Re: [CCAMP] Overlay model framework and context

Lou Berger <lberger@labn.net> Wed, 19 December 2012 17:38 UTC

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From: Lou Berger <lberger@labn.net>
To: Daniele Ceccarelli <daniele.ceccarelli@ericsson.com>
Date: Wed, 19 Dec 2012 12:38:33 -0500
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Cc: CCAMP <ccamp@ietf.org>
Subject: Re: [CCAMP] Overlay model framework and context
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Okay. This helps .so to simplify even further, we have the following 
alternatives:
ONI = overlay customer interface.

Right?

Lou



On December 19, 2012 11:23:50 AM Daniele Ceccarelli 
<daniele.ceccarelli@ericsson.com> wrote:
> Basically yes; being fussy i would say:
>
> For the signaling+routing(normal case):
> 	LB) customer interface with signaling and routing
> 	DC) ONI
> For the UNI case:
>  	LB) customer interface with UNI
> 	DC) UNI
>
> BR
> Daniele
>
>
> >-----Original Message-----
> >From: Lou Berger [mailto:lberger@labn.net]
> >Sent: mercoledì 19 dicembre 2012 16.54
> >To: Daniele Ceccarelli
> >Cc: CCAMP
> >Subject: Re: [CCAMP] Overlay model framework and context
> >
> >Daniele,
> >	If ONI is a superset (i.e., covers all cases), what's
> >the difference.
> >So the terminology options are:
> >
> >For the signaling+routing(normal case):
> >	LB) customer interface with signaling and routing
> >	DC) ONI with signaling and routing
> >For the UNI case:
> > 	LB) customer interface with UNI
> >	DC) ONI with UNI
> >
> >Right?
> >
> >Lou
> >
> >On 12/19/2012 10:32 AM, Daniele Ceccarelli wrote:
> >>  Lou, it's just a matter of convenience.
> >>
> >> Why should is say:
> >> "customer interface/link between an OE and an OC in the
> >overlay model context supporting both signaling and routing
> >message exchange that is called UNI when only signaling is supported"
> >>
> >> ...when i could simply say: ONI? :)
> >>
> >> BR
> >> Daniele
> >>
> >>> -----Original Message-----
> >>> From: Lou Berger [mailto:lberger@labn.net]
> >>> Sent: mercoledì 19 dicembre 2012 16.09
> >>> To: Daniele Ceccarelli
> >>> Cc: CCAMP
> >>> Subject: Re: [CCAMP] Overlay model framework and context
> >>>
> >>> Daniele,
> >>> 	see below.
> >>>
> >>>
> >>> On 12/19/2012 5:56 AM, Daniele Ceccarelli wrote:
> >>>> Hi Lou,
> >>>>
> >>>> Plese find replies in line.
> >>>>
> >>>> BR
> >>>> Daniele
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: Lou Berger [mailto:lberger@labn.net]
> >>>>> Sent: lunedì 17 dicembre 2012 20.45
> >>>>> To: Daniele Ceccarelli
> >>>>> Cc: CCAMP
> >>>>> Subject: Re: [CCAMP] Overlay model framework and context
> >>>>>
> >>>>>
> >>>>> Daniele,
> >>>>> 	Thanks for getting this on-list discussion going.  I have some
> >>>>> comments and questions:
> >>>>>
> >>>>> - So what's a "client layer network" in this context?
> >Perhaps you
> >>>>> mean OC or "(overlay) customer layer"?
> >>>>
> >>>> Yes. The terms client layer and server layer are
> >>> reminescences to be corrected.
> >>>>
> >>>>>
> >>>>> - So what's a "server layer network" in this context?
> >Perhaps you
> >>>>> mean OE or "(overlay) provider layer"?
> >>>>
> >>>> Again correct
> >>>>
> >>>>>
> >>>>> - For OC, I'd thing referring back to a CE in the VPN
> >context, and
> >>>>> likewise to a PE for an OE, is helpful context.
> >>>>
> >>>> In the case of the interface we generally define the ONI as
> >>> an overlay
> >>>> interface that in a particular case is called UNI.
> >>>
> >>> I have no idea what this means.  I suspect it relates to comments
> >>> below, so will discuss there.
> >>>
> >>>> I would
> >>>> apply the same method: those nodes are called Overlay Customer and
> >>>> Overlay Edge and in the particular case of VPNs they are the
> >>> CE and PE
> >>>> respectively. What about that?
> >>>>
> >>>
> >>> How about:
> >>>
> >>> An OC is analogous to an L3VPN CE, and an OE is analogous
> >to an L3VPN
> >>> PE (with a provider based VPN).
> >>>
> >>>>>
> >>>>> - As you mention in the Appendix, (from the OC perspective)
> >>> there is
> >>>>> no difference between a virtual and real node (and
> >>> presumably link as
> >>>>> well).  Given this and your comment in 8, that the ONI
> >can take the
> >>>>> form of a UNI or include both signaling and routing (i.e., a
> >>>>> peer/I-NNI or
> >>>>> E-NNI) what value is there in introducing the ONI term?
> >>> Said another
> >>>>> way, there's no specific term for the interface between a
> >CE and PE
> >>>>> in L3VPNs, so why do we need to introduce one in this context?
> >>>>
> >>>> We gave a name to the UNI, why don't giving to the ONI?
