Hi Ketan
From: Ketan Talaulikar (ketant) [mailto:[email protected]]
Sent: Thursday, October 17, 2019 7:49 PM
To: DECRAENE Bruno TGI/OLN
Cc: idr wg; SPRING WG List
Subject: RE: draft-ietf-spring-segment-routing-policy
Hi Bruno,
I now understand your point with the two draft references you have provided. I
do believe we need to ensure that the “Types” in [1] are managed in a way that
future values are kept consistent across drafts/areas.
It might be too late for the codepoints in
draft-ietf-idr-segment-routing-te-policy since we have implementations and
deployments, but we can ensure for everything else.
Would you suggest we get create a registry with IANA for this via
draft-ietf-spring-segment-routing-policy? Or is there some other way?
[Bruno] I’m not aware of other ways. I was suggesting to create an IANA
registry, but your comment that this is restricted for protocol code points
make me doubt.
There is also the option of removing the Type numbers if you
think that they are not that useful. That would remove the problem. Possibly
with using shorter names for them (e.g, MPLS label, IPv6 SID, …)
At this point, the subject looks restricted to SPRING, so possibly we could
stop copying IDR.
Thanks,
--Bruno
Thanks,
Ketan
From: [email protected] <[email protected]>
Sent: 17 October 2019 20:24
To: Ketan Talaulikar (ketant) <[email protected]>
Cc: idr wg <[email protected]>; SPRING WG List <[email protected]>
Subject: RE: draft-ietf-spring-segment-routing-policy
Hi Ketan,
My point was not related to the alignment of code points but to the fact that
there is no provision taken to guarantee that in the future “Types” defined in
[1] be unique/(a unique idenfitier).
This type may eventually be used in protocol, e.g. yang model [2], in which
case collision would be an issue.
But if a collision of such SID types, as defined in [1], is acceptable for you,
let it be. In which case, possibly [2] should use the names rather than the
number (e.g. “SR-MPLS Label” rather than “segment-type-1”)
[1]
https://tools.ietf.org/html/draft-ietf-spring-segment-routing-policy-03#section-4
[2]
https://tools.ietf.org/html/draft-raza-spring-sr-policy-yang-01#section-4.2.1
--Bruno
From: Ketan Talaulikar (ketant) [mailto:[email protected]]
Sent: Thursday, October 17, 2019 8:27 AM
To: DECRAENE Bruno TGI/OLN
Cc: idr wg; SPRING WG List
Subject: RE: draft-ietf-spring-segment-routing-policy
Hi Bruno,
A codepoint is a number that is allocated by IANA and sent over the wire as
part of a protocol encoding. It is protocol/registry specific. E.g. we can have
the same Segment Type signalled by codepoint “9” in
https://tools.ietf.org/html/draft-ietf-idr-te-lsp-distribution-12#section-9.7
while it is signalled by codepoint “10” in
https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-07#section-8.4
– there is no issue functionally. It would be nice to have those aligned
across the two since they have semantic similarity but it is not necessary.
A reference is just that – a short form instead of using a long descriptive
name. So a segment of “Type 9” that is referred in
https://tools.ietf.org/html/draft-ietf-spring-segment-routing-policy-03#section-4
is what is signalled using codepoint 9 in BGP-LS while using codepoint 10 for
SRTE. You will see places in the draft-ietf-spring-segment-routing-policy where
these “types” are referred to – e.g.
https://tools.ietf.org/html/draft-ietf-spring-segment-routing-policy-03#section-5.1.
Ideally, it would have been great to have the reference and codepoints (across
registries) aligned – but it is not necessary.
In summary, besides the correction needed in
draft-ietf-idr-segment-routing-te-policy in section 2.4.3.2 (and it’s
sub-sections) as described in my email below, I do not see any issue here.
If you think we need some text changes to improve this clarity in any draft,
please do suggest.
