Re: [Lsr] New Version Notification for draft-wang-lsr-isis-mfi-00.txt

Tony Przygienda <tonysietf@gmail.com> Tue, 09 March 2021 10:48 UTC

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From: Tony Przygienda <tonysietf@gmail.com>
Date: Tue, 9 Mar 2021 11:47:49 +0100
Message-ID: <CA+wi2hO_fBZ-W9B72KEdibkhG8p_2PcigDzmR0MyHMB-PqPYGA@mail.gmail.com>
To: Gyan Mishra <hayabusagsm@gmail.com>
Cc: Peter Psenak <ppsenak@cisco.com>, Robert Raszuk <robert@raszuk.net>, Huzhibo <huzhibo@huawei.com>, Aijun Wang <wangaj3@chinatelecom.cn>, Tony Li <tony.li@tony.li>, lsr <lsr@ietf.org>, Tianran Zhou <zhoutianran@huawei.com>, wangyali <wangyali11@huawei.com>
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Subject: Re: [Lsr] New Version Notification for draft-wang-lsr-isis-mfi-00.txt
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Gyan, you are confusing RIB with LSDB. It is absolutely feasible and normal
to generate multiple RIBs/FIBs from a single LSDB and that has been done
for about forever

problem with lots of those proposals and assertions here is that powerpoint
and rfc text always compiles no matter what you put into it, silicon and
real implementations force to face the world not as you imagine it but as
you can actually make it work in practical terms. Akin to talking about
pottery (*there is a value to it in itself) and making a real pot with
clay. Making a real pot first gives you a much better chance to actually
talk about pottery meaningfully albeit it does not teach you aesthetics of
pottery or a complete new way to make pots possibly.

2c

-- tony

On Fri, Mar 5, 2021 at 5:11 PM Gyan Mishra <hayabusagsm@gmail.com> wrote:

> Hi Peter
>
> On Fri, Mar 5, 2021 at 10:56 AM Peter Psenak <ppsenak@cisco.com> wrote:
>
>> Gyan,
>>
>> On 05/03/2021 16:46, Gyan Mishra wrote:
>> > Yali
>> >
>> > I agree with a Peter.
>> >
>> > As for resource isolation and provisioning of a VTN I think you really
>> > need separate LSDB instances provided by MT or MI as better suited for
>> > network slicing.
>>
>> MT does not provide LSDB separation, only MI does.
>>
>> thanks,
>> Peter
>
>
>    I thought that each MT topology was a separate RIB meaning separate
> LSDB.  The RFC is confusing.😄
>
> https://tools.ietf.org/html/rfc5120
>
> 6 <https://tools.ietf.org/html/rfc5120#section-6>.  MT SPF Computation
>
>    Each MT MUST run its own instance of the decision process.  The
>    pseudo-node LSPs are used by all topologies during computation.  Each
>    non-default topology MAY have its attached bit and overload bit set
>    in the MT TLV.  A reverse-connectivity check within SPF MUST follow
>    the according MT to assure the bi-directional reachability within the
>    same MT.
>
>    The results of each computation SHOULD be stored in a separate
>    Routing Information Base (RIB), in normal cases, otherwise
>    overlapping addresses in different topologies could lead to
>    undesirable routing behavior, such as forwarding loops.  The
>    forwarding logic and configuration need to ensure the same MT is
>    traversed from the source to the destination for packets.  The
>    nexthops derived from the MT SPF MUST belong to the adjacencies
>
>
> conforming to the same MT for correct forwarding.  It is recommended
>    for the administrators to ensure consistent configuration of all
>    routers in the domain to prevent undesirable forwarding behavior.
>
>    No attempt is made in this document to allow one topology to
>    calculate routes using the routing information from another topology
>    inside SPF.  Even though it is possible to redistribute and leak
>    routes from another IS-IS topology or from external sources, the
>    exact mechanism is beyond the scope of this document.
>
>
>
>>
>> >
>> > To me it seems a common LSDB shared among network slices VTN underlay
>> > could be problematic with network overlap issues.
