Re: [CCAMP] AD review of draft-ietf-ccamp-oam-configuration-fwk
Attila Takacs <Attila.Takacs@ericsson.com> Mon, 02 December 2013 06:17 UTC
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From: Attila Takacs <Attila.Takacs@ericsson.com>
To: "adrian@olddog.co.uk" <adrian@olddog.co.uk>, 'CCAMP WG' <ccamp@ietf.org>
Thread-Topic: [CCAMP] AD review of draft-ietf-ccamp-oam-configuration-fwk
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Date: Mon, 02 Dec 2013 06:17:23 +0000
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Subject: Re: [CCAMP] AD review of draft-ietf-ccamp-oam-configuration-fwk
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Hi Adrian, all, Thanks for the review! We have updated the document to address your comments. You can also find below the updates we have made to resolve your comments, look for [at]. Thanks, Attila -----Original Message----- From: CCAMP [mailto:ccamp-bounces@ietf.org] On Behalf Of Adrian Farrel Sent: Monday, November 18, 2013 2:30 PM To: draft-ietf-ccamp-oam-configuration-fwk.all@tools.ietf.org Cc: 'CCAMP WG' Subject: [CCAMP] AD review of draft-ietf-ccamp-oam-configuration-fwk Thank you for this document. I think it is well written and clear. It is very nearly ready to be advanced for publication, but we need to do a little work on the IANA section to make it completely clear for IANA. I suggest the following, but please review it carefully because I have introduced new material that you did not have in your original text. I also have some smaller nits and editorial comments, and a few places where it would be really helpful to clarify the text. I've moved the I-D status to show I expect to see a revision, but please discuss these points with me if you like. Thanks for the work. Adrian === OLD 5. IANA Considerations Two bits ("OAM Alarms Enabled" (O) and "OAM Flows Enabled" (M)) needs to be allocated in the ADMIN_STATUS Object. Two bits ("OAM MEP entities desired" and "OAM MIP entities desired") needs to be allocated in the LSP Attributes Flags Registry. This document specifies one new TLV to be carried in the LSP_ATTRIBUTES and LSP_REQUIRED_ATTRIBUTES objects in Path and Resv messages: OAM Configuration TLV. One new Error Code: "OAM Problem" and a set of new values: "MEP establishment not supported", "MIP establishment not supported", "Unsupported OAM Type", "Configuration Error", "OAM Type Mismatch" and "Unsupported OAM Function" needs to be assigned. IANA is requested to open a new registry: "RSVP-TE OAM Configuration Registry" that maintains the "OAM Type" code points, an associated sub-TLV space, and the allocations of "OAM Function Flags" within the OAM Configuration TLV. RSVP-TE OAM Configuration Registry OAM Type Description ------------ ------------------ 0-255 Reserved Sub-TLV Type Description ------------ ------------------------------------ 0 Reserved 1 OAM Function Flags Sub-TLV 2-31 Reserved for generic Sub-TLVs 32- Reserved for technology specific Sub-TLVs OAM Function Flag bit# Description ---------------------- ------------------------------- 0 Continuity Check (CC) 1 Connectivity Verification (CV) 2 Fault Management Signal (FMS) 3 Performance Monitoring/Loss (PM/Loss) 4 Performance Monitoring/Delay (PM/Delay) 5 Performance Monitoring/Throughput Measurement (PM/Throughput) 6- Reserved NEW 5. IANA Considerations 5.1. ADMIN_STATUS Object Bit Flags IANA maintains a registry called "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Parameters" with a sub-registry called "Administrative Status Information Flags". IANA is requested to allocate two new flags as follows: Bit Number | Hex Value | Name | Reference -----------+------------+--------------------------+---------------- TBA | TBA | OAM Alarms Enabled (O) | [This.ID] TBA | TBA | OAM Flows Enabled" (M) | [This.ID] 5.2. LSP Attributes Flags IANA maintains a registry called "Resource Reservation Protocol- Traffic Engineering (RSVP-TE) Parameters" with a subregistry called "Attribute Flags". IANA is requested to allocate two new flags as follows: Bit | Name | Attribute | Attribute | RRO | Ref No | | Flags Path | Flags Resv | | ----+--------------------------+------------+------------+-----+----- TBA | OAM MEP entities desired | Yes | No | Yes | TBA | OAM MIP entities desired | Yes | No | Yes | 5.3. New LSP Attributes IANA maintains a registry called "Resource Reservation Protocol- Traffic