Hi, Jie.
I think two conversations got a bit crossed here.
I just checked the final version of -04 as submitted and saw that you
had completely reverted the text about the types (as opposed to the
version with the earlier email to which the comments below applied).
The submitted version is pretty much OK because of the rule change, but
I think that my original comments about identifying what type 1 and type
2 actually are is desirable, and it would be useful to say why 32 is the
limit:
OLD (i.e. submitted -04):
Currently, the type value MUST be verified to be
less than 32, and for type values 1 and 2, the prefix length MUST be
32 and 128 respectively.
NEW:
Currently, the type value MUST be verified to be
less than 32 (i.e., able to identify a specific entity where a loopback can
occur, see Section 4.3), and for type values 1 (IPv4 address) and 2 (IPv6
address), the prefix length MUST be 32 and 128 respectively.
Sorry about the confusion.
I am not an expert in this area, but looking at your conversation with
Lou about label subobjects I saw from RFC 3473 that, if present, one or
two label subobjects MUST follow an IP address subobject that identifies
the node/interface. It doesn't seem to indicate that a label subobject
can occur on its own as an entity identifier to which attributes can be
attached. Lou seemed to think there were cases where it could, but I
don't see that being allowed. This may need clarification.
This also may screw up the words about where to put ERO HOP attributes
in the attributes draft. I'll follow that up separately.
/Elwyn
On 26/02/2015 13:07, Elwyn Davies wrote:
> Hi, Jie.
>
> I checked through the updated draft (-04) that you sent out. That all
> looks fine except for a couple of typos:
>
> s3.2, para 2: s/Explicit Route object/Explicit Route Object/
>
> s5, para 2: s/to remains/to remain/, s/also applies/also apply/
>
> With the added IANA consideration that you have been discussing with
> Lou we should be all done.
>
> I'll continue progressing the presence rule comments with the
> attribute-ro authors.
>
> Thanks for the work.
>
> Regards,
> Elwyn
>
> On 26/02/2015 06:15, Dongjie (Jimmy) wrote:
>> Hi Lou,
>>
>> Thanks a lot for your prompt response.
>>
>> I see that label may be used for some technologies, so I will update
>> the draft following your guidance: keep the previous text and update
>> the IANA allocation rules for type value 5-31. Thanks.
>>
>> Best regards,
>> Jie
>>
>>> -----Original Message-----
>>> From: Lou Berger [mailto:[email protected]]
>>> Sent: Thursday, February 26, 2015 11:40 AM
>>> To: Dongjie (Jimmy); Elwyn Davies; General area reviewing team
>>> Cc: [email protected]
>>> Subject: Re: Gen-art LC review of draft-ietf-teas-rsvp-te-li-lb-03
>>>
>>> Jie,
>>> see below.
>>>
>>> On 02/25/2015 10:00 PM, Dongjie (Jimmy) wrote:
>>>> Hi Elwyn,
>>>>
>>>> Thanks for your prompt response. Attached is a new revision which
>>>> reflects
>>> your comments and suggestions, please let me know if this revision
>>> is OK to
>>> progress, thanks.
>>>> Hi Lou,
>>>>
>>>> Thanks for your suggestion.
>>>>
>>>> In this new revision the text about valid ERO subobject types is
>>>> revised a bit, as
>>> I noticed the type value of "label" (3) is also less than 32, while
>>> it may not be
>>> used to identify a loopback target.
>>> Why not? This is a technology specific issue. For example, one
>>> could loop a
>>> specific lambda in certain optical switches by identifying a
>>> specific lambda via a
>>> label.
>>>
>>>> Currently the IANA allocation rules for 5-31 is not changed by this
>>>> revision. If
>>> you think this change is needed, I can update the draft before
>>> submission.
>>> Thanks.
>>> I think the previous text should be used.
