Re: [Lsr] WG Adoption Call for draft-li-lsr-ospfv3-srv6-extensions

["Dongjie (Jimmy)" <[e-mail]>]

Hi Peter,

Please see some comments inline:

> -----Original Message-----
> From: Lsr [mailto:[e-mail]] On Behalf Of Peter Psenak
> Sent: Friday, January 31, 2020 1:24 AM
> To: Acee Lindem (acee) <[e-mail]>; Ketan Talaulikar (ketant)
> <[e-mail]>; [e-mail]; Christian Hopps
> <[e-mail]>; lsr <[e-mail]>
> Cc: lsr-ads <[e-mail]>; draft-li-lsr-ospfv3-srv6-extensions
> <[e-mail]>
> Subject: Re: [Lsr] WG Adoption Call for draft-li-lsr-ospfv3-srv6-extensions
> 
> Hi Acee,
>  
> On 30/01/2020 18:12, Acee Lindem (acee) wrote:
> > Hi Peter,
> >
> > On 1/30/20, 11:36 AM, "Peter Psenak" <[e-mail]> wrote:
> >
> >      Hi Acee,
> >
> >      On 30/01/2020 17:11, Acee Lindem (acee) wrote:
> >      > Hi Ketan,
> >      >
> >      > In that case, it doesn’t make sense to include it in the End.X
> >      > advertisement since you need to look it up to check it anyway. I
> don’t
> >      > see any benefit here.
> >      The benefit is to make sure that the END.X SID that was configured for
> >      the algo X is covered by the locator that has the same algo.
> >
> >      If you do not advertise the algo with END.X SID, you have no way of
> >      checking that on rcv side.
> >
> > Ok - so it is to verify that algorithm for the adjacency matches that algorithm
> for the longest match locator - which may be advertised by a >different
> OSPFv3 router. Correct?
> 
> yes.

In what scenarios will the longest match locator of the END.X SID be advertised by a different router? Does this only happen due to bug or misconfiguration? 

> 
> 
> >I guess I don't see why the algorithm for the END.X SID just isn't defined as
> the algorithm from the longest match locator. That way, everyone in >the area
> would use the same one and there would be less that could go wrong. What
> am I missing?
> 
> locators may change over time. During the reconfiguration a END.X SID may
> wrongly be associated with the incorrect locator from a different algo.

In this case just checking the algorithm may not be enough, if the algorithm happens to be the same, will the END.X SID be considered valid and be used by transit nodes to route towards the originator of the incorrect locator? Some mechanism needs to be considered to avoid using invalid END.X SIDs in such case.