Engineering (RSVP-TE) Parameters" with a subregistry called "Attributes TLV Space" IANA is requested to allocate one new TLV type as follows: Type | Name | Allowed on | Allowed on | Ref | | LSP_ATTRIBUTES | LSP_REQUIRED_ | | | | ATTRIBUTES | -----+-----------------------+----------------+---------------+------ TBA | OAM Configuration TLV | Yes | Yes | 5.4. RSVP Error Code IANA maintains a registry called "Resource Reservation Protocol (RSVP) Parameters" with a subregistry called "Error Codes and Globally-Defined Error Value Sub-Codes". IANA is requested to allocate one new Error Code as follows: Error Code | Meaning | Reference -----------+-------------+------------- TBA | OAM Problem | [This.ID] The value is to be selected from the range 0-239. The following Error Value sub-codes are defined for this new Error Code as follows: Value | Description | Reference ------+---------------------------------+-------------- 1 | MEP establishment not supported | [This.ID] 2 | MIP establishment not supported | [This.ID] 3 | Unsupported OAM Type | [This.ID] 4 | Configuration Error | [This.ID] 5 | OAM Type Mismatch | [This.ID] 6 | Unsupported OAM Function | [This.ID] 5.5. RSVP-TE OAM Configuration Registry IANA is requested to create a new registry called "RSVP-TE OAM Configuration Registry". IANA is requested to create sub-registries as defined in the following subsections: 5.5.1. OAM Types Sub-Registry IANA is requested to create the "OAM Types" sub-registry of the "RSVP-TE OAM Configuration Registry" as follows: Range | Registration Procedures -------+------------------------- 0-255 | IETF Review There are no initial values in this registry. IANA should show the registry as follows: OAM Type Number | OAM Type Description | Reference ----------------+----------------------+-------------- 0-255 | Not allocated | 5.5.2. OAM Sub-TLVs Sub-Registry IANA is requested to create the "OAM Sub-TLVs" sub-registry of the "RSVP-TE OAM Configuration Registry" as follows: Range | Purpose | Registration Procedures -------------+------------------------------|------------------------ 0-31 | Generic Sub-TLVs | IETF Review 32-65534 | Technology-specific Sub-TLVs | IETF Review 65535-65536 | Experimental Sub-TLVs | Experimental IANA is requested to populate the registry as follows: Sub-TLV Type | Description | Reference -------------+----------------------------+------- 0 | Reserved | [This.ID] 1 | OAM Function Flags Sub-TLV | [This.ID] 2-31 | Not allocated | 32-65534 | Not allocated | 5.5.3. OAM Function Flags Sub-Registry IANA is requested to create the "OAM Function Flags Sub-Registry" sub-registry of the "RSVP-TE OAM Configuration Registry". New values in the registry are allocated by "IETF Review". There is no top value to the range. Bits are counted from bit 0 as the first bit transmitted. IANA is requested to populate the registry as follows. OAM Function Flag | Description bit number | ------------------+--------------------------------------------- 0 | Continuity Check (CC) 1 | Connectivity Verification (CV) 2 | Fault Management Signal (FMS) 3 | Performance Monitoring/Loss (PM/Loss) 4 | Performance Monitoring/Delay (PM/Delay) 5 | Performance Monitoring/Throughput Measurement | (PM/Throughput) 6-... | Not allocated END [at] Thanks, I have updated the IANA section with the suggested text. --- Please expand OAM and LSP in the Abstract. [at] Done. --- In Section 3 you have some terms defined (MP, ME, MIP, MEP). Some of these terms are consistent with the use of terms in draft-ietf-mpls-tp- rosetta-stone and some are not. Is there a specific reason why you have diverged from this other draft? If not, you should align this work. [at] Aligned to rosetta-stone --- Section 3.1 When using the GMPLS control plane, establishment and enabling of OAM functions MUST be bound to RSVP-TE message exchanges. I think you mean... When using the GMPLS control plane for both LSP establishment and to enable OAM functions on the LSPs, the control of both processes is bound to RSVP-TE message exchanges. [at] Thanks, changed to the suggested text. --- Section 4.1 If the "OAM MEP entities desired" bit is set it is indicating that the establishment of OAM MEP entities are required at the endpoints of the signaled LSP. If the establishment of MEPs is not supported an error MUST be generated: "OAM Problem/MEP establishment not supported". I can see how this works for an implementation of this document that chooses not to (or cannot) support OAM on a given LSP. I do not understand how it works when a node that does not support this document receives the "OAM MEP entities desired" bit set - it cannot return the desired response because it doesn't support this document. To handle this, I think you need to split the two cases. 