[Pce] Benjamin Kaduk's Discuss on draft-ietf-pce-lsp-control-request-09: (with DISCUSS and COMMENT)
Benjamin Kaduk via Datatracker <noreply@ietf.org> Mon, 30 September 2019 17:49 UTC
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Date: Mon, 30 Sep 2019 10:49:04 -0700
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Subject: [Pce] Benjamin Kaduk's Discuss on draft-ietf-pce-lsp-control-request-09: (with DISCUSS and COMMENT)
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Benjamin Kaduk has entered the following ballot position for draft-ietf-pce-lsp-control-request-09: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-pce-lsp-control-request/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- This may just be a philosophical discussion, but if RFC 8231 marks the PLSP-ID value of 0 as "reserved" and we are making use of the extension point, do we need to have an Updates: relationship with 8231? This seems particularly poigniant given that we have to explicitly override the RFC 8231 error handling, with some text in the second paragraph of Section 4. What kind of feature negotiation is available to check support prior to using this flag? After all, if the peer does not implement this document it will not implement the override of 8231 error handling and will respond with errors when the D flag is set (or the PLSP-ID of 0 used). If we have to just "try it and fall back to not using it if we get errors", that has some associated security considerations as well. What can we say about authorization policy on the PCC? Alvaro touched on this in his Comment, but I think it's important enough to be Discuss-level. Since this policy is the key factor to the security posture of this extension, not only does it seem like there MUST be the ability to configure the policy, but it also seems like we should be able to give some guidance on typical use cases (where the authors believe the security properties to be reasonable). Other use cases might require an additional level of analysis by those proposing to deploy the solution. ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- Section 1 It includes mechanisms to effect LSP state synchronization between Path Computation Clients (PCCs) and PCEs, delegation of control of LSPs to PCE, and PCE control of timing and sequence of path computations within and across PCEP sessions. [...] nit: assuming this is grouped as "it includes mechanisms to: (1) effect LSP state synchronization [...], (2) delegation of control [...], and (3) PCE control of timing and sequence [...]", the verb tenses need to be changed so that they match up. For Redundant Stateful PCEs (section 5.7.4. of [RFC8231]), during a PCE failure, one of the redundant PCE could request to take control over an LSP. The redundant PCEs may use a local policy or a Just to check: this request is only possible with the mechanism defined in this document, and is not possible with just the previous technologies? I might suggest to s/could/might want to/ to make it more clear that this is motivating the rest of the document. In case of virtualized PCEs (vPCE) running as virtual network function (VNF), as the computation load in the network increases, a nit: singular/plural mismatch "PCEs"/VNF can be used in conjunction to [RFC8231]. Ultimately, it is the PCC that decides which PCE to delegate the orphaned LSP. nit: either "to which to delegate the orphaned LSP" or "to delegate the orphaned LSP to". Section 3 A new flag, the "LSP-Control Request Flag" (C), is introduced in the SRP object. On a PCUpd message, a PCE sets the C Flag to 1 to indicate that it wishes to gain control of LSPs. The LSPs are identified by the LSP object. A PLSP-ID of value other than 0 and 0xFFFFF is used to identify the LSP for which the PCE requests control. The PLSP-ID value of 0 indicates that the PCE is requesting control of all LSPs originating from the PCC that it wishes to delegate. [...] nit: I suggest s/identified by the LSP object/identified by the PLSP-ID in the LSP object following the SRP object/. delegate. The C Flag has no meaning in other PCEP messages that carry SRP object and the flag MUST be set to 0 on transmission and MUST be ignored on receipt. nit: I suggest s/object/objects/ and s/and the/and for which the/ Section 4 If a PCE wishes to gain control over an LSP, it sends a PCUpd message with C Flag set to 1 in SRP object. The LSP for which the PCE requests control is identified by the PLSP-ID. The PLSP-ID of 0 nit: as above, I suggest s/identified by the PLSP-ID/identified by the PLSP-ID in the associated LSP object/ timer. A PCE ignores the C Flag on the PCRpt message. Note that, if nit: I think this is now redundant with the text added in respone to the genart review ("The C Flag has no meaning in other PCEP messages that carry SRP object and the flag MUST be set to 0 on transmission and MUST be ignored on receipt"). It should be noted that a legacy implementation of PCC, that does not support this extension would trigger the error condition as specified in [RFC8231] (a PCErr with Error-type=19 (Invalid Operation) and error-value 1 (Attempted LSP Update Request for a non-delegated LSP)) I don't understand this sentence -- what does "as the D Flag would be unset" mean? Does it just mean that the PCC treats it as unset because it has no code to handle the D flag at all? Section 6 Please cite RFC 7525 as BCP 195.
- [Pce] Benjamin Kaduk's Discuss on draft-ietf-pce-… Benjamin Kaduk via Datatracker
- Re: [Pce] Benjamin Kaduk's Discuss on draft-ietf-… Dhruv Dhody
- Re: [Pce] Benjamin Kaduk's Discuss on draft-ietf-… Benjamin Kaduk
- Re: [Pce] Benjamin Kaduk's Discuss on draft-ietf-… Dhruv Dhody