Best regards,
Jie

> Also if for some reason the right locator is not advertised (due to a bug on the
> originator), END.X SID traffic may be sent using a wrong algo. We wanted to
> avoid it as that can be seen as a security issue.
> 
> thanks,
> Peter
> 
> 
> 
> >
> > Thanks,
> > Acee
> >
> >
> >      thanks,
> >      Peter
> >
> >      >
> >      > Thanks,
> >      >
> >      > Acee
> >      >
> >      > *From: *"Ketan Talaulikar (ketant)" <[e-mail]>
> >      > *Date: *Thursday, January 30, 2020 at 11:06 AM
> >      > *To: *Acee Lindem <[e-mail]>, "[e-mail]"
> >      > <[e-mail]>, Christian Hopps
> <[e-mail]>, lsr
> >      > <[e-mail]>
> >      > *Cc: *draft-li-lsr-ospfv3-srv6-extensions
> >      > <[e-mail]>, lsr-ads
> <[e-mail]>
> >      > *Subject: *RE: [Lsr] WG Adoption Call for
> >      > draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      > Hi Acee/Zhen,
> >      >
> >      > The sec 8 of the draft has the following text which specifies the
> >      > handling of this condition.
> >      >
> >      >     All End.X SIDs MUST be subsumed by the subnet of a Locator
> with the
> >      >
> >      >     matching algorithm which is advertised by the same node in an
> SRv6
> >      >
> >      >     Locator TLV.  End.X SIDs which do not meet this requirement
> MUST be
> >      >
> >      >     ignored.
> >      >
> >      > Thanks,
> >      >
> >      > Ketan
> >      >
> >      > *From:* Acee Lindem (acee) <[e-mail]>
> >      > *Sent:* 30 January 2020 21:01
> >      > *To:* [e-mail]; Ketan Talaulikar (ketant)
> >      > <[e-mail]>; Christian Hopps <[e-mail]>; lsr
> <[e-mail]>
> >      > *Cc:* draft-li-lsr-ospfv3-srv6-extensions
> >      > <[e-mail]>; lsr-ads
> <[e-mail]>
> >      > *Subject:* Re: [Lsr] WG Adoption Call for
> >      > draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      > Hi Ketan, Zhen,
> >      >
> >      > What happens if there an algorithm conflict between the Adjacency
> END.X
> >      > SID and the longest match Locator SID? Either one has to take
> precedence
> >      > or this is an error condition. In either case, it needs to be
> documented.
> >      >
> >      > Thanks,
> >      >
> >      > Acee
> >      >
> >      > *From: *"[e-mail]
> <mailto:[e-mail]>"
> >      > <[e-mail] <mailto:[e-mail]>>
> >      > *Date: *Thursday, January 30, 2020 at 10:20 AM
> >      > *To: *"Ketan Talaulikar (ketant)" <[e-mail]
> >      > <mailto:[e-mail]>>, Christian Hopps <[e-mail]
> >      > <mailto:[e-mail]>>, lsr <[e-mail]
> <mailto:[e-mail]>>
> >      > *Cc: *draft-li-lsr-ospfv3-srv6-extensions
> >      > <[e-mail]
> >      > <mailto:[e-mail]>>, lsr-ads
> >      > <[e-mail] <mailto:[e-mail]>>, Christian Hopps
> >      > <[e-mail] <mailto:[e-mail]>>, Acee Lindem
> >      > <[e-mail] <mailto:[e-mail]>>
> >      > *Subject: *Re: RE: [Lsr] WG Adoption Call for
> >      > draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      > For the third concern, I think it is better to list the considerations
> >      > behind the format design of the TLVs to help readers understand
> them
> >      > better. For the specification behavior you mention, this doc SHOULD
> >      > specify it explicitly.
> >      >
> >      > By the way, what a router should do when it receives END.X SID
> >      > containing algorithm that is different from the one carried in the
> >      > convering locator?
> >      >
> >      > Best Regards,
> >      >
> >      > Zhenqiang Li
> >      >
> >      > ------------------------------------------------------------------------
> >      >
> >      > [e-mail] <mailto:[e-mail]>
> >      >
> >      >     *From:*Ketan Talaulikar (ketant) <mailto:[e-mail]>
> >      >
> >      >     *Date:* 2020-01-30 16:44
> >      >
> >      >     *To:*[e-mail]
> <mailto:[e-mail]>;
> >      >     Christian Hopps <mailto:[e-mail]>; lsr
> <mailto:[e-mail]>
> >      >
> >      >     *CC:*draft-li-lsr-ospfv3-srv6-extensions
> >      >     <mailto:[e-mail]>; lsr-ads
> >      >     <mailto:[e-mail]>; Christian Hopps
> >      >     <mailto:[e-mail]>; Acee Lindem (acee)
> <mailto:[e-mail]>
> >      >
> >      >     *Subject:* RE: RE: [Lsr] WG Adoption Call for
> >      >     draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      >     Please check inline again.