1. Does not support the establishment of MEPs on this specific LSP 2. Does not support any establishment of MEPs. In the second case you need to determine how this will be made to work. Since 5420 specifies that the unknown bit in an LSP_ATTRIBUTE object will be silently ignored, you need to use the absence of a positive acknowledgement to indicate to the ingress that the function is not supported. See also Section 4.4. [at] The use of OAM Configuration information in the Resv message is described in Section 3. To clarify the operation in the above case I have added the following paragraph to Section 3.1: In case an egress LSR does not support the extensions defined in this document, according to RFC5420, it will silently ignore the new LSP Attributes Flags as well as the TLVs carrying additional OAM configuration information, and therefore no error will be raised that would notify the ingress LSR about the missing OAM configuration actions on the egress side. However, as described above, an egress LSR conformant to the specification of this document will set the LSP Attributes Flags and include the OAM Configuration TLV in the Resv message indicating the configuration of the OAM mechanisms, therefore an ingress LSR by detecting the missing information in the Resv message will be able to recognize that the remote end does not support the OAM configuration functionality and therefore it SHOULD tear down the LSP, and if appropriate signal the LSP without any OAM configuration information. --- Section 4.1 This bit MUST only be set if the "OAM MEP entities desired" bit is set. This is a rather unusual construction. I think you may mean... If the "OAM MEP entities desired" bit is not set then this bit MUST NOT be set. [at] Thanks, changed to the suggested text. --- Section 4.1 If the establishment of a MIP is not supported an error MUST be generated: "OAM Problem/MIP establishment not supported". Exactly the same problem as described for "OAM MEP entities desired" above except for the additional behavior if used on LSP_REQUIRED_ATTRIBUTES. (See also 4.4) [at] I added the following clarification. If an intermediate LSR does not support the extensions defined in this document it will not recognize the "OAM MIP entities desired" flag and although the LSP_REQUIRED_ATTRIBUTES object was used it will not configure MIP entities and will not raise any errors. If LSRs that are not supporting this document are to be assumed in the network, the ingress LSR SHOULD collect per-hop information about the LSP Attributes utilizing the LSP Attributes sub-object of the Record Route Object as defined in RFC5420. When the Record Route object is received the ingress SHOULD check whether all intermediate LSRs set the "OAM MIP entities desired" flag indicating support of the function, if not, depending on operator policy the LSP MAY need to be torn down. </t> --- Section 4.2 Type: indicates a new type: the OAM Configuration TLV (3) (IANA to assign). If this is a specific request that the value 3 is assigned, you should reflect this in Section 5. [at] removed "(3)" --- Section 4.2 When carried in the LSP_ATTRIBUTES Object, intermediate nodes not supporting the OAM Type pass the object forward unchanged as specified in [RFC5420], and only Label Edge Nodes MUST generate an error if the OAM Type is not supported at the LSP end-point. There are a couple of issues here. You have defined a "Label Edge Node". You also have another "only MUST" construction. How about... When carried in the LSP_ATTRIBUTES Object, intermediate nodes not supporting the OAM Type pass the object forward unchanged as specified in [RFC5420]. Ingress and egress nodes that support the OAM Configuration TLV but that do not support a specific OAM Type MUST respond with an error indicating "OAM Problem/Unsupported OAM Type". [at] Thanks, changed to the suggested text. --- Section 4.2 Can multiple copies of the OAM configuration TLV be present in one LSP_ATTRIBUTES object? [at] Only one, changed text: OLD