>> >
>> > Kind Regards
>> >
>> > Gyan
>> >
>> > On Fri, Mar 5, 2021 at 10:28 AM Peter Psenak <ppsenak@cisco.com
>> > <mailto:ppsenak@cisco.com>> wrote:
>> >
>> >     Hi Yali,
>> >
>> >     On 05/03/2021 15:31, wangyali wrote:
>> >      > Hi Peter,
>> >      >
>> >      > Thanks for your question. Please see inline [yali3].
>> >      >
>> >      > -----Original Message-----
>> >      > From: Peter Psenak [mailto:ppsenak@cisco.com
>> >     <mailto:ppsenak@cisco.com>]
>> >      > Sent: Thursday, March 4, 2021 11:20 PM
>> >      > To: wangyali <wangyali11@huawei.com
>> >     <mailto:wangyali11@huawei.com>>; Gyan Mishra <hayabusagsm@gmail.com
>> >     <mailto:hayabusagsm@gmail.com>>; Robert Raszuk <robert@raszuk.net
>> >     <mailto:robert@raszuk.net>>
>> >      > Cc: Huzhibo <huzhibo@huawei.com <mailto:huzhibo@huawei.com>>;
>> >     Aijun Wang <wangaj3@chinatelecom.cn
>> >     <mailto:wangaj3@chinatelecom.cn>>; Tony Li <tony.li@tony.li
>> >     <mailto:tony.li@tony.li>>; lsr <lsr@ietf.org <mailto:lsr@ietf.org
>> >>;
>> >     Tianran Zhou <zhoutianran@huawei.com <mailto:zhoutianran@huawei.com
>> >>
>> >      > Subject: Re: [Lsr] New Version Notification for
>> >     draft-wang-lsr-isis-mfi-00.txt
>> >      >
>> >      > Hi Yali,
>> >      >
>> >      > On 04/03/2021 14:45, wangyali wrote:
>> >      >> Hi Peter,
>> >      >>
>> >      >> Please see inline [Yali2]. Thanks a lot.
>> >      >>
>> >      >> -----Original Message-----
>> >      >> From: Peter Psenak [mailto:ppsenak@cisco.com
>> >     <mailto:ppsenak@cisco.com>]
>> >      >> Sent: Thursday, March 4, 2021 6:50 PM
>> >      >> To: wangyali <wangyali11@huawei.com
>> >     <mailto:wangyali11@huawei.com>>; Gyan Mishra
>> >      >> <hayabusagsm@gmail.com <mailto:hayabusagsm@gmail.com>>; Robert
>> >     Raszuk <robert@raszuk.net <mailto:robert@raszuk.net>>
>> >      >> Cc: Huzhibo <huzhibo@huawei.com <mailto:huzhibo@huawei.com>>;
>> >     Aijun Wang
>> >      >> <wangaj3@chinatelecom.cn <mailto:wangaj3@chinatelecom.cn>>;
>> Tony
>> >     Li <tony.li@tony.li <mailto:tony.li@tony.li>>; lsr
>> >      >> <lsr@ietf.org <mailto:lsr@ietf.org>>; Tianran Zhou
>> >     <zhoutianran@huawei.com <mailto:zhoutianran@huawei.com>>
>> >      >> Subject: Re: [Lsr] New Version Notification for
>> >      >> draft-wang-lsr-isis-mfi-00.txt
>> >      >>
>> >      >> Hi Yali,
>> >      >>
>> >      >> On 04/03/2021 11:42, wangyali wrote:
>> >      >>> Hi Peter,
>> >      >>>
>> >      >>> Please review follows tagged by [Yali].
