Subject: Re: [mpls] MIB Doctor Review of draft-ietf-mpls-tp-oam-id-mib-02.txt

From: venkatesan mahalingam <[email-masked]>
Date: Sat, 20 Apr 2013 14:10:51 -0700

Joan,

Please find below my comments with the tag VM>. We will publish the new
version of this draft soon.

-Venkat.

On Mon, Mar 11, 2013 at 8:34 PM, Joan Cucchiara
<[email-masked]>wrote:

>
> Authors,
>
> Most of the comments during the LC have been addressed.
> Thank you for that.   Please see some follow-up comments below.
>
> Thanks,
> -Joan
>
>
>
>
> * MIB compiles cleanly with smicng and smilint
>
>
> Specific Comments:
> ====================
>
> Section 3.3 Acronyms
>
>
> * MIP is specified slightly differently in the referenced docs.
> Please be consistant.
>
VM> OK.

>
>
> Section 6.
>
> This example, specifies the mplsOamIdMeMpEntry as a MEP, but why
> isn't the SourceMepIndex or SinkMepIndex == mplsOamIdMeMpIndex?
>
> Also, there are at least 2 MEPs in an ME, and at least one ME
> in a MEG and these relationships are not completely evolved
> in this example.  I think the example should be expanded
> to agree with what is stated in the first paragraph.
>
> VM> OK, the example will be expanded to represent MEG->ME->Source/Sink
MEPs clearly.
As per this MIB module,
MEG->ME->MPIndex([Source and Sink MEP] or MIP index)
For example,

If we have multiple MEPs in a single ME within an MEG node.
MEG index - 1
ME index - 1
MP index - 1 (Source and Sink MEPs1)
MP index - 2 (Source and Sink MEPs2)

*Entry-1:*
ME Table - 1,1,1
mplsOamIdMeSourceMepIndex - 2
mplsOamIdMeSinkMepIndex - 3

*Entry-2:*
ME Table - 1,1,2
mplsOamIdMeSourceMepIndex - 4
mplsOamIdMeSinkMepIndex - 5

*MIP entry:*

MEG index - 1
ME index - 1
MP index - 3 (MIP index)
ME Table - 1,1,3
mplsOamIdMeMpIfIndex - MPLS incoming/outgoing interface.

> MIB Module comments
> -------------------
>
> * TC:  MplsOamPhbTCValue
>
>
>         MplsOamPhbTCValue ::= TEXTUAL-CONVENTION
>            STATUS              current
>            DESCRIPTION
>                "This is the Per-hop Behavior (PHB) traffic class values
>                 for the MPLS OAM operations."
>            SYNTAX        INTEGER {
>                            be (1),
>                            af1 (2),
>                            af2 (3),
>                            af3 (4),
>                            af4 (5),
>                            ef (6),
>                            cs6 (7),
>                            cs7 (8)
>                          }
>
> VM> As MPLS header traffic class (TC) field has only 3 bits, we derived
the above TC values (8 possible values to represent it in 3 bits) from the
below TC values.

> Rfc3270, "Multi-Protocol Label Switching (MPLS) Support of
> Differentiated Services", specifies that MPLS TP will use DSCP as per
> rfc2474 and other specs.   Is that the intent wrt this TC?
>
> If not, please explain where these values are defined, otherwise,
> if these values are as per rfc3270, then please be consistant with the
> labels.
>
> TC labels should correspond more closely to DiffServ BHB traffic class
> values.
> In other words,
>
> http://www.iana.org/**assignments/dscp-registry/**dscp-registry.xml<http://www.iana.org/assignments/dscp-registry/dscp-registry.xml>
>
>   Name     Space  Reference
>   CS0         000000 [RFC2474]
>   CS1         001000 [RFC2474]
>   CS2         010000 [RFC2474]
>   CS3         011000 [RFC2474]
>   CS4         100000 [RFC2474]
>   CS5         101000 [RFC2474]
>   CS6         110000 [RFC2474]
>   CS7         111000 [RFC2474]
>   AF11        001010 [RFC2597]
>   AF12        001100 [RFC2597]
>   AF13        001110 [RFC2597]
>   AF21        010010 [RFC2597]
>   AF22        010100 [RFC2597]
>   AF23        010110 [RFC2597]
>   AF31        011010 [RFC2597]
>   AF32        011100 [RFC2597]
>   AF33        011110 [RFC2597]
>   AF41        100010 [RFC2597]
>   AF42        100100 [RFC2597]
>   AF43        100110 [RFC2597]
>   EF PHB      101110 [RFC3246]
>   VOICE-ADMIT 101100 [RFC5865]
>
>
> Continuing with that thought: I believe this TC could (and should) be
> formalized into an IANA-Maintained MIB if these values are the same
> as the above IANA-Maintained assignments for DFCPs.
> (NOTE: this was mentioned also in the LC comments.)  Please discuss.
>
> Also, this TC should have a REFERENCE clause.
>
>
>
> * mplsOamIdMegIndex
> There is no information about how to employ mplsOamIdMegIndexNext to
> obtain a value for this index.   Please update the DESCRIPTION accordingly.
>
>
> VM> Edited.