The OAM Configuration TLV MAY be carried in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES object in Path and Resv messages. NEW One OAM Configuration TLV MAY be carried in the LSP_ATTRIBUTES or LSP_REQUIRED_ATTRIBUTES object in Path and Resv messages. --- I think section 4.2 needs to mention the generic sub-TLVs. Reading the text as it stands, it appears that all sub-TLVs are for technology- specific OAM. So you need: - To explain generic sub-TLVs so that future sub-TLVs can be defined - To include a forward pointer to 4.2.1 [at] added the following paragraph for clarification. Two groups of TLVs are defined: generic sub-TLVs and technology specific sub-TLVs. Generic sub-TLVs carry information that are applicable independent of the actual OAM technology, while technology specific sub-TLVs are providing configuration parameters for specific OAM technologies. This document defines one generic sub-TLV, see Section 4.2.1, while it is foreseen that technology specific sub-TLVs will be defined by separate documents. --- Section 4.2.1 As the first sub-TLV the "OAM Function Flags Sub-TLV" MUST always be included in the "OAM Configuration TLV". I think you mean: The "OAM Configuration TLV" MUST always include a single instance of the "OAM Function Flags Sub-TLV" and it MUST always be the first sub- TLV. [at] Thanks, changed to the suggested text. --- Section 4.2.1 You need to reiterate that the Length field counts octets (because for a variable length bitmap someone might easily think it is a count of bits) and then you need to explain how to set the length field and how to handle padding. [at] Added the text below. The TLV is padded to 4-octet alignment. The Length field indicates the size of the padded TLV in octets. --- Section 4.2.2 One technology specific sub-TLV MAY be defined for each "OAM Type". This sub-TLV MUST contain any further OAM configuration information for that specific "OAM Type". The technology specific sub-TLV, when used, MUST be carried within the OAM Configuration TLV. IANA is requested to maintain the OAM technology specific sub-TLV space in the new "RSVP-TE OAM Configuration Registry". The use of 2119 language here is odd. It is really meant for implementation instructions, not to constrain future specifications. How about saying: If technology-specific configuration information is needed for a specific "OAM Type", then this information is carried in a technology-specific sub-TLV. Such sub-TLVs are OPTIONAL and an OAM Configuration TLV MUST NOT contain more than one technology- specific sub-TLV. IANA is requested to maintain the OAM technology specific sub-TLV space in the new "RSVP-TE OAM Configuration Registry". [at] Thanks, changed to the suggested text. --- Section 4.3 s/are allocated by this draft/are allocated by this document/ [at] done. --- Section 4.3 When the "OAM Flows Enabled" bit is set, OAM packets are sent; if it is cleared, no OAM packets are emitted. When the bit is sent, is that MAY, SHOULD, or MUST send OAM packets? If clear, I think that is MUST NOT be sent. Why do you say "OAM packets"? Doesn't this I-D apply to all OAM mechanisms? [at] Changed to "When the "OAM Flows Enabled" bit is set, OAM mechanisms MUST be enabled; if it is cleared, OAM mechanisms MUST be disabled." --- Section 4.3 When the "OAM Alarms Enabled" bit is set OAM triggered alarms are enabled and associated consequent actions are executed including the notification to the management system. When this bit is cleared, alarms are suppressed and no action is executed and the management system is not notified. I understand "When this bit is cleared, alarms are suppressed" and "the management system is not notified", but I don't understand "no action is executed." If there is no action on OAM detecting some issue, then why run OAM? There is clearly something you had in mind when you created two separate admin statuses, but the purpose is not clear in your document. [at] The operation and use of these two bits are described in Section 3. To highlight this I added a note saying: "For a detailed description of the use of these flags see Section 3." _______________________________________________ CCAMP mailing list CCAMP@ietf.org https://www.ietf.org/mailman/listinfo/ccamp
- [CCAMP] AD review of draft-ietf-ccamp-oam-configu… Adrian Farrel
- Re: [CCAMP] AD review of draft-ietf-ccamp-oam-con… Attila Takacs