> >>>
> >>> Because redundant/unnecessary terminology only obfuscates.
> >>>
> >>> Why not customer interface/link? This has been sufficient
> >for L3VPNs.
> >>>
> >>>>
> >>>>>
> >>>>> I think this same comment probably holds for the O-NNI
> >>> (e.g., what's
> >>>>> the name of the interface between providers which support L3VPN
> >>>>> handoffs?)...
> >>>>
> >>>> I would suggest giving a name to that interface also in
> >>> order to distinguish between an "internal" and an "external"
> >>> link when multiple overlay provider network domains are present.
> >>>>
> >>>
> >>> How about inter-provider interface/link? Again, this has been
> >>> sufficient for L3VPNs.
> >>>
> >>> Lou
> >>>
> >>>>>
> >>>>> Much thanks,
> >>>>> Lou
> >>>>>
> >>>>> On 12/17/2012 6:17 AM, Daniele Ceccarelli wrote:
> >>>>>> Dear CCAMPers,
> >>>>>>
> >>>>>> In the last weeks several off-line discussions on the
> >>>>> Overlay model framework and related works took place. Some
> >>>>> discussions led to some sort of agreemet among a small group of
> >>>>> people, some others to a set a viable options, some others
> >>> to totally
> >>>>> open issues. I tried to summarize the output of such discussions
> >>>>> below so to progress the discussions into a single thread
> >on the WG
> >>>>> ML.
> >>>>>>
> >>>>>> Please note that the aim of this mail is not to present a
> >>>>> well shaped and conclusive idea to the WG but rather to
> >provide the
> >>>>> basis for starting a discussion from a barely shaped idea
> >(step 1)
> >>>>> instead of starting it from scratch (step 0).
> >>>>>>
> >>>>>> In addition you can find attached a slide depicting a
> >>>>> proposal of the overlay scenario.
> >>>>>>
> >>>>>> Thanks,
> >>>>>> Daniele
> >>>>>>
> >>>>>> + Disclaimer:
> >>>>>>  1. Packet opto integration is often considered but the work
> >>>>> can be extented to any type of SC. Eg. TDM over LSC.
> >>>>>>
> >>>>>> + Terminology:
> >>>>>>
> >>>>>>  1. Virtual Link: A virtual link is a potential path between
> >>>>> two virtual or real network elements in a client layer
> >network that
> >>>>> is maintained/controlled in and by the server domain
> >control plane
> >>>>> (and as such cannot transport any traffic/data and protected from
> >>>>> being de-provisioned) and which can be instantiated in the
> >>> data plane
> >>>>> (and then can carry/transport/forward traffic/data) preserving
> >>>>> previously advertised attributes such as fate sharing information.
> >>>>>>  2.  Virtual Node: Virtual node is a collection of zero or
> >>>>> more server network  domain nodes that are collectively
> >represented
> >>>>> to the clients as a single node that exists in the client layer
> >>>>> network and is capable of terminating of access, inter-domain and
> >>>>> virtual links.
> >>>>>>  3.Virtual Topology: Virtual topology is a collection of one
> >>>>> or more virtual or real server network domain nodes that
> >>> exist in the
> >>>>> client layer network and are interconnected via 0 or more virtual
> >>>>> links.
> >>>>>>  4. Overlay topology:  is a superset of virtual topologies
> >>>>> provided by each of server network domains, access and
> >inter-domain
> >>>>> links.
> >>>>>>  5. Access Link: Link between OC and OE. GMPLS runs on that
> >>>>> link. It can support any of the SCs supported by the GMPLS.
> >>>>>>  6. Overlay Customer (OC): Something like the CN in RFC4208
> >>>>> teminology  but (i) receiving virtual topology from the
> >>> core network
> >>>>> and requesting the set up of one of them or (ii) requesting the
> >>>>> computation and establishment of a path accordingly to gien
> >>>>> constraints in the core network and receiving the parameters
> >>>>> characterizing such path. (ii) == UNI.
> >>>>>>  7. Overlay Edge (OE): Something like the EN in RFC4208 but
> >>>>> able to deal with (i) and (ii) above.
> >>>>>>  8. ONI : Overlay network interface: Interface allowing for
> >>>>> signaling and routing messages exchange between Overlay and  Core
> >>>>> network. Routing information consists on virtual topology
> >>>>> advertisement. When there is no routing adjacency across the
> >>>>> interface it is equivalent to the GMPLS UNI defined in 4208.
> >>>>> Signaling messages are compliant with RFC4208.
> >Information  related
> >>>>> to path carachteristics, e.g. TE-metrics, collected  SRLG,
> >>> path delay
> >>>>> etc, either passed from OE to OC via  signaling after the LSP
> >>>>> establishment in the core network or from OC to OE to be
> >>> used as path
> >>>>> computation constraints, fall  under the definition of
