Re: [mpls] Alia Atlas' Discuss on draft-ietf-mpls-residence-time-14: (with DISCUSS and COMMENT)

Greg Mirsky <gregimirsky@gmail.com> Thu, 02 March 2017 16:43 UTC

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From: Greg Mirsky <gregimirsky@gmail.com>
Date: Thu, 2 Mar 2017 08:43:19 -0800
Message-ID: <CA+RyBmXjShUFukDK+UZdqsyga+teqCMjc47LXzgR_mJz455=1Q@mail.gmail.com>
To: Alia Atlas <akatlas@gmail.com>
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Cc: mpls-chairs@ietf.org, draft-ietf-mpls-residence-time@ietf.org, "mpls@ietf.org" <mpls@ietf.org>, The IESG <iesg@ietf.org>
Subject: Re: [mpls] Alia Atlas' Discuss on draft-ietf-mpls-residence-time-14: (with DISCUSS and COMMENT)
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Thank you!
Will work on other comments we've received and post the update then.

Regards,
Greg


On Thu, Mar 2, 2017 at 8:40 AM, Alia Atlas <akatlas@gmail.com>; wrote:

> LGTM - thanks!
>
> I'll clear now - assuming you will post the updated draft.
>
> Regards,
> Alia
>
> On Thu, Mar 2, 2017 at 11:37 AM, Greg Mirsky <gregimirsky@gmail.com>;
> wrote:
>
>> Hi Alia,
>> thank you for the proposed text. Accepted. Please see the updated text
>> below.
>>
>> Regards,
>> Greg
>>
>> On Thu, Mar 2, 2017 at 6:48 AM, Alia Atlas <akatlas@gmail.com>; wrote:
>>
>>> Hi Greg,
>>>
>>>
>>>
>>> On Thu, Mar 2, 2017 at 2:01 AM, Greg Mirsky <gregimirsky@gmail.com>;
>>> wrote:
>>>
>>>> Hi Alia,
>>>> thank you for your thorough review and the comments. Please find my
>>>> responses in-line tagged GIM>>.
>>>>
>>>> Regards,
>>>> Greg
>>>>
>>>> On Wed, Mar 1, 2017 at 3:05 PM, Alia Atlas <akatlas@gmail.com>; wrote:
>>>>
>>>>> Alia Atlas has entered the following ballot position for
>>>>> draft-ietf-mpls-residence-time-14: 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/stat
>>>>> ement/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-mpls-residence-time/
>>>>>
>>>>>
>>>>>
>>>>> ----------------------------------------------------------------------
>>>>> DISCUSS:
>>>>> ----------------------------------------------------------------------
>>>>>
>>>>> Thank you for a clear document.  I think that this should be a
>>>>> straightforward Discuss to better clarify.
>>>>>
>>>>> In Section 4.8.1, it says "The RTM Set sub-object contains an ordered
>>>>> list, from egress node to
>>>>>    ingress node, of the RTM capable nodes along the LSP's path." but
>>>>> the
>>>>> sub-TLVs (as most clearly
>>>>> indicated by "4.8.1.3.  Unnumbered Interface Sub-TLV" are actually
>>>>> meant
>>>>> to be a list of interfaces.
>>>>>
>>>> GIM>> I think that the text, e.g. by stating "The Length is always 12" and
>>>> the Figure 10 are clear that only one interface can be listed in the
>>>> sub-TLV.
>>>> And the same is true for other sub-TLVs.
>>>>
>>>
>>> The draft says"Only a single RTM_SET  sub-TLV with the given Value field
>>> MUST be present in the RTM_SET   TLV.  If more than one sub-TLV is found
>>> the LSP setup MUST fail"
>>>
>>> There is nothing there that clearly states that only one of the 3
>>> sub-TLVs should be place in the RTM_SET TLV for a particular node.  There
>>> is also the inaccuracy between putting in interface addresses versus the
>>> claim that it contains nodes.
>>>
>>> For instance, text could be added/changed to indicate:
>>>
>>> "The RTM_SET TLV is intended to include the subset of the RRO Object
>>> that represents those egress interfaces on the LSP that are RTM-capable.
>>> After a node chooses an egress interface to use in the RRO sub-TLV, that
>>> same egress interface, if RTM-capable,  SHOULD be placed into the RTM_SET
>>> TLV using one of the IPv4 sub-TLV, IPv6 sub-TLV, or Unnumbered Interface
>>> sub-TLV.  The address family chosen SHOULD match that of the RESV message
>>> and that used in the RRO; the unnumbered interface sub-TLV is used when the
>>> egress interface has no assigned IP address.  A node MUST NOT place more
>>> sub-TLVs in the RTM_SET TLV than the number of RTM-capable egress
>>> interfaces the LSP traverses that are under that node's control."
>>>
>>> OLD TEXT:
>>
>>    Sub-TLVs are organized as a last-in-first-out stack.  The first -out
>>    sub-TLV relative to the beginning of RTM_SET TLV is considered the
>>    top.  The last-out sub-TLV is considered the bottom.  When a new sub-
>>    TLV is added, it is always added to the top.  Only a single RTM_SET
>>    sub-TLV with the given Value field MUST be present in the RTM_SET