> >      >
> >      >     *From:* [e-mail]
> <mailto:[e-mail]>
> >      >     <[e-mail]
> <mailto:[e-mail]>>
> >      >     *Sent:* 30 January 2020 13:46
> >      >     *To:* Ketan Talaulikar (ketant) <[e-mail]
> >      >     <mailto:[e-mail]>>; Christian Hopps
> <[e-mail]
> >      >     <mailto:[e-mail]>>; lsr <[e-mail]
> <mailto:[e-mail]>>
> >      >     *Cc:* draft-li-lsr-ospfv3-srv6-extensions
> >      >     <[e-mail]
> >      >     <mailto:[e-mail]>>; lsr-ads
> >      >     <[e-mail] <mailto:[e-mail]>>; Christian Hopps
> >      >     <[e-mail] <mailto:[e-mail]>>; Acee
> Lindem (acee)
> >      >     <[e-mail] <mailto:[e-mail]>>
> >      >     *Subject:* Re: RE: [Lsr] WG Adoption Call for
> >      >     draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      >     Thank you KT for your quick response. Please see my reply
> begins
> >      >     with [ZQ].
> >      >
> >      >     Best Regards,
> >      >
> >      >     Zhenqiang Li
> >      >
> >      >     ------------------------------------------------------------------------
> >      >
> >      >     [e-mail]
> <mailto:[e-mail]>
> >      >
> >      >         *From:*Ketan Talaulikar (ketant)
> <mailto:[e-mail]>
> >      >
> >      >         *Date:* 2020-01-30 13:42
> >      >
> >      >         *To:*[e-mail]
> <mailto:[e-mail]>;
> >      >         Christian Hopps <mailto:[e-mail]>; lsr
> >      >         <mailto:[e-mail]>
> >      >
> >      >         *CC:*draft-li-lsr-ospfv3-srv6-extensions
> >      >         <mailto:[e-mail]>;
> lsr-ads
> >      >         <mailto:[e-mail]>; Christian Hopps
> >      >         <mailto:[e-mail]>; Acee Lindem (acee)
> >      >         <mailto:[e-mail]>
> >      >
> >      >         *Subject:* RE: [Lsr] WG Adoption Call for
> >      >         draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      >         Hello Zhenqiang Li,
> >      >
> >      >         Thanks for your review and comments. Please check inline
> below.
> >      >
> >      >         *From:*[e-mail]
> >      >         <mailto:[e-mail]>
> <[e-mail]
> >      >         <mailto:[e-mail]>>
> >      >         *Sent:* 30 January 2020 08:46
> >      >         *To:* Christian Hopps <[e-mail]
> >      >         <mailto:[e-mail]>>; lsr <[e-mail]
> >      >         <mailto:[e-mail]>>
> >      >         *Cc:* draft-li-lsr-ospfv3-srv6-extensions
> >      >         <[e-mail]
> >      >         <mailto:[e-mail]>>;
> lsr-ads
> >      >         <[e-mail] <mailto:[e-mail]>>; Christian
> Hopps
> >      >         <[e-mail] <mailto:[e-mail]>>;
> Acee Lindem
> >      >         (acee) <[e-mail] <mailto:[e-mail]>>
> >      >         *Subject:* Re: [Lsr] WG Adoption Call for
> >      >         draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      >         support the adoption with the following comments.
> >      >
> >      >         1. What does SRH stack mean in section 4.2? AS specified
> in
> >      >         RFC8200 and draft-ietf-6man-segment-routing-header,
> only one SRH
> >      >         can be presented in one IPv6 header.
> >      >
> >      >         */[KT] Thanks for catching this error and will fix as
> below:/*
> >      >
> >      >         *//*
> >      >
> >      >         */OLD: /*The Maximum End Pop MSD Type specifies the
> maximum number of SIDs in
> >      >
> >      >             the top SRH in an SRH stack to which the router can
> apply
> >      >         Penultimate
> >      >
> >      >             Segment Pop (PSP) or Ultimate Segment Pop (USP)
> >      >
> >      >         *//*
> >      >
> >      >         */NEW:/*The Maximum End Pop MSD Type specifies the
> maximum number of SIDs in
> >      >
> >      >             the SRH for which the router can apply Penultimate
> >      >
> >      >             Segment Pop (PSP) or Ultimate Segment Pop (USP)
> >      >
> >      >
> >      >
> >      >
> >      >         [ZQ] Fine.
> >      >
> >      >         2. The abbreviations used in this draft should be listed in a
> >      >         seperated section or point out where they are defined.
> >      >
> >      >         */[KT] We’ve followed the convention of expanding on
> first use
> >      >         as also providing reference where necessary. Please do let
> know