> >>> signaling info
> >>>>> and not routing info).
> >>>>>>  9. O-NNI (name to be found,maybe reused): Interface on the
> >>>>> links between different core networks in the overlay model
> >>>>> environment, i.e. Between border OEs. Same features of the
> >>> ONI apply
> >>>>> to this interface. Could it be an E-NNI? A ONI? A new name
> >>> is needed?
> >>>>>>
> >>>>>> + Statements
> >>>>>>  1. In the context of overlay model we are aiming to build
> >>>>> an overlay
> >>>>>> topology for the client network domains  2. The overlay
> >>>>> topology is comprised of:
> >>>>>>     a) access links (links connecting client NEs to the
> >>>>> server network domains). They can be PSC or LSC.
> >>>>>>     b) inter-domain links (links interconnecting server
> >>>>> network domains)
> >>>>>>     c) virtual topology provided by the server network
> >>>>> domains. Virtual Links + Virtual Nodes (TBD) +
> >Connectivity Matrix
> >>>>> (with a set of parameters e.g. SRLG, optical impairments,
> >delay etc
> >>>>> for each entry) describing connectivity between access links and
> >>>>> virtual links.
> >>>>>>  3. In the context of overlay model we manage  hierarchy
> >>> of overlay
> >>>>>> topologies with overlay/underlay relationships  4. In the
> >>> context of
> >>>>>> overlay model multi-layering and inter-layer relationships
> >>>>> are peripheral at best, it is all about horizontal network
> >>>>> integration  5. The overlay model assumes one instance for
> >>> the client
> >>>>> network and a separate instance for the server network and
> >>> in the ONI
> >>>>> case the server network also surreptitiously participates in the
> >>>>> client network by injecting virtual topology information into it.
> >>>>>>  6. L1VPN (and LxVPN) in general is a service provided over
> >>>>> the ONI (it falls under the UNI case as no routing
> >adjacency is in
> >>>>> place between OC and OE).
> >>>>>>
> >>>>>> + Open issues/questions
> >>>>>>
> >>>>>>  1. PCE-PCEP - do we need to include considerations about
> >>>>> PCE and PCEP into the overlay framework context?
> >>>>>>  2. BGP-LS needs to be considered
> >>>>>>  3. Should potentials be included? E.g. I2RS?
> >>>>>>
> >>>>>> + Appendix:
> >>>>>> Some notes on the Virtual Node:
> >>>>>> 1.      Virtual Link Model along, sadly, does not scale
> >>>>> because of N**2 problem. IP over ATM and single-segment PWs
> >>> have the
> >>>>> same issue, that's why people invented multi-segment PWs
> >>>>>> 2.      The only way to avoid full-mesh of Virtual Links is
> >>>>> by having intermediate nodes interconnecting Virtual Links in the
> >>>>> middle of the virtual topology
> >>>>>> 3.      These intermediate nodes cannot be real server
> >>>>> domain switches, because, generally speaking:
> >>>>>>   a)Real switches belong to different layer network;
> >>>>>>   b)Real switches are named from different naming space
> >>>>>>   c)real switches individually may not have sufficient
> >>>>> resources to terminate virtual links (while a group of real
> >>> switches
> >>>>> collectively will have)
> >>>>>>   d)Presenting a group of real switches as a single virtual
> >>>>> node have better scalability qualities
> >>>>>> 4.      Even if you map a virtual node on a single real
> >>>>> node, you need to keep in mind that real server domain
> >>> switches are,
> >>>>> generally speaking, blocking switches and as such must
> >expose their
> >>>>> connectivity matrices
> >>>>>> 5.      If you want to compute SRLG-disjoint paths that
> >>>>> could potentially go through a real server domain switch, the
> >>>>> latter's connectivity matrix must expose "internal"
> >SRLGs, so that
> >>>>> the two services traversing the switch will not
> >simultaneously fail
> >>>>> if a single internal element shared by the services fails
> >>>>>> 6.      If you walk through all cases that need to be
> >>>>> addressed when you are traffic engineering topologies
> >with blocking
> >>>>> switches, you will understand that there is absolutely no
> >>> difference
> >>>>> between a virtual node and real blocking real node.
> >>>>>> 7.      Even in case of pure VL model, client NEs connected
> >>>>> to server network domain must be upgraded so that they could
> >>>>> understand the connectivity matrices advertised by the
> >border nodes
> >>>>> describing connectivity constraints between access links
> >>> and virtual
> >>>>> links they terminate.
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> ===================================
> >>>>>> DANIELE CECCARELLI
> >>>>>> System & Technology - PDU Optical & Metro