>>    TLV.  If more than one sub-TLV is found the LSP setup MUST fail with
>>    the generation of a PathErr message with the Error Code "Duplicate
>>    sub-TLV" Section 8.9 <https://tools.ietf.org/html/draft-ietf-mpls-residence-time-05#section-8.9> and Error Value contains 16-bit value composed
>>    of (Type of TLV, Type of sub-TLV).
>>
>>
>> NEW TEXT:
>>
>>    Sub-TLVs are organized as a last-in-first-out stack.  The first-out
>>    sub-TLV relative to the beginning of RTM_SET TLV is considered the
>>    top.  The last-out sub-TLV is considered the bottom.  When a new sub-
>>    TLV is added, it is always added to the top.
>>
>>    The RTM_SET TLV is intended to include the subset of the RRO sub-TLVs
>>    that represents those egress interfaces on the LSP that are RTM-
>>    capable.  After a node chooses an egress interface to use in the RRO
>>    sub-TLV, that same egress interface, if RTM-capable, SHOULD be placed
>>    into the RTM_SET TLV using one of the IPv4 sub-TLV, IPv6 sub-TLV, or
>>    Unnumbered Interface sub-TLV.  The address family chosen SHOULD match
>>    that of the RESV message and that used in the RRO; the unnumbered
>>    interface sub-TLV is used when the egress interface has no assigned
>>    IP address.  A node MUST NOT place more sub-TLVs in the RTM_SET TLV
>>    than the number of RTM-capable egress interfaces the LSP traverses
>>    that are under that node's control.  Only a single RTM_SET sub-TLV
>>    with the given Value field MUST be present in the RTM_SET TLV.  If
>>    more than one sub-TLV is found the LSP setup MUST fail with the
>>    generation of a ResvErr message with the Error Code "Duplicate sub-
>>    TLV" Section 7.9 and Error Value contains 16-bit value composed of
>>    (Type of TLV, Type of sub-TLV).
>>
>>
>>
>>> It isn't clear whether these are supposed to be the egress interface, the
>>>>> ingress interface, or just any
>>>>> interface
>>>>
>>>> GIM>> In order for the process described in section 4.8 to work RTM
>>>> node MUST use the same ID in RTM_SET sub-TLV as in RRO subobject.
>>>>
>>>
>>> Right - but I don't see the draft saying that clearly.  See my suggested
>>> text above.
>>>
>>>
>>>> - or why sending just a Router ID wouldn't be sufficient.
>>>>> There is no indication as to whether
>>>>> it is ok to include both the IPv4 and IPv6 address Sub-TLVs for the
>>>>> same
>>>>> node or how to select which one
>>>>> to use.
>>>>>
>>>> GIM>> Selection should follow election of ID for corresponding
>>>> subobject in RRO.
>>>>
>>>
>>> Agreed - see suggested text.
>>>
>>>>
>>>>> ----------------------------------------------------------------------
>>>>> COMMENT:
>>>>> ----------------------------------------------------------------------
>>>>>
>>>>> 1) I am disappointed that the sub-TLV needed for an OSPFv3 Extended LSA
>>>>> isn't defined.  While I understand that a normative reference isn't
>>>>> desirable - instead of "left for future study", it would be better to
>>>>> say
>>>>> that the sub-TLV should use the same format as in Sec 4.3 and that the
>>>>> type allocation and full details are left to a future document.   This
>>>>> is
>>>>> exactly how gaps are created for networks running only IPv6.   If
>>>>> draft-ietf-ospf-ospfv3-lsa-extend-13 were not waiting for
>>>>> implementations
>>>>> and had a clear time-frame for how and when to progress, this would
>>>>> also
>>>>> be a Discuss.
>>>>>
>>>> GIM>> I agree that your proposal narrows the gap for IPv6 extension for
>>>> RTM capability advertisement. Will apply the text you've suggested in the
>>>> next version. Hope OSPF WG agrees to this change.
>>>>
>>>
>>> OLD TEXT:
>>
>>    The capability to support RTM on a particular link (interface) can be
>>    advertised in OSPFv3 using LSA extensions as described in
>>    [I-D.ietf-ospf-ospfv3-lsa-extend <https://tools.ietf.org/html/draft-ietf-mpls-residence-time-14#ref-I-D.ietf-ospf-ospfv3-lsa-extend>].  Exact use of OSPFv3 LSA
>>    extensions is for further study.
>>
>> NEW TEXT:
>>
>>    The capability to support RTM on a particular link (interface) can be
>>    advertised in OSPFv3 using LSA extensions as described in
>>    [I-D.ietf-ospf-ospfv3-lsa-extend].  The sub-TLV SHOULD use the same
>>    format as in Section 4.3.  The type allocation and full details of
>>    exact use of OSPFv3 LSA extensions is for further study.
>>
>>
>>
>>> Thanks.
>>>
>>> Regards,
>>> Alia
>>>
>>
>>
>