>> >      >>>
>> >      >>>
>> >      >>> -----Original Message-----
>> >      >>> From: Peter Psenak [mailto:ppsenak@cisco.com
>> >     <mailto:ppsenak@cisco.com>]
>> >      >>> Sent: Wednesday, March 3, 2021 5:37 PM
>> >      >>> To: wangyali <wangyali11@huawei.com
>> >     <mailto:wangyali11@huawei.com>>; Gyan Mishra
>> >      >>> <hayabusagsm@gmail.com <mailto:hayabusagsm@gmail.com>>; Robert
>> >     Raszuk <robert@raszuk.net <mailto:robert@raszuk.net>>
>> >      >>> Cc: Huzhibo <huzhibo@huawei.com <mailto:huzhibo@huawei.com>>;
>> >     Aijun Wang
>> >      >>> <wangaj3@chinatelecom.cn <mailto:wangaj3@chinatelecom.cn>>;
>> >     Tony Li <tony.li@tony.li <mailto:tony.li@tony.li>>; lsr
>> >      >>> <lsr@ietf.org <mailto:lsr@ietf.org>>; Tianran Zhou
>> >     <zhoutianran@huawei.com <mailto:zhoutianran@huawei.com>>
>> >      >>> Subject: Re: [Lsr] New Version Notification for
>> >      >>> draft-wang-lsr-isis-mfi-00.txt
>> >      >>>
>> >      >>> Yali,
>> >      >>>
>> >      >>> On 03/03/2021 06:02, wangyali wrote:
>> >      >>>> Hi Peter,
>> >      >>>>
>> >      >>>> Thanks for your comments. Yes. I am improving this sentence.
>> >     Please review the following update.
>> >      >>>>
>> >      >>>> OLD: " And Level 1/Level 2 PSNP and Level 1/Level 2 CSNP
>> >     containing information about LSPs that transmitted in a specific MFI
>> >     are generated to synchronize the LSDB corresponding to the specific
>> >     MFI."
>> >      >>>>
>> >      >>>> NEW: "And Level 1/Level 2 PSNP and Level 1/Level 2 CSNP
>> >     containing information about LSPs that transmitted in a specific MFI
>> >     are generated to synchronize the MFI-specific sub-LSDB. Each
>> >     MFI-specific sub-LSDB is subdivided from a single LSDB."
>> >      >>>
>> >      >>> please specify sub-LSDB.
>> >      >>> [Yali] Thanks for your comment. But to avoid introducing a new
>> >     term, I change to use "MFI-specific LSDB" instead of " MFI-specific
>> >     sub-LSDB ".  And we give the explanation that "Each MFI-specific
>> >     LSDB is subdivided from a single LSDB."
>> >      >>
>> >      >> I wonder what is the difference between "MFI-specific LSDB
>> >     subdivided from a single LSDB" versus the "MFI-specific LSDB".
>> >      >> [Yali2]: Actually I am trying to optimize and accurately
>> >     describe the key point that multiple Update processes associated
>> >     with each MFI operate on a common LSDB within the zero IS-IS
>> >     instance, and each Update process is isolated from each other and
>> >     does not affect each other.
>> >      >> So we say "MFI-specific LSDB subdivided from a single LSDB",
>> >     which may explicitly indicate each MFI-specific LSDB shares a common
>> >     LSDB but each Update process associated with a MFI is isolated.
>> >     However, from your previous question and suggestions,  "MFI-specific
>> >     LSDB" looks like unclear and misleading. Any good idea on improving
>> >     the expression are welcome.
>> >      >
>> >      >
>> >      > it's not the name that is as important. It's the concept that
>> >     looks questionable - how well can you isolate the update processing
>> >     if the data are part of the same LSDB and whether such update
>> >     process separation would prove to be useful at all. I don't know, so
>> >     far I have not seen any evidence.
>> >      > [yali3] This draft defines a new TLV, i.e. MFI-ID TLV,  which may
>> >     be included in each Level 1/Level 2 IS-IS LSPs and SNPs. Hence, each
>> >     Level 1/Level 2 LSPs and SNPs associated with each Update Process
>> >     can be uniquely identified by MFI-ID.
>> >      > In this draft, each flooding instance has its own separated
>> >     Update process, which isolates the impact of application information
>> >     flooding on the IS-IS protocol operation. So each Level 1/Level 2
>> >     LSP associated with a specific MFI carries flooding information
>> >     belonging to the specific MFI. And Level 1/Level 2 PSNP and Level
>> >     1/Level 2 CSNP containing information about LSPs that propagated in
>> >     the specific MFI are generated to synchronize the MFI-specific LSDB.
