Re: [Detnet] L2/L3 model?

I do not think so Philippe.

I do not see the PCE talking only to L3 devices and let the L3 devices set up a path through a UNI interface. The PCE needs to know the capabilities and topology of all the hops, so as to guarantee an optimized path.
Whether a hop is L2 or L3 is actually a secondary artifact from that perspective; and in practice, I expect that the L3 TSN switching will often be L2.5,  MPLS or TSCH.
>From the detnet and the 6TiSHC meetings, I gathered that:
- the IETF is forming a TEAS WG that would define a Yang data model for topologies. We could probably extend that.
- we could extend PCEP to configure and maintain the paths and related state info if we use the model whereby the PCE talks individually to the intermediate nodes
- OTOH, if we decide to set up the path hop-by-hop using a source-route indication computed by the PCE, then CCAMP may become useful, to be monitorind for new work just being started.

Cheers,

Pascal

> -----Original Message-----
> From: detnet [mailto:detnet-bounces@ietf.org] On Behalf Of Philippe Klein
> Sent: mardi 18 novembre 2014 07:15
> To: Anca Zamfir (ancaz); Erik Nordmark
> Cc: detnet@ietf.org
> Subject: Re: [Detnet] L2/L3 model?
> 
> Ana,
> Thank you for your question.
> In my humble view I am not sure we must create a single heterogeneous view of
> the network. It seems to me that we must keep both topology separated and  let
> the L3 ask the L2 to create a path with the given QoS (delay, jitter, bw...AND
> REDUNDACY if needed) constrains.
> 
> /Philippe
> 
> 
> -----Original Message-----
> From: Anca Zamfir (ancaz) [mailto:ancaz@cisco.com]
> Sent: Monday, November 17, 2014 9:32 PM
> To: Philippe Klein; Erik Nordmark
> Cc: detnet@ietf.org
> Subject: Re: [Detnet] L2/L3 model?
> 
> Hi Philippe,
> My understanding is that QoS (delay, jitter, b/w, etc) must be guaranteed for the
> end-to-end path, whether the path spans L3 only, L2 only or a mixture. One
> solution would be for PCE to get the L2 and L3 island topologies (yes, make PCE
> work at L2 with SPB + extensions which is new) and create a single
> heterogeneous view of the network. Once the path is computed, PCE can
> determine how the different segments (could be TE LSPs in L3 or multicast
> groups for L2) should be created. I think PW-s (if
> used) would be carried inside these segments and it would be good to only
> expose the label at the termination point (listener or the node that eliminates
> the duplicates). This is to avoid having to do stitching.
> There are other possibilities to explore, with some (like where L2 and L3 islands
> independently establish these paths) I am struggling with the end-to-end
> guarantee.
> 
> thanks
> -ana
> 
> On 11/17/14 8:02 PM, "Philippe Klein" <philippe@broadcom.com> wrote:
> 
> >Erik,
> >In my humble view, the L3 must only indicate the L3 router path over of
> >the L2 island with its path attributes  and let the L2 protocol select
> >the constrained path.
> >Essentially the inner L2 topology could be ignored by the L3.
> >
> >/Philippe
> >Broadcom
> >
> >Sent from my iPhone
> >
> >> On Nov 17, 2014, at 20:11, "Erik Nordmark" <nordmark@acm.org> wrote:
> >>
> >>
> >> After the BoF I realized there was one thing we didn't talk about
> >>which is what combined L2 and L3 topologies that folks have in mind.
> >> It is true that from a packet forwarding perspective both L2 and L3
> >>have queues and clocks, but the interaction with the control plane and
> >>the approach might be different for different forms of combinations.
> >>
> >> First of all we have 6TISCH which is an L3-only network.
> >>
> >> But in combined L2/L3 networks we could have at least
> >> - interconnecting L2 islands using L3
> >> - arbitrary topologies with mixtures of L2 and L3 forwarding devices
> >>
> >> A suggestion (at the mike during the BoF) was to consider pseudo-wires.
> >>That might make sense when interconnecting L2 islands.
> >> But with arbitrary topologies one could end with with a path that as
> >>a mixture of bridges and routers e.g.
> >>
> >>     Sender - B1 - B2 - R1 - B3 - B4 - B5 - R2 - R3 - Listener
> >>
> >> Are there use cases that result in such topologies/paths?
> >>
> >> Would one need one controller which is aware of both the L2 and L3
> >>devices and can pick paths (with resources) that include both?
> >> (Typically we separate the layers thus we might have a PCE which sees
> >>the L3 topology but not the L2 devices in between the routers.)
> >>
> >> I think it would be good to explore the combined L2/L3 use cases and
> >>models in more detail.
> >>
> >>   Erik
> >>
> >> _______________________________________________
> >> detnet mailing list
> >> detnet@ietf.org
> >> https://www.ietf.org/mailman/listinfo/detnet
> >
> >_______________________________________________
> >detnet mailing list
> >detnet@ietf.org
> >https://www.ietf.org/mailman/listinfo/detnet
> 
> _______________________________________________
> detnet mailing list
> detnet@ietf.org
> https://www.ietf.org/mailman/listinfo/detnet