Peter,
> as a matter of fact, SRMS is a SID provisioning tool, whether you
like it or not.
It's not about your or my linking - I was talking about what's the defined
scope so far (architecture doc or protocol docs)
and how you want to extend the scope.
Well, if you want to extend the current scope of SRMS as a "">2)As a global
provisioning tool" -
Plz. do so but not while providing conflict resolution solution.
> It provides all the functionality that is required for such
provisioning tool.
>You can not restrict its usage to SR/LDP interop case.
I didn't restrict anything - Plz. see SRMS stuff so far:
1. https://tools.ietf.org/html/draft-ietf-spring-segment-routing-08#section-3.6
" 3.6.1. Mapping Server
A Remote-Binding SID S advertised by the mapping server M for remote
prefix R attached to non-SR-capable node N signals the same
information as if N had advertised S as a Prefix-SID. Further
details are described in the SR/LDP interworking procedures
([I-D.ietf-spring-segment-routing-ldp-interop]."
2. ISIS:
https://tools.ietf.org/html/draft-ietf-isis-segment-routing-extensions-06#section-2.4
" This functionality is called the
'Mapping Server' and it's used when, in a heterogeneous
network,
not all nodes are capable of advertising their
own SIDs/Labels."
3. OSPF:
https://tools.ietf.org/html/draft-ietf-ospf-segment-routing-extensions-08#section-4
" In some cases it is useful to advertise attributes for a
range of
prefixes. The Segment Routing Mapping Server, which is
described in
[I-D.filsfils-spring-segment-routing-ldp-interop<https://tools.ietf.org/html/draft-ietf-ospf-segment-routing-extensions-08>],
is an example
where we need a single advertisement to advertise SIDs for
multiple
prefixes from a contiguous address range."
Again, plz. extend the scope first and consider the same in resolution
solution. I am fine with it.
--
Uma C.
-----Original Message-----
From: Peter Psenak [mailto:[email protected]]
Sent: Thursday, May 12, 2016 11:03 AM
To: Uma Chunduri; Stefano Previdi (sprevidi)
Cc: Les Ginsberg (ginsberg); [email protected]; [email protected]
Subject: Re: [spring] draft-ginsberg-spring-conflict-resolution - WG adoption
call
Hi Uma,
On 5/12/16 19:49 , Uma Chunduri wrote:
> Stefano,
>
> Thanks for your response.
>
> > using a SRMS for advertising SID on behalf of SR capable nodes does
> not introduce any change in the SR architecture so not
> > sure what we need to document here.
>
> My point below: We are creating a conflict resolution solution for a
> non-existing requirement of using SRMS viz., ">2)As a global provisioning
> tool".
> From your statement above, it seems you have less interest to make this as a
> requirement/scope of SRMS; I am more aligned in that path....
as a matter of fact, SRMS is a SID provisioning tool, whether you like it or
not. It provides all the functionality that is required for such provisioning
tool. You can not restrict its usage to SR/LDP interop case.
thanks,
Peter
>
> On the second point:
>
> > the architecture draft is data-pane agnostic so I presume you refer
> to draft-ietf-spring-segment-routing-mpls.
>
> AFAIS, https://tools.ietf.org/html/draft-ietf-spring-segment-routing-08
> talks about both data planes right from abstract to multiple places (which it
> ought to).
> I leave this to you/WG on where you want to document this -but IMO
> conflict resolution "solution document" in the current form potentially
> introducing fundamental requirements to the system like cross protocol
> verification (with in/across AS). Perhaps some discussion should be there in
> data plane document then.
>
> --
> Uma C.
>
>
> -----Original Message-----
> From: Stefano Previdi (sprevidi) [mailto:[email protected]]
> Sent: Wednesday, May 11, 2016 4:46 AM
> To: Uma Chunduri
> Cc: Les Ginsberg (ginsberg);
> [email protected]<mailto:[email protected]>;
> [email protected]<mailto:[email protected]>
> Subject: Re: [spring] draft-ginsberg-spring-conflict-resolution - WG
> adoption call
>
>
>> On May 6, 2016, at 10:16 PM, Uma Chunduri
>> <[email protected]<mailto:[email protected]>> wrote:
>>
>> Les,
>>
>> 2 quick things.
>>
>> 1.
>> >[Les:] There are two legitimate use cases for SRMS:
>> >1)To advertise SIDs for non-SR
>> capable nodes
>> >2)As a global provisioning tool
>> I am hearing #2 for the first time. I don’t see
>> this either discussed earlier in the WG list or captured in architecture
>> document
>>
>> https://tools.ietf.org/html/draft-ietf-spring-segment-routing-07. Even in
>> the protocol extensions document for example
>>
>> https://tools.ietf.org/html/draft-ietf-isis-segment-routing-extensions-06#section-2.4
>> we always discussed this from non-SR
>> capable nodes PoV. So I request to add this in
>> architecture document before factoring this for solution in conflict
>> resolution.