>> >
>> >     - by using the same LSDB to store the MFI specific information only
>> a
>> >     limited separation can be achieved. Multi-instance gives you better
>> >     separation.
>> >
>> >     - you carved the MFI specific LSP space from the common LSP space.
>> This
>> >     may result in the non routing apps consuming the space that would
>> >     otherwise be required for regular routing information, compromising
>> the
>> >     basic functionality of the protocol. Multi-instance does not have
>> that
>> >     problem.
>> >
>> >     my 2c,
>> >     Peter
>> >
>> >
>> >      >
>> >      > thanks,
>> >      > Peter
>> >      >
>> >      >
>> >      >
>> >      >
>> >      >>
>> >      >> thanks,
>> >      >> Peter
>> >      >>
>> >      >>>
>> >      >>> thanks,
>> >      >>> Peter
>> >      >>>
>> >      >>>
>> >      >>>>
>> >      >>>> Best,
>> >      >>>> Yali
>> >      >>>>
>> >      >>>> -----Original Message-----
>> >      >>>> From: Peter Psenak [mailto:ppsenak@cisco.com
>> >     <mailto:ppsenak@cisco.com>]
>> >      >>>> Sent: Tuesday, March 2, 2021 5:12 PM
>> >      >>>> To: wangyali <wangyali11@huawei.com
>> >     <mailto:wangyali11@huawei.com>>; Gyan Mishra
>> >      >>>> <hayabusagsm@gmail.com <mailto:hayabusagsm@gmail.com>>;
>> Robert
>> >     Raszuk <robert@raszuk.net <mailto:robert@raszuk.net>>
>> >      >>>> Cc: Huzhibo <huzhibo@huawei.com <mailto:huzhibo@huawei.com>>;
>> >     Aijun Wang
>> >      >>>> <wangaj3@chinatelecom.cn <mailto:wangaj3@chinatelecom.cn>>;
>> >     Tony Li <tony.li@tony.li <mailto:tony.li@tony.li>>; lsr
>> >      >>>> <lsr@ietf.org <mailto:lsr@ietf.org>>; Tianran Zhou
>> >     <zhoutianran@huawei.com <mailto:zhoutianran@huawei.com>>
>> >      >>>> Subject: Re: [Lsr] New Version Notification for
>> >      >>>> draft-wang-lsr-isis-mfi-00.txt
>> >      >>>>
>> >      >>>> Yali,
>> >      >>>>
>> >      >>>> On 01/03/2021 10:49, wangyali wrote:
>> >      >>>>> Hi Peter,
>> >      >>>>>
>> >      >>>>> Many thanks for your feedback. First of all, I'm sorry for
>> >     the confusion I had caused you from my previous misunderstanding.
>> >      >>>>>
>> >      >>>>> And I want to clarify that a single and common LSDB is shared
>> >     by all MFIs.
>> >      >>>>
>> >      >>>> well, the draft says:
>> >      >>>>
>> >      >>>> "information about LSPs that transmitted in a
>> >      >>>>       specific MFI are generated to synchronize the LSDB
>> >     corresponding to
>> >      >>>>       the specific MFI."
>> >      >>>>
>> >      >>>> If the above has changed, then please update the draft
>> >     accordingly.