> >      >         if we’ve missed doing so anywhere./*
> >      >
> >      >         [ZQ] Some examples: SPF computation in secction 5,  TBD
> in
> >      >         section 2.
> >      >
> >      >         */[KT] Will expand SPF and some other such on first use :-).
> The
> >      >         TBD (to be decided) is for use until the code point are
> >      >         allocated by IANA./*
> >      >
> >      >         3. Algorithm field is defined for End.x SID to carry the
> >      >         algorithm the end.x sid associates. But no algorithm field is
> >      >         defined for End SID in section 7. May I know the reason?
> >      >
> >      >         */[KT] The SRv6 Locator TLV that is the parent of the SRv6
> End
> >      >         SID Sub-TLV carries the algorithm and hence there is no
> need to
> >      >         repeat in the Sub-TLV. This is not the case for SRv6 End.X
> SID
> >      >         Sub-TLV and hence it has the algorithm field./*
> >      >
> >      >         */
> >      >
> >      >
> >      >         /*
> >      >
> >      >         [ZQ] Make sense but still a little bit weird. Since any SID
> >      >         belongs to a locator, or it is not routable, the algorithm
> field
> >      >         in the end.x sid is not needed, end.x sid associates the
> >      >         algorithm carried in the corresponding locator tlv.
> >      >
> >      >         */[KT] Having an algorithm field advertised with the End.X
> SID
> >      >         makes it easier for implementation to find the algorithm
> >      >         specific End.X SID without making the longest prefix match
> on
> >      >         all locators advertised by the node to find the algorithm to
> >      >         which the SID belongs. It also makes it possible to verify
> that
> >      >         the algorithm associated with the End.X SID matches that
> of the
> >      >         covering Locator when the link advertisement with End.X
> SID is
> >      >         received. /*
> >      >
> >      >         *//*
> >      >
> >      >         */Thanks,/*
> >      >
> >      >         */Ketan/*
> >      >
> >      >         *//*
> >      >
> >      >         */Thanks,/*
> >      >
> >      >         */Ketan/*
> >      >
> >      >         Best Regards,
> >      >
> >      >         Zhenqiang Li
> >      >
> >      >         ------------------------------------------------------------------------
> >      >
> >      >         [e-mail]
> <mailto:[e-mail]>
> >      >
> >      >             *From:*Christian Hopps
> <mailto:[e-mail]>
> >      >
> >      >             *Date:* 2020-01-24 04:24
> >      >
> >      >             *To:*lsr <mailto:[e-mail]>
> >      >
> >      >             *CC:*draft-li-lsr-ospfv3-srv6-extensions
> >      >             <mailto:[e-mail]>;
> >      >             lsr-ads <mailto:[e-mail]>; Christian Hopps
> >      >             <mailto:[e-mail]>; Acee Lindem \(acee\)
> >      >             <mailto:[e-mail]>
> >      >
> >      >             *Subject:* [Lsr] WG Adoption Call for
> >      >             draft-li-lsr-ospfv3-srv6-extensions
> >      >
> >      >             Hi LSR WG and Draft Authors,
> >      >
> >      >             The authors originally requested adoption back @
> 105;
> >      >             however, some comments were received and new
> version was
> >      >             produced. Moving forward...
> >      >
> >      >             This begins a 2 week WG adoption poll for the
> following draft:
> >      >
> >      >
> https://datatracker.ietf.org/doc/draft-li-lsr-ospfv3-srv6-extensions/
> >      >
> >      >             Please indicate your support or objection by Feb 6,
> 2020.
> >      >
> >      >             Authors, please respond indicating whether you are
> aware of
> >      >             any IPR that applies to this draft.
> >      >
> >      >             Thanks,
> >      >
> >      >             Chris & Acee.
> >      >
> >      >
> _______________________________________________
> >      >
> >      >             Lsr mailing list
> >      >
> >      >             [e-mail] <mailto:[e-mail]>
> >      >
> >      >             https://www.ietf.org/mailman/listinfo/lsr
> >      >
> >
> >
> >
> >
> >
> 
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