>>>
>>> Thanks,
>>> Lou
>>>
>>>> Cheers,
>>>> Jie
>>>>
>>>>> -----Original Message-----
>>>>> From: Elwyn Davies [mailto:[email protected]]
>>>>> Sent: Thursday, February 26, 2015 2:14 AM
>>>>> To: Dongjie (Jimmy); General area reviewing team
>>>>> Cc: [email protected]
>>>>> Subject: Re: Gen-art LC review of draft-ietf-teas-rsvp-te-li-lb-03
>>>>>
>>>>> Hi, Jie.
>>>>>
>>>>> I think we are almost done.
>>>>>
>>>>> There is a proposal for the specific types at the end.
>>>>>
>>>>> Cheers,
>>>>> Elwyn
>>>>>
>>>>>
>>>>>
>>>>> On 25/02/2015 06:10, Dongjie (Jimmy) wrote:
>>>>>> Hi Elwyn,
>>>>>>
>>>>>> Thanks a lot for your response. Please see my replies inline:
>>>>>>
>>>>>> Best regards,
>>>>>> Jie
>>>>>>
>>>>>>>>> s3.2, para 2:
>>>>>>>>> OLD:
>>>>>>>>> The ingress MUST ensure that the desired loopback mode is
>>>>>>>>> strictly identified in the ERO.
>>>>>>>>>
>>>>>>>>> Am I right that "mode" is a typo? Should it be "node" rather
>>>>>>>>> than "mode? I couldn't see anything about "loopback modes" in RFC
>>>>>>>>> 5860 or RFC 6371. After much head scratching I came to the
>>>>>>>>> conclusion that
>>>>> "node"
>>>>>>>>> was the right answer... If not then please explain where modes
>>>>>>>>> are
>>>>> defined.
>>>>>>>> I guess we may not call it a typo. The above sentence was added
>>>>>>>> during the
>>>>>>> WG review, the intention was to strictly identify the entity at
>>>>>>> which the loopback is desired, which can be either a node or an
>>>>>>> interface of a
>>>>> node.
>>>>>>>> If we replace "mode" with "entity", do you think it can be
>>>>>>>> clearer?
>>>>>>>>
>>>>>>>>> Continuing on the basis that the word s/b "node"... I think
>>>>>>>>> this would
>>>>>>>>> be clearer as follows:
>>>>>>>>> NEW
>>>>>>>>> The ingress node MUST ensure that the node where loopback is
>>>>>>>>> intended to occur is marked as a strict hop (i.e., not a loose
>>>>>>>>> hop) in the
>>>>> ERO.
>>>>>>>> If you agree with the above change, in your suggestion we can also
>>>>>>>> substitute
>>>>>>> "node" with "entity".
>>>>>>> That would help. How about:
>>>>>>> NEW (mk 2):
>>>>>>>
>>>>>>> The ingress node MUST ensure that the entity (node or interface),
>>>>>>> at which loopback is intended to occur, is marked as a strict hop
>>>>>>> (i.e., not a loose hop) in the ERO type subobject.
>>>>>> Agree with this description. Will update in the new revision.
>>>>> Fine.
>>>>>>>> The prior subobject of "ERO Hop Attributes subobject" would also
>>>>>>>> be ERO
>>>>>>> subobject which identifies the target entity of loopback. As
>>>>>>> specified in the sentence below, the type value of the prior
>>>>>>> subobject ensures the prior subobject would be an IP prefix or an
>>>>>>> interface ID, which can identify the node or interface at which
>>>>>>> loopback is desired. Note that the current description requires
>>>>>>> both the "ERO Hop Attributes subobject" and the prior subobject
>>>>>>> have the L bit set to 0 to ensure that the two subobjects together
>>>>>>> strictly specify a
>>>>> loopback request on an specific entity (node or interface).
>>>>>>>> We can rephrase to make it clearer.
