RE: [Pce] Update on draft-ietf-pce-policy-enabled-path-comp

[Lou Berger <[e-mail]>]

Christian,
         Much thanks for the detailed 
comments.  We'll incorporate changes in the next rev.

BTW one theme in your comments seems to come for 
the style of section 2 staying at a higher level 
(trying to focus on what can be done) and the 
later sections getting into more of the details, 
e.g., PEP and PDP functions.  This approach was 
intentional and I'd be surprised if the next rev 
radically departs from this.  That said, I think 
you have many good comments which will result in 
a more readable document once addressed.

Thanks again for the input,
Lou


At 07:47 AM 10/9/2007, JACQUENET Christian RD-DDEV-REN wrote:

>Dear all,
>
>Please find herein my comments, which are *not* 
>on behalf of the IPSF - only personal :-)
>
>1. General:
>I think this is a very useful document that 
>clearly identifies the advantages of 
>policy-based path computation management in PCE 
>environments. Nevertheless, I would encourage a 
>refined organization of the document, which 
>would distinguish between the framework (current 
>sections 2.1, 4 and 5 basically), the 
>requirements (section 3, but also part of the 
>text that relates to scenarios) and use cases or 
>scenarios (sections 2.2.x, a bit of sections 7 and 8).
>
>2. Section 2.1, page 5:
>The introductory sentence of the third paragraph 
>implicly indicates that PCE may very well behave 
>as either a PDP (makes decisions to be applied 
>by PCC clients for example) or a PEP (applies 
>decisions possibly made by PCC clients and/or 
>other PCE components). I think this is one of 
>the very key notions introduced by this draft, 
>and would therefore suggest an introductory 
>section that would elaborate on this heuristic, 
>possibly after the reminder about basic concepts of policy-based management.
>
>3. Section 2.1, page 6:
>The last sentence of the first paragraph is 
>slightly confusing: I don't think the "or" is 
>exclusive, that is, provider-defined policies might very well be real time.
>
>4. Section 2.2.3, page 11:
>What's a policy-enabled PCC? A PCC that either 
>embeds a PEP, a PDP or both? I think this should 
>be elaborated, possibly in the Terminology 
>section. Note also that the last sentence of the 
>page mixes the notions of "making decision" and 
>"apply user or service-specific policies": since 
>the text introduces a kind of causality effect 
>(the PEP embedded in the PCC enforces user or 
>service-specific policies, which seems to result 
>in soliciting the PDP embedded in the PEP to 
>make decisions about the scope of constraints 
>that need to be taken into account for path 
>computation purposes), I would suggest a kind of 
>flow diagram that could possibly elaborate on the corresponding chronology.
>
>5. Section 2.2.3, page 12:
>Related to the comment above, the sentence "when 
>deciding…" of the first paragraph may also 
>suggest the activation of a LPDP capability. I 
>would also elaborate on the possible 
>interactions between the PEP, the PDP and the 
>possible LPDP capabilities that may be embedded 
>in the PCC, assuming a differentiation "a la 
>COPS Client-Type". Who's the destinee of the 
>path computation request in the "once the 
>constraints…" sentence of the same paragraph - 
>the PCE? In the third paragraph, it seems that 
>(1) The PCC embeds a PDP that makes decisions 
>about constraint-defined policies, (2) Sends a 
>path computation request that conveys the 
>aforementioned policy information towards the 
>PCE, whose embedded PEP (3) Applies the 
>corresponding decisions: is this statement 
>correct? If so, I don't understand why the PCE 
>may "decide to reject the request": that is, 
>from a policy management standpoint, only the 
>PEP of the PCE is solicited in this context, 
>which means that the PEP may not be capable of 
>enforcing the decision, but I don't think the 
>PEP is entitled to *reject* the decision, as 
>part of a decision making process. Maybe it's a 
>wording issue. What would be the conditions to 
>send path computation requests to more than one 
>PCE, aside from an inter-domain context? I'm not 
>sure I understand why the response sent by the 
>PCE-PEP back to the requesting PCC-PDP may 
>indicate *policies*. Unless the document refers 
>to a kind of PCE-inferred feedback PIB (RFC 
>3571)? In that case, I would elaborate.
>
>6. Section 3, page 15:
>The notion of trusted nodes (as introdcued in 
>the third paragraph) should deserve some 
>elaboration, IMHO. The security considerations 
>of this page should either be extended (e.g. 
>preservation of the confidentiality of the 
>information that will be exchanged between a PDP 