>
>
> using a SRMS for advertising SID on behalf of SR capable nodes does not
> introduce any change in the SR architecture so not sure what we need to
> document here.
>
>
>
>>
>> 2. Also this is the first time ever we have a requirement for cross
>> protocols verification we ought to discuss the implications of this
>> and protocols involved (with in AS or otherwise) in the architecture
>> document (at least briefly).
>
>
> the architecture draft is data-pane agnostic so I presume you refer to
> draft-ietf-spring-segment-routing-mpls.
>
> with the ipv6 data-plane SR conflicts are in fact solved by ipv6
> addressing techniques ;-)
>
> s.
>
>
>>
>> --
>> Uma C.
>>
>> From: spring [mailto:[email protected]] On Behalf Of Les
>> Ginsberg (ginsberg)
>> Sent: Wednesday, May 04, 2016 9:38 AM
>> To: Uma Chunduri;
>> [email protected]<mailto:[email protected]>;
>> [email protected]<mailto:[email protected]>
>> Subject: Re: [spring] draft-ginsberg-spring-conflict-resolution - WG
>> adoption call
>>
>> Uma –
>>
>> To restate, the problem being addressed here is to guarantee consistent use
>> of SIDs in the forwarding plane network-wide in the presence of conflicting
>> advertisements. The set of advertisements includes both SIDs advertised in
>> protocol prefix reachability advertisements and SRMS advertisements because
>> problems occur based upon inconsistencies in what is installed in the
>> forwarding plane of different routers. It matters not whether Router A used
>> a SID advertised by a protocol prefix reachability advertisement or by an
>> SRMS advertisement – what matter is whether the SID used is consistent with
>> what the neighbors of Router A use. So simply ensuring that OSPF (for
>> example) resolves SIDs in a consistent way does not fully address the
>> problem space.
>>
>> More inline.
>>
>> From: Uma Chunduri [mailto:[email protected]]
>> Sent: Tuesday, May 03, 2016 3:59 PM
>> To: Les Ginsberg (ginsberg);
>> [email protected]<mailto:[email protected]>;
>> [email protected]<mailto:[email protected]>
>> Subject: RE: [spring] draft-ginsberg-spring-conflict-resolution - WG
>> adoption call
>>
>> Les,
>>
>> With all due respects, cross protocol verification of prefix and SID
>> conflicts as an “architectural change” and it can severely impact the
>> existing implementations (at least the one I work on).
>>
>> [Les:] It is quite correct – and I can confirm based on personal experience
>> – that support for conflict resolution is a significant effort.
>>
>> Also I have couple of cases where current version of the draft is not clear
>> about resolution.
>>
>> IMO, first we need clarity with in a protocol instance resolution rules
>> before going to resolve the same across protocols (I mentioned few cases
>> below) .
>> Separation of reachability advertisements and SRMS would help “cross
>> protocol” verification of the ranges and SRMS is not applicable to all
>> protocols.
>>
>>
>> In-line [Uma]:
>>
>> --
>> Uma C.
>>
>> From: Les Ginsberg (ginsberg) [mailto:[email protected]]
>> Sent: Saturday, April 30, 2016 10:11 PM
>> To: Uma Chunduri;
>> [email protected]<mailto:[email protected]>;
>> [email protected]<mailto:[email protected]>
>> Subject: RE: [spring] draft-ginsberg-spring-conflict-resolution - WG
>> adoption call
>>
>> Uma –
>>
>> We are indeed defining conflict resolution across all the SID
>> advertisements regardless of source (protocol or SRMS) –
>>
>> [Uma]: While you can theoretically do anything for current implementation
>> this kind of cross protocol verification is a new architectural requirement.
>> Because it seems “a central entity” need to gather all
>> different protocol instances SRMS advertisements and should settle with
>> resolution.
>>
>> - Also note SRMS is not applicable for BGP but it seems all prefix
>> SIDs need to be verified with IGP instances SRMS advertisements. Is this
>> true? While the document mostly talks about these and compares with prefix
>> advertisement.
>> [Les:] The issue is protocol agnostic.
>>
>> - Algorithm proposed needs more clarity: Take Section 3.2.4
>>
>> o
>> “ 1. Smaller range wins
>>
>> 2. IPv6 entry wins over IPv4 entry
>> …
>> “
>> What happens in case of prefix conflict or SID conflict
>> with only prefix advertisements (range 1). Say multiple prefixes have same
>> SID in one protocol instance and in different protocols.