>>>>>>> I have looked into this issue a bit more deeply, and realize that
>>>>>>> my problem is not really with this draft but, at least partly, with
>>>>>>> draft-ietf-teas-lsp-attribute-ro-01. Having gone back to RFC3209,
>>>>>>> I understand that the subobjects in an ERO as defined there are all
>>>>>>> specifiers for type of 'entity' that could be waypoints on the
>>>>>>> explicit route. There is no allowance for other types of subobject
>>>>>>> (such as the attribute subobjects being introduced by
>>>>>>> draft-ietf-teas-lsp-attribute-ro-01). As introduced in RFC 3209,
>>>>>>> both EROs and RROs contained only entity type subobjects, but RFC
>>>>>>> 5420 changed this for *RROs only* by introducing RRO Attributes
>>>>>>> subobjects which could be inserted between the type subobjects.
>>>>>>> Thus as standardized currently, EROs aren't allowed any other sort
>>>>>>> of subobject
>>>>> and there is no equivalent to the "Presence Rules" defined for RROs
>>>>> in RFC 5420 section 7.3.1.
>>>>>>> draft-ietf-teas-lsp-attribute-ro-01 updates the presence rules for
>>>>>>> RROs to allow for the RRO Hop Attributes subobjects but the
>>>>>>> necessary presence rules that would control where the ERO HOP
>>>>>>> Attributes could be inserted are not properly defined in
>>>>>>> draft-ietf-teas-lsp-attribute-ro-01. Para 1 of s2.3 of
>>>>>>> draft-ietf-teas-lsp-attribute-ro-01 seems to indicate that the HOP
>>>>>>> Attributes would be placed after all the type subobjects which
>>>>>>> doesn't seem right. I would have thought that the hop attributes
>>>>>>> needed to be interleaved between the type subobjects - and I think
>>>>>>> that is what the existing text in the lock draft is trying to say.
>>>>>>>
>>>>>>> So I think the draft-ietf-teas-lsp-attribute-ro-01 needs to be
>>>>>>> clarified
>>>>>>> - a specific section on Presence Rules as in RFC 5420 would help.
>>>>>>>
>>>>>>> The text about checking that the L bit in the lock draft is
>>>>>>> confusing, because the L bit is *required* by
>>>>>>> draft-ietf-teas-lsp-attribute-ro-01
>>>>>>> to be 0 in *all* Hop Attributes subobjects whether they are
>>>>>>> associated with loose or strict hops and need not be mentioned.
>>>>>>> The L bit is only set in the type subobject if it is a loose hop so
>>>>>>> the check should
>>>>> be
>>>>>>> that the type subobject has its L bit clear. It should also
>>>>>>> be made
>>>>>>> clearer in the lock draft that there can be multiple Hop Attribute
>>>>>>> subobjects after the type subobject.
>>>>>>>
>>>>>>> I hope this helps.
>>>>>> You are correct, the L bit in the ERO hop attributes subobject must
>>>>>> be 0, thus
>>>>> we would only specify that the L bit in the prior ERO subobject MUST
>>>>> be set to 0 in the new revision.
>>>>> OK.
>>>>>> As for the rules about multiple Hop Attribute subobjects in ERO, IMO
>>>>>> maybe it
>>>>> is more suitable to be specified in draft-ietf-teas-lsp-attribute-ro,
>>>>> but we can also add such descriptions if you think they belongs to
>>>>> this draft.
>>>>> I will negotiate with the authors of draft-ietf-teas-lsp-attribute-ro
>>>>> to see if we can agree a revision.
>>>>>>>>> s3.2, para 3:
>>>>>>>>>> Currently, the type value MUST be verified to be
>>>>>>>>>> less than 32, and for type values 1 and 2 the prefix
>>>>>>>>>> length MUST
>>> be
>>>>>>>>>> 32 and 128 respectively.
>>>>>>>>> It would be better to use the names of the types (1 = IPv4, 2 =
>>>>>>>>> IPv6) that would make it clearer why the lengths are as they are
>>> specified.
