrong.



Georgios: We replaced the words “to estimate” with “to determine”



>
> Section 3.1
> " o) If the timer t-recvFail expires [...]
> o) If the timer t-recvFail does NOT expire [...]
> "
> Switch the order of these two bullets, to describe the normal
> (successful) behaviour first.



Georgios: Done!



>
> Section 3.1
>
> s/ingress-egress-aggregated/
> /ingress-egress-aggregate/
> s/then (1)/
> /(1)



Georgios: Done!



> [However, I suggest earlier that the technical sense should be
> substantially changed, possibly making these editorial changes irrelevant.]
>
> Section 3.8.
> OLD:
> The PCN object is specified in
> this document and is used for the report of the data measured by
> the PCN-egress-node, for a particular ingress-egress-aggregate,
> see [RFC6661], and [RFC6662].
> NEW:
> The PCN-egress-node reports the marking probabilities it measures for
> a particular ingress-egress-aggregate in a PCN object, as specified in
> Section 4 (see also [RFC6661], and [RFC6662]).
> REASONING:
> Poor sentence order.



Georgios: Done! Re-edited!



>
> Section 3.11.
> s/associated to one ingress-egress-aggregate/
> /associated with one ingress-egress-aggregate/



Georgios: Done!



>
> Section 3.15
> Repeats Section 2.1.9. Unnecessary.



Georgios: The context of the two sections is slightly different! Therefore, I would like to leave them!



>
> Section 4.
> s/by an PCN-egress node/
> /by a PCN-egress node/



Georgios: Done!



Best regards,
Georgios