>and a set of PDPs), or reference the "true" 
>Security Considerations section of the document, 
>which BTW, rightfully elaborates on such issues.
>
>7. Section 5, page 18:
>I don't understand why a protocol like COPS 
>couldn't be used in the case where PEP and PDP 
>are colocated. In any case, a protocol is 
>required to convey the exchanges between the PEP 
>and the PDP… In addition (last line of the 
>page), it's very unlikely that SNMP will be used 
>to retrieve information from a PIB.
>
>8. Section 5, page 19:
>I would suggest some elaboration on the kind of 
>information any given PEP (PCC or PCE) may 
>receive from another *PEP* - is this a typo 
>(i.e. read PDP instead), or does this relate to 
>information different from "policy-related" 
>information or else? In a COPS context, multiple 
>Client-Types can certainly reside and coexist 
>within a PEP, but I'm not sure I understand why 
>PEPs would exchange information. Also, the 
>following paragraph ("any given policy…") is a 
>bit confusing to me: I don't understand this 
>notion of partial interpretation, and would 
>rather suggest another wording - enforcement 
>instead of interpretation. Besides, I'm not sure 
>this paragraph helps in understanding the roles played by PEPs and PDPs.
>
>9. Section 6.1., page 20:
>Why *all* PC policy types used in the net *must* 
>be applied? It's a "Client-Type" specific thing, IMHO.
>
>10. Section 6.1., page 21:
>In the first paragraph, I don't understand why 
>the PCE selection should be static. Even if the 
>policy enforcement is restricted to the PCE (for 
>path computation purposes), nothing prevents a 
>PEP embedded in a PCC to support the relevant 
>"Client-Type", hence yielding the dynamic 
>identification of the corresponding PCE, by 
>means of the COPS-like OPEN message at PCC 
>bootstrap, for example. In the third paragraph, 
>the "must" of the first sentence is too strong, 
>IMHO, unless the sentence means that any kind of 
>policy must "encouarge" the support of the 
>corresponding "Client-Types" in the PCC-PEP. If so, I would rephrase.
>
>11. Section 6.2., page 22:
>I don't understand why matching repositories 
>would result in a single PC repository, unless 
>further elaboration on such match is provided.
>
>12. Section 6.3, page 23:
>Does the figure relate to PCE instead of PCC (same for figure 12)?
>
>13. Section 7.1., page 25:
>What's an "objection function"?
>
>14. Typos:
>TED = Traffic Engineering Database? SRLG = 
>Shared Risk Link Group? Page 16, provide the 
>normative reference associated to LDAPv3. Page 
>17, remove the "s" of the very last word of the page.
>
>Cheers,
>
>Christian.
>
>
>----------
>De : JP Vasseur [mailto:[e-mail]]
>Envoyé : lundi 8 octobre 2007 22:36
>À : [e-mail]; Lou Berger; Igor Bryskin; 
>Dimitri Papadimitriou; [e-mail]
>Cc : Thomas Walsh; JACQUENET Christian RD-DDEV-REN
>Objet : Fwd: [Pce] Update on draft-ietf-pce-policy-enabled-path-comp
>
>Dear WG,
>
>Christian Jacquenet on behalf of IPSphere 
>proposed to make several comments on this document.
>Christian, could you please send them to the list ?
>
>As agreed, we're still planning to issue a WG LC 
>after this round of discussion.
>
>Thanks.
>
>JP.
>
>Begin forwarded message:
>
>>From: JP Vasseur <<mailto:[e-mail]>[e-mail]>
>>Date: September 18, 2007 2:10:12 PM EDT
>>To: <mailto:[e-mail]>[e-mail], Lou 
>>Berger 
>><<mailto:[e-mail]>[e-mail]>, 
>>Igor Bryskin 
>><<mailto:[e-mail]>[e-mail]>, 
>>  Dimitri Papadimitriou 
>><<mailto:[e-mail]>[e-mail]>, 
>><mailto:[e-mail]>[e-mail]
>>Cc: Thomas Walsh 
>><<mailto:[e-mail]>[e-mail]>, 
>>  JACQUENET Christian RD-TCH-REN 
>><<mailto:[e-mail]>[e-mail]>
>>Subject: [Pce] Update on draft-ietf-pce-policy-enabled-path-comp
>>
>>Dear WG,
>>
>> From the WG minutes of the IETF-69 meeting:
>>
>>12) Update on Policy-Enabled Path Computation Framework
>>draft-ietf-pce-policy-enabled-path-comp-01.txt (Lou - 5mn) [110]
>>
>>Lou> ready for Last Call
>>JP> It sounds ready. Suggestion: offer IPSphere 
>>to have a look at the doc before last call. JP will be the point
>>of contact. Asked Ross whether this is a good 
>>idea, and Ross agreed. Once comments are received, last call.
>>Adrian> OK, but this is not an indefinite 
>>consultation. We want to be able to move ahead and complete the I-D
>>relatively soon.
>>
>>We have contacted IPSphere and RA WG of 
>>IPSphere should provide us some feed-back by
>>mid-October. I have copied Tom Walsh and 
>>Christian Jacquenet (chair of the RAWG) IPSphere.
>>
>>Thanks.
>>
>>JP.
>>_______________________________________________
>>Pce mailing list
>><mailto:[e-mail]>[e-mail]
>>https://www1.ietf.org/mailman/listinfo/pce



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