>> >      >>>>
>> >      >>>> thanks,
>> >      >>>> Peter
>> >      >>>>
>> >      >>>>
>> >      >>>>
>> >      >>>>>
>> >      >>>>> Best,
>> >      >>>>> Yali
>> >      >>>>>
>> >      >>>>> -----Original Message-----
>> >      >>>>> From: Peter Psenak [mailto:ppsenak@cisco.com
>> >     <mailto:ppsenak@cisco.com>]
>> >      >>>>> Sent: Sunday, February 28, 2021 8:23 PM
>> >      >>>>> To: Gyan Mishra <hayabusagsm@gmail.com
>> >     <mailto:hayabusagsm@gmail.com>>; Robert Raszuk
>> >      >>>>> <robert@raszuk.net <mailto:robert@raszuk.net>>
>> >      >>>>> Cc: Huzhibo <huzhibo@huawei.com <mailto:huzhibo@huawei.com
>> >>;
>> >     Aijun Wang
>> >      >>>>> <wangaj3@chinatelecom.cn <mailto:wangaj3@chinatelecom.cn>>;
>> >     Tony Li <tony.li@tony.li <mailto:tony.li@tony.li>>; lsr
>> >      >>>>> <lsr@ietf.org <mailto:lsr@ietf.org>>; Tianran Zhou
>> >     <zhoutianran@huawei.com <mailto:zhoutianran@huawei.com>>; wangyali
>> >      >>>>> <wangyali11@huawei.com <mailto:wangyali11@huawei.com>>
>> >      >>>>> Subject: Re: [Lsr] New Version Notification for
>> >      >>>>> draft-wang-lsr-isis-mfi-00.txt
>> >      >>>>>
>> >      >>>>> Gyan,
>> >      >>>>>
>> >      >>>>> On 26/02/2021 17:19, Gyan Mishra wrote:
>> >      >>>>>>
>> >      >>>>>> MFI seems more like flex algo with multiple sub topologies
>> >     sharing
>> >      >>>>>> a common links in a  topology where RFC 8202 MI is
>> separated at
>> >      >>>>>> the process level separate LSDB.  So completely different
>> and of
>> >      >>>>>> course different goals and use cases for MI versus MFI.
>> >      >>>>>
>> >      >>>>> I would not use the fle-algo analogy - all flex-algos operate
>> >     on top of a single LSDB, contrary to what is being proposed in MFI
>> >     draft.
>> >      >>>>>
>> >      >>>>>>
>> >      >>>>>>        MFI also seems to be a flood reduction mechanism by
>> >     creating
>> >      >>>>>> multiple sub topology instances within a common LSDB.  There
>> >     are a
>> >      >>>>>> number of flood reduction drafts and this seems to be
>> another
>> >      >>>>>> method of achieving the same.
>> >      >>>>>
>> >      >>>>> MFI draft proposes to keep the separate LSDB per MFI, so the
>> >     above analogy is not correct either.
>> >      >>>>>
>> >      >>>>> thanks,
>> >      >>>>> Peter
>> >      >>>>>
>> >      >>>>>
>> >      >>>>>>
>> >      >>>>>> Gyan
>> >      >>>>>>
>> >      >>>>>> On Fri, Feb 26, 2021 at 7:10 AM Robert Raszuk
>> >     <robert@raszuk.net <mailto:robert@raszuk.net>
>> >      >>>>>> <mailto:robert@raszuk.net <mailto:robert@raszuk.net>>>
>> wrote:
>> >      >>>>>>
>> >      >>>>>>          Aijun,
>> >      >>>>>>
>> >      >>>>>>          How multi instance is implemented is at the
>> >     discretion of a vendor.
>> >      >>>>>>          It can be one process N threads or N processes. It
>> >     can be both and
>> >      >>>>>>          operator may choose.
>> >      >>>>>>
>> >      >>>>>>          MFI is just one process - by the spec - so it is
>> >     inferior.
>> >      >>>>>>
>> >      >>>>>>          Cheers,
>> >      >>>>>>          R.
>> >      >>>>>>
>> >      >>>>>>
>> >      >>>>>>          On Fri, Feb 26, 2021 at 12:44 PM Aijun Wang
>> >     <wangaj3@chinatelecom.cn <mailto:wangaj3@chinatelecom.cn>
>> >      >>>>>>          <mailto:wangaj3@chinatelecom.cn
>> >     <mailto:wangaj3@chinatelecom.cn>>> wrote:
>> >      >>>>>>
>> >      >>>>>>              Hi, Robert:
>> >      >>>>>>
>> >      >>>>>>              Separate into different protocol instances can
>> >     accomplish the
>> >      >>>>>>              similar task, but it has
>> <https://www.google.com/maps/search/ar+task,+but+it+has?entry=gmail&source=g>
>> some deployment overhead.
>> >      >>>>>>              MFIs within one instance can avoid such
>> >     cumbersome work, and
>> >      >>>>>>              doesn’t affect the basic routing calculation
>> >     process.