>> I see 2 levels of resolution required viz., one at within
>> the protocol and one among the protocols. No discussion on this.
>>
>> [Les:] The full set of rules specified in the draft provide deterministic
>> resolution in all cases. You have snipped only the first two rules. If a
>> preference is not obtained based on the first two rules you continue on to
>> rule #3, then rule #4, etc.
>>
>> Similarly in case of SID conflict (range 1), it’s not
>> specified which protocol’s SID need to be considered. Are you assuming some
>> sort of Admin distance play a role in resolution?
>> [Les:] No – admin distance plays no role here.
>>
>> I don’t see any discussion in the document and needs more clarity there
>> too.
>> o Also what happens if a prefix or SID conflict happens with SRMS range 1
>> and a prefix advertisement (2 cases)
>> a. of one protocol and
>> b. multiple protocols?
>>
>> [Les:] The source of the SID advertisement (what protocol/protocol instance
>> or whether it is SRMS based) plays no role. The tie breaker rules as defined
>> are complete and provide a deterministic answer in all cases.
>> If you believe that is not true please provide a specific example where you
>> apply all the rules in the order specified and still do not determine the
>> preferred entry.
>>
>>
>> - On the below assumption: (Section 3.2.4)
>> “This has the nice property that a
>> single misconfiguratoion of an SRMS
>> entry with a large range will not be preferred over a
>> large number of
>> SIDs advertised in prefix reachability advertisements.”
>> While anything can happen in theory, I found it bit odd to see why SRMS
>> entry is being advertised and for the same prefix, SID is also advertised
>> through reachability advertisements?
>> This is against the spirit of SRMS advertisement, isn’t it? While this can
>> happen, it seems we are claiming resolution solution by focusing more on
>> this case in the current version of the document.
>>
>> [Les:] There are two legitimate use cases for SRMS:
>>
>> 1)To advertise SIDs for non-SR capable nodes 2)As a global
>> provisioning tool
>>
>> Let’s examine the first case. I have an LDP enabled network and I begin
>> introducing SR capable nodes. At a given moment in time Router A is NOT SR
>> capable and SRMS advertisements cover prefix SIDs for the addresses
>> associated with Router A.
>> I then upgrade Router A to become SR capable. Because I want to do
>> “make-before-break” I do not immediately remove the SRMS advertisements
>> covering the addresses associated with Router A. I upgrade A, add
>> configuration of SIDs locally on Router A, and verify that the
>> advertisements originating from protocols on Router A are correct. If an
>> inconsistency is introduced when configuring the SIDs on Router A then I
>> will have an SRMS advertisement and a prefix-reachability advertisement that
>> conflict. Until the conflict is corrected we use the conflict resolution
>> rules to provide deterministic forwarding behavior.
>>
>> This to me is a normal and expected upgrade scenario.
>>
>>
>> This is one of the reasons of my first comment below. You got to separate
>> the reachability advertisements and SRMS advertisements; as in principle
>> these are defined for different purposes. I don’t see we need algorithm to
>> prefer reachability advertisement over SRMS advertisement (if we don’t
>> compare these 2 categories).
>>
>>
>>
>> [Les:] I disagree – hopefully my comments have helped you to understand why.
>>
>> Les
>>
>>
>> as the sections you have quoted clearly state.
>>
>> Why? Because we need consistent use of SIDs in the forwarding plane. From
>> forwarding perspective it matters not whether the SID was advertised by
>> protocol instance #1 or #2 or by an SRMS.
>>
>> What matters is that the SID I use to determine what label I install in my
>> forwarding plane is the same SID that my neighbors will use. Otherwise
>> forwarding will be broken.
>>
>> Les
>>
>>
>> From: spring [mailto:[email protected]] On Behalf Of Uma
>> Chunduri
>> Sent: Wednesday, April 27, 2016 4:31 PM
>> To: [email protected]<mailto:[email protected]>;
>> [email protected]<mailto:[email protected]>
>> Subject: Re: [spring] draft-ginsberg-spring-conflict-resolution - WG
>> adoption call
>>
>> Dear Authors,
>>
>> Have few comments on the draft:
>>
>> 1.
>> As I indicated during meeting - I am not sure why we have to club
>> verification of SIDs advertised through regular protocol reachability
>> prefixes and the ranges advertised through 'Mapping Server'
>> (SRMS). I didn't see any compelling reason to do this.
>> SIDs advertised through reachability prefixes doesn't have
>> ranges unlike SRMS advertisements.
>> As SRMS advertisements are primarily for nodes which are
>> not SR capable and I feel we should not mix this with nodes which are SR
>> capable.