>
> * mplsOamIdMegOperatorType
> Why does this say "should have valid values...", isn't this a MUST?
> Also, s/while making/when/
>
> * mplsOamIdMegIdCc
>
> s/contains non-null ICC/MUST contain a/
>
> s/otherwise null ICC value/otherwise a null ICC value/
>
> s/should be assigned/MUST be assigned/
>
> * mplsOamIdMegIdIcc
>
> Same comments as above.   Please use MUST.
>
> * mplsOamIdMegIdUmc
> Same comments as above.  Please use MUST.
>
>
> VM> Edited.

> * mplsOamIdMegServiceType
> Could you please specify the service pointer by the object's name?
>
> Also, the references are within the DESCRIPTION which is fine, but
> they should also be in a REFERENCE clause.
>
>
> VM> Edited.

> * mplsOamIdMeIndexNext and mplsOamIdMpIndexNext
> These objects are not referred to by mplsOamIdMeIndex or
> mplsOamIdMeMpIndex.
> There is not enough description to understand how the IndexNext objects
> are to be used.
>
> VM> Edited.

>
> * MplsOamIdMeTable
>
> The mplsOamIdMeEntry states "An entry in this table
> represents MPLS-TP maintenance entity."   Yet, looking at the
>              INDEX { mplsOamIdMegIndex,
>                      mplsOamIdMeIndex,
>                      mplsOamIdMeMpIndex
>                    }
>
> This is not an ME because an ME by definition has 2 (source/sink)MEPs.
> An entry in this table represents either a MEP or MIP, not an ME.
>
> VM> Yes, this is not an ME but it contains ME information (MEPs/MIP).
Would it make more sense if we change it to mplsOamIdMeInfoEntry?

>
> *) What is the benefit of combining MEP and MIP (i.e. the objects
> which contain "Mp" as part of their object name)?
> Many other objects in this table, need to figure out if the entry
> is describing a MEP or MIP before the value can be interpreted correctly.
> Additionally, there is duplicate info in the form of having a Source and
> Sink specified for each Mp. Could you elaborate on what the
> benefit is of having listing MEPs and MIPs in this way?
>
> It seems like the original intent may have been to specify an ME
> as being an entry in this table.  However, that would mean the table
> should probably be indexed by MEG index, a ME index, a source MEP index
> and a sink MEP index.
>
> This would  greatly simplify many of the object descriptions.
>
> Have you considered specifying MIPs in a 3rd table, such that each
> ME would have 2 MEPs and zero or more MIPs?
>
> Please discuss.
>
> VM> We thought through all the possible options, it looks like lot of
informations are duplicated unnecessarily if we have the seperate tables
for MEP/MIP configurations. For up/down MEPs configurations, all the
informations in the ME table will be used but for MIP, except the
Source/Sink MEPs objects, all other objects will be used. So, we wanted to
combine MEP/MIP in a single table for better management.

So, we will certainly improvise the existing MEG&ME tables example to
provide all possible configuration options.

>
>
> *) mplsOamIdMeMpIfIndex
>
> Rfc6370, Section 4.discusses an IF_NUM and an IF_ID and states
> "Note that IF_Num had no relation with the ifNum object defined in
> RFC2863.  Further, no mapping is mandated between IF_Num and ifIndex in
> RFC 2863."
>
> I don't see any mention of ifIndex in RFC 6371, so could you tell me what
> Section?   Is this object supposed to represent IF_NUM in rfc6370?
>
VM> Reference should be replaced with rfc-6370 section4.
and RFC2863 should be removed. Good catch. Thanks.

>
> *) mplsOamIdMeServicePointer
>
> The DESCRIPTION contains wording which is very loose.  Could you
> please use wording which specifies a "SHOULD" or "MUST"?
> Under what circumstances should this be 0.0?
>
> VM> Edited.

>
> Compliance Statement of the MIB
>
> *) Compliance (This has been asked before and I have not seen any
> discussion about it.)
>
> There is no read-only compliance. Has it been made clear
> to the WGs (MPLS and PWE3) that SNMP sets will need to
> be supported in order to be compliant with the MIB?
>
> VM> Not yet, sorry for the delay. We will make read-only compliance clear
to WG after this draft submission.

>
> *) question above, about whether the intention is to support
> ifIndex as per rfc2863 or IF_ID (or IF_NUM) as per rfc6370 may
> affect this.
>
>      "MODULE IF-MIB -- The Interfaces Group MIB, RFC 2863.
>      MANDATORY-GROUPS {
>         ifGeneralInformationGroup,
>         ifCounterDiscontinuityGroup"
>
>
> *)    mplsOamIdNotificationObjectsGr**oup  OBJECT-GROUP
>
> I don't see a need to make a specific group for
> these objects.  They are already specified by mplsOamIdGroups.
>
> VM> Edited.

>
> Section 8. Security Section
>
> Need to reference specific read-create objects and also read-only which
> could impact the network.
>
> Additionally, the incomplete sentence:
> "These are the tables and objects and their sensitivity/vulnerability: "
> needs to be completed.
>
> VM> Edited.

>
> Section 9.  IANA Considerations
>
> s/specified this document/specified in this document/
> missing the word "in"
>
>
> VM> Edited.

> Section 11.
> Thank you for the ack!
>
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