>> >      >>>>>>
>> >      >>>>>>              Aijun Wang
>> >      >>>>>>              China Telecom
>> >      >>>>>>
>> >      >>>>>>>              On Feb 26, 2021, at 19:00, Robert Raszuk
>> >     <robert@raszuk.net <mailto:robert@raszuk.net>
>> >      >>>>>>>              <mailto:robert@raszuk.net
>> >     <mailto:robert@raszuk.net>>> wrote:
>> >      >>>>>>>
>> >      >>>>>>>              Hi Yali,
>> >      >>>>>>>
>> >      >>>>>>>                  If this was precise, then the existing
>> >     multi-instance
>> >      >>>>>>>                  mechanism would be sufficient.
>> >      >>>>>>>                  [Yali]: MFI is a different solution we
>> >     recommend
>> >     <
>> https://www.google.com/maps/search/lution+we+recommend?entry=gmail&source=g
>> >
>> >     to solve
>> >      >>>>>>>                  this same and valuable issue.
>> >      >>>>>>>
>> >      >>>>>>>
>> >      >>>>>>>              Well the way I understand this proposal MFI is
>> >     much weaker
>> >      >>>>>>>              solution in terms of required separation.
>> >      >>>>>>>
>> >      >>>>>>>              In contrast RFC8202 allows to separate ISIS
>> >     instances at the
>> >      >>>>>>>              process level, but here MFIs as defined must
>> >     be handled by the
>> >      >>>>>>>              same ISIS process
>> >      >>>>>>>
>> >      >>>>>>>                  This document defines an extension to
>> >      >>>>>>>                  IS-IS to allow*one standard instance*  of
>> >      >>>>>>>                  the protocol to support multiple update
>> >      >>>>>>>                  process operations.
>> >      >>>>>>>
>> >      >>>>>>>              Thx,
>> >      >>>>>>>              R.
>> >      >>>>>>>
>> >      >>>>>>>
>> _______________________________________________
>> >      >>>>>>>              Lsr mailing list
>> >      >>>>>>> Lsr@ietf.org <mailto:Lsr@ietf.org> <mailto:Lsr@ietf.org
>> >     <mailto:Lsr@ietf.org>>
>> >      >>>>>>> https://www.ietf.org/mailman/listinfo/lsr
>> >      >>>>>>
>> >      >>>>>>          _______________________________________________
>> >      >>>>>>          Lsr mailing list
>> >      >>>>>> Lsr@ietf.org <mailto:Lsr@ietf.org> <mailto:Lsr@ietf.org
>> >     <mailto:Lsr@ietf.org>>
>> >      >>>>>> https://www.ietf.org/mailman/listinfo/lsr
>> >      >>>>>>
>> >      >>>>>> --
>> >      >>>>>>
>> >      >>>>>> <http://www.verizon.com/>
>> >      >>>>>>
>> >      >>>>>> *Gyan Mishra*
>> >      >>>>>>
>> >      >>>>>> /Network Solutions A//rchitect /
>> >      >>>>>>
>> >      >>>>>> /M 301 502-1347
>> >      >>>>>> 13101 Columbia Pike
>> >      >>>>>> /Silver Spring, MD
>> >      >>>>>>
>> >      >>>>>>
>> >      >>>>>
>> >      >>>>>
>> >      >>>>>
>> >      >>>>
>> >      >>>>
>> >      >>>>
>> >      >>>
>> >      >>>
>> >      >>>
>> >      >>
>> >      >>
>> >      >>
>> >      >
>> >      >
>> >      >
>> >
>> > --
>> >
>> > <http://www.verizon.com/>
>> >
>> > *Gyan Mishra*
>> >
>> > /Network Solutions A//rchitect /
>> >
>> > /M 301 502-1347
>> > 13101 Columbia Pike
>> > /Silver Spring, MD
>> >
>> >
>>
>> --
>
> <http://www.verizon.com/>
>
> *Gyan Mishra*
>
> *Network Solutions A**rchitect *
>
>
>
> *M 301 502-134713101 Columbia Pike *Silver Spring, MD
>
> _______________________________________________
> Lsr mailing list
> Lsr@ietf.org
> https://www.ietf.org/mailman/listinfo/lsr
>