>>>>>>>>> Is it possible to explain why the type has to be less than this
>>>>>>>>> apparently arbitrary limit of 32? And hence what allocation
>>>>>>>>> constraints ought to be applied in the future - this might need a
>>>>>>>>> change in the IANA allocation rules that should be specified in
>>>>>>>>> this
>>>>> document.
>>>>>>>> The limit of 32 was to ensure the subobject type can identify a
>>>>>>>> specific node
>>>>>>> or interface. Maybe we can specify the required types (node,
>>>>>>> interface) explicitly to make it clear.
>>>>>>> That would help.
>>>>>>> It has just occurred to me why you want to say that the prefix
>>>>>>> lengths are
>>>>>>> 32/128 bits - so that the IP address refers to exactly one node.
>>>>>>> However this is possibly confusing because RFC 3209 *requires* the
>>>>>>> values to be 32/128 respectively and the subobjects do carry just a
>>>>>>> host address and not a domain prefix as might be implied by
>>>>>>> lower values.
>>>>>> As specified in 4.3.3 of RFC 3209, for the ERO subobjects, the
>>>>>> prefix lengths
>>>>> are not required to be just 32/128. While as specified in 4.4.1 of
>>>>> RFC 3209, for the RRO subobjects, the prefix lengths are required
>>>>> to be
>>> 32/128.
>>>>> You are right: I missed that RRO and ERO were different. So
>>>>> specifying the prefix lengths is indeed needed as you say.
>>>>>>> I noted having looked again at the registry [1], and it appears
>>>>>>> that nobody has yet defined an ERO type for 4 octet AS numbers
>>>>>>> which have now
>>>>>>> (finally) been standardized. This might mean that 32 was not the
>>>>>>> right boundary. Perhaps this means that you need to define an
>>>>>>> update to the allocation rules for the registry so that values
>>>>>>> below (say)
>>>>>>> 32 are required to identify exactly one physical node and not an
>>>>>>> abstract node with potentially many physical nodes.
>>>>>> Thanks for your suggestion. Since this draft just want to restrict
>>>>>> the type of
>>>>> ERO subobjects that can appear prior to the ERO hop attributes
>>>>> subobject, making such update to IANA was not our original intention,
>>>>> also requires discussion with ADs and TEAS chairs.
>>>>>> What about we specify the allowed ERO subobject types explicitly,
>>>>>> similar to
>>>>> 6.1.1 of RFC 4990? The specification could be something like:
>>>>>> The prior subobject MUST be able to identify a specific node or
>>>>>> interface,
>>>>> specifically it MUST be one of the following: type "IPv4 prefix" with
>>>>> prefix length 32, type "IPv6 prefix" with prefix length 128, or type
>>>>> "Unnumbered Interface ID".
>>>>> That would certainly cover the situation as it is at the moment. I
>>>>> can't immediately think of any new types that might be added and
>>>>> would be relevant as loopback points, but you might have some
>>>>> ideas on
>>> this.
>>>>> I was trying to think of an easy way to factor this into the IANA
>>>>> registration process but I can't see anything very simple. I think a
>>>>> few 'weasel words' will do for an unlikely event. How about:
>>>>> NEW mk 3:
>>>>> The prior subobject MUST be able to identify a specific node or
>>>>> interface, specifically, at the time of writing, it can be one of the
>>>>> following:
>>>>> - Type "IPv4 prefix" with prefix length 32,
>>>>> - Type "IPv6 prefix" with prefix length 128, or
>>>>> - Type "Unnumbered Interface ID".
>>>>> If any new subobject types are defined in future and they identify a
>>>>> specific node or interface, the specification of the new type can
>>>>> extend this
>>> list.
>>>>>
>>>>>>> [1]
>>>>>>> http://www.iana.org/assignments/rsvp-parameters/rsvp-parameters.xml
>>>>>>> #r
>>>>>>> svp-
>>>>>>> parameters-25
>