Thanks,
Ketan
From: [email protected]<mailto:[email protected]>
<[email protected]<mailto:[email protected]>>
Sent: 15 October 2019 14:46
To: Ketan Talaulikar (ketant) <[email protected]<mailto:[email protected]>>
Cc: idr wg <[email protected]<mailto:[email protected]>>; SPRING WG List
<[email protected]<mailto:[email protected]>>
Subject: RE: draft-ietf-spring-segment-routing-policy
Hi Keta,
Please check inline [Bruno2]
From: Ketan Talaulikar (ketant) [mailto:[email protected]]
Sent: Tuesday, October 15, 2019 6:56 AM
To: DECRAENE Bruno TGI/OLN; SPRING WG List
Cc: idr wg
Subject: RE: draft-ietf-spring-segment-routing-policy
Hi Bruno,
Please check inline below.
From: [email protected]<mailto:[email protected]>
<[email protected]<mailto:[email protected]>>
Sent: 23 September 2019 22:08
To: Ketan Talaulikar (ketant) <[email protected]<mailto:[email protected]>>;
SPRING WG List <[email protected]<mailto:[email protected]>>
Cc: idr wg <[email protected]<mailto:[email protected]>>
Subject: RE: draft-ietf-spring-segment-routing-policy
Hi Ketan,
Thanks for the complete answer. And sorry for my delay in responding.
More inline [Bruno]
From: Ketan Talaulikar (ketant) [mailto:[email protected]]
Sent: Friday, August 2, 2019 4:37 AM
To: DECRAENE Bruno TGI/OLN; SPRING WG List
Cc: idr wg
Subject: RE: draft-ietf-spring-segment-routing-policy
+ IDR WG since some of the affected documents are IDR WG drafts
Hi Bruno,
I agree that the draft-ietf-spring-segment-routing-policy [1] is the right
place to normatively define the different segment types and perhaps would have
been the right document to create an IANA registry for them.
I also agree that the draft-ietf-idr-segment-routing-te-policy [2] has a
discrepancy between its IANA section 8.4 for the Segment-List sub-TLV space and
section 2.4.3.2 (and it’s sub-sections) where the different Segment Types have
been defined. I will request the authors of this draft to fix the text in
section 2.4.3.2 (and it’s sub-sections) for the types 8 and above to adjust for
the codepoint 9 allocated for the weight sub-TLV.
At this point, given the implementations available and already deployed for
[2], I doubt if we can correct and map the segment types in that draft to what
has been defined in [1].
There is also the
https://tools.ietf.org/html/draft-ietf-idr-te-lsp-distribution-11#section-9.7
which creates the Segment Types IANA registry (aligned with [1]).
[Bruno] This IANA registry seems BGP-LS specific. (sub-registry under "Border
Gateway Protocol - Link State (BGP-LS) Parameters")
On a side note,
> “The registry contains the following codepoints (suggested values, to be
> assigned by IANA)”
Since you define a new registry, you can populate initial allocations at your
own will. IOW :s/(suggested values, to be assigned by IANA)”/
[KT] Thanks. Fixed it in the version just posted.
And then I am not sure if draft-raza-spring-sr-policy-yang is able to
benefit/leverage the IANA registry from [1].
So unless we can have the IANA registry created via [1] being consistently used
in all dependent documents, I do not see much gain in setting up the Segment
Type registry under IANA at this point.
[Bruno] Make sense, but brings three clarification questions:
Is there a need for draft-ietf-spring-segment-routing-policy to define numbers
for the segment types (or is the name enough)?
[KT] The names are long and descriptive (as you can see) and hence the numbers
allow for easy reference through the rest of the document.
[Bruno2] I’m fine with a number. But if the numbers are to be used as a useful
reference, it looks like a number must only reference one type of segment.
IOW, if someone reference: Type 2: SRv6 SID: while someone else use the same
number for a different reference: Type 2: SR-MPLS Label. then Type 2 doesn’t
seem like a useful reference anymore.