>>
>> This isolation helps restricting the resolution work primarily for
>> multiple SRMS entries advertised through one node or multiple nodes.
>> SRMS advertisements are indeed little bit unique in that
>> you are advertising "configuration" on behalf of node X from node Y
>> with ranges (both prefix ranges and SID ranges).
>>
>>
>> 2.
>> Regarding the scope of conflict resolution:
>>
>>
>> Section 1
>>
>> " The problem to be addressed is protocol independent i.e.,
>> segment
>> related advertisements may be originated by multiple nodes using
>> different protocols and yet the conflict resolution MUST be the
>> same
>> on all nodes regardless of the protocol used to transport the
>> advertisements."
>>
>> Section 3.2.8
>> " o In cases where multiple routing protocols are in use
>> mapping
>> entries advertised by all routing protocols MUST be included."
>>
>> This sounds like we are seeking to resolve conflicting entries
>> outside and across the protocols?
>> Each IGP has separate mechanism for advertising mapping entry and I
>> this is not clear with the current version of the draft how we can cross
>> verify SID/Prefix conflict across the protocol.
>> Can you clarify this?
>>
>>
>> --
>> Uma C.
>>
>>
>> -----Original Message-----
>> From: spring [mailto:[email protected]] On Behalf Of
>> [email protected]<mailto:[email protected]>
>> Sent: Thursday, April 14, 2016 12:55 AM
>> To: [email protected]<mailto:[email protected]>
>> Subject: Re: [spring] draft-ginsberg-spring-conflict-resolution - WG
>> adoption call
>>
>>> From: [email protected]<mailto:[email protected]> > Sent:
>>> Thursday, April 14, 2016
>>> 9:51 AM
>>>
>>> Dear WG,
>>>
>>> As we discussed at our meeting last week, working group adoption has
>>> been requested for draft-ginsberg-spring-conflict-resolution.
>>> Please reply to the list with your comments, including although not
>>> limited to whether or not you support adoption.
>>
>> We will end the call on April 29, 2016.
>>
>>
>>> Thanks,
>>>
>>> --John and Bruno
>>>
>>>
>>>
>>> __________________________________________________________
>>> __________________________________________________________
>>> _____
>>>
>>> Ce message et ses pieces jointes peuvent contenir des informations
>>> confidentielles ou privilegiees et ne doivent donc pas etre
>>> diffuses, exploites ou copies sans autorisation. Si vous avez recu
>>> ce message par erreur, veuillez le signaler a l'expediteur et le
>>> detruire ainsi que les pieces jointes. Les messages electroniques
>>> etant susceptibles d'alteration, Orange decline toute responsabilite si ce
>>> message a ete altere, deforme ou falsifie. Merci.
>>>
>>> This message and its attachments may contain confidential or
>>> privileged information that may be protected by law; they should not
>>> be distributed, used or copied without authorisation.
>>> If you have received this email in error, please notify the sender
>>> and delete this message and its attachments.
>>> As emails may be altered, Orange is not liable for messages that
>>> have been modified, changed or falsified.
>>> Thank you.
>>>
>>> _______________________________________________
>>> spring mailing list
>>> [email protected]<mailto:[email protected]>
>>> https://www.ietf.org/mailman/listinfo/spring
>>
>> _____________________________________________________________________
>> _ ___________________________________________________
>>
>> Ce message et ses pieces jointes peuvent contenir des informations
>> confidentielles ou privilegiees et ne doivent donc pas etre diffuses,
>> exploites ou copies sans autorisation. Si vous avez recu ce message par
>> erreur, veuillez le signaler a l'expediteur et le detruire ainsi que les
>> pieces jointes. Les messages electroniques etant susceptibles d'alteration,
>> Orange decline toute responsabilite si ce message a ete altere, deforme ou
>> falsifie. Merci.
>>
>> This message and its attachments may contain confidential or privileged
>> information that may be protected by law; they should not be distributed,
>> used or copied without authorisation.
>> If you have received this email in error, please notify the sender and
>> delete this message and its attachments.
>> As emails may be altered, Orange is not liable for messages that have been
>> modified, changed or falsified.
>> Thank you.
>>
>> _______________________________________________
>> spring mailing list
>> [email protected]<mailto:[email protected]>
>> https://www.ietf.org/mailman/listinfo/spring
>>
>> _______________________________________________
>> spring mailing list
>> [email protected]<mailto:[email protected]>
>> https://www.ietf.org/mailman/listinfo/spring
>
> _______________________________________________
> spring mailing list
> [email protected]<mailto:[email protected]>
> https://www.ietf.org/mailman/listinfo/spring
>
_______________________________________________
spring mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/spring
