Subject: Re: [mpls] NFFRR

From: Michael Menth <[email-masked]>
Date: Tue, 15 Jun 2021 16:43:52 +0200

Dear Kireeti,

our follow-up work
"Robust LFA Protection for Software-DefinedNetworks (RoLPS)"
got accepted for IEEE Transactions on Network and Service Management:
https://atlas.informatik.uni-tuebingen.de/~menth/papers/Menth21e.pdf

It is related to NFFRR because it defines advanced loop detection (ALD)
and avoidance in a simple manner. The concept is now implemented on the
P4-programmable Tofino target. Section VII.C reports about an experiment
to demonstrate how the prototype avoids loops.

This new version (ALD) is more straightforward than the old version
(ALDT) because we did not restrict ourselves to the (missing)
capabilities of OpenFlow anymore, P4 is more flexible. You cited ALDT in
your draft:
https://datatracker.ietf.org/doc/html/draft-kompella-mpls-nffrr-01#section-1.1

Yes, we think that some sort of that mechanism makes sense, especially
in controller-based networks.

Kind regards,

Michael

Am 02.11.2020 um 16:19 schrieb Kireeti Kompella:
> Hi Michael,
> 
> Thanks for the link to the paper.  It is cool that both attack
> the problem of loops due to multiple failures (real or perceived).
> 
> While the goals are similar, there are clearly differences in the
> approach because of different assumptions.  ALDT attempts to minimize
> false discards, at the expense of higher packet and processing
> overhead.  The NFFRR approach is far more naive, but also far more
> efficient.  It would be interesting to see how often NFFRR discards
> packets erroneously in different topologies, as opposed to LDT or ALDT. 
> The trade-offs between efficiency and correctness are harder to determine.
> 
> Sprinkled in the referenced paper in multiple places are limitations due
> to OpenFlow.  P4 is a better base for prototyping.
> 
> One question: how is an LD label recognized as such?
> 
> Thanks too for the reference to the Topology Zoo.  The topologies I
> sampled were pretty small, though.
> 
> 
> On Thu, Sep 17, 2020 at 8:01 AM Michael Menth <[email-masked]
> <mailto:[email-masked]>> wrote:
> 
>     Hi Kireeti, all,
> 
>     interesting to see this in MPLS. We've done a similar feature (Advanced
>     Loop Detection and Termination, ALDT) for destination-based forwarding
>     with LFAs and did some evaluations:
> 
>     D. Merling, W. Braun, and M. Menth: Efficient Data Plane Protection for
>     SDN, in Proceedings of the 4th IEEE Conference on Network Softwarization
>     (NetSoft), June 2018, Montreal, Canada.
>     https://atlas.informatik.uni-tuebingen.de/~menth/papers/Menth18g.pdf
>     <https://atlas.informatik.uni-tuebingen.de/~menth/papers/Menth18g.pdf>
> 
>     We've implemented a prototype on the P4-based Tofino from barefoot, a
>     paper is to come.
> 
>     Regards,
> 
>     Michael
> 
>     Am 17.09.2020 um 16:27 schrieb Kireeti Kompella:
>     > Hi All,
>     >
>     > We have a prototype implementation of NFFRR in Junos.  The packet
>     > forwarding code was easier to write using a well-known SPL rather
>     than a
>     > configured or signaled label.  This implementation is specifically for
>     > the EVPN multihoming case -- to prevent loops if the CE is down rather
>     > than a link to the CE, but the principle is the same for other
>     NFFRR cases.
>     >
>     > Given that, and the fact that the problem is real, the solution
>     > implemented and the draft reasonably comprehensive and stable, the
>     > authors request WG adoption.
>     >
>     > --
>     > Kireeti
>     >
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>     >
> 
>     -- 
>     Prof. Dr. habil. Michael Menth
>     University of Tuebingen
>     Faculty of Science
>     Department of Computer Science
>     Chair of Communication Networks
>     Sand 13, 72076 Tuebingen, Germany
>     phone: (+49)-7071/29-70505
>     fax: (+49)-7071/29-5220
>     mailto:[email-masked] <mailto:[email-masked]>
>     http://kn.inf.uni-tuebingen.de <http://kn.inf.uni-tuebingen.de>
> 
> 
> 
> -- 
> Kireeti

-- 
Prof. Dr. habil. Michael Menth
University of Tuebingen
Faculty of Science
Department of Computer Science
Chair of Communication Networks
Sand 13, 72076 Tuebingen, Germany
phone: (+49)-7071/29-70505
fax: (+49)-7071/29-5220
mailto:[email-masked]
http://kn.inf.uni-tuebingen.de