If yes, do we need such numbers of be unique (avoid collisions)?
[KT] The numbers in draft-ietf-spring-segment-routing-policy are not
code-points today and just reference numbers. So there is no concept of
collision with the code-points defined in other registries? Would it help if
draft-ietf-spring-segment-routing-policy were to refer to segment types as
A,B,C so as to avoid this confusion? 😊
[Bruno2] no, that would not help in any way.
I’m not sure what the difference you make between a code point and a reference.
Is the former to be used by computer and the latter by humans? If so, don’t you
think that human also deserve unambiguous reference?
If yes, how do you propose to avoid code point collisions in the future?
(Or do you assume that there won’t be future ones?)
[KT] I would not rule out future segment types.
[Bruno2] That seem to answer the second question in brackets, but not the main
one.
Let’s take an example: would you be fine with a document defining Type 2: SRv6+
SID: ?
If so, what’s the purpose of a reference (type 2) which does not
uniquely identify something?
If not, how do you propose to avoid collision between reference numbers?
Taking another example, lets reference “coffee” as type 2 and “tea” as type 2.
Could you please bring me a cup of type 2?
Thanks,
--Bruno
Thanks,
Ketan
Thanks,
Bruno
Thanks,
Ketan
From: spring <[email protected]<mailto:[email protected]>> On
Behalf Of [email protected]<mailto:[email protected]>
Sent: 01 August 2019 19:10
To: SPRING WG List <[email protected]<mailto:[email protected]>>
Subject: [spring] draft-ietf-spring-segment-routing-policy
Hi authors,
Speaking as individual contributor.
This document seems to define multiple types of segments (1 to 11).
May be this document would be the right place to define them normatively and
creates the IANA registry for them. And this seems like a work for spring.
Otherwise, there is a risk that other documents redefine them, possibly in a
non-consistent manner. (1) E.g. the BGP draft is not using the same type
numbers/name, which may bring confusion. I would expect YANG models to also
need these types.
BTW is there any chance to align the types in the BGP document or is this too
late? (alternatively may be changing the types in the sr-policy document)
Thanks,
Regards,
Bruno
(1)
SR-policy:
Type 1: SR-MPLS Label:
Type 2: SRv6 SID:
Type 3: IPv4 Prefix with optional SR Algorithm:
Type 4: IPv6 Global Prefix with optional SR Algorithm for SR-MPLS:
Type 5: IPv4 Prefix with Local Interface ID:
Type 6: IPv4 Addresses for link endpoints as Local, Remote pair:
Type 7: IPv6 Prefix and Interface ID for link endpoints as Local, Remote
pair for SR-MPLS:
Type 8: IPv6 Addresses for link endpoints as Local, Remote pair for SR-MPLS:
Type 9: IPv6 Global Prefix with optional SR Algorithm for SRv6:
Type 10: IPv6 Prefix and Interface ID for link endpoints as Local, Remote
pair for SRv6:
Type 11: IPv6 Addresses for link endpoints as Local, Remote pair for SRv6:
BGP:
1 MPLS SID sub-TLV This document
2 SRv6 SID sub-TLV This document
3 IPv4 Node and SID sub-TLV This document
4 IPv6 Node and SID for SR-MPLS sub-TLV This document
5 IPv4 Node, index and SID sub-TLV This document
6 IPv4 Local/Remote addresses and SID sub-TLV This document
7 IPv6 Node, index for remote and local pair This document
and SID for SR-MPLS sub-TLV
8 IPv6 Local/Remote addresses and SID sub-TLV This document
9 Weight sub-TLV This document
10 IPv6 Node and SID for SRv6 sub-TLV This document
11 IPv6 Node, index for remote and local pair This document
and SID for SRv6 sub-TLV
12 IPv6 Local/Remote addresses and SID for This document
SRv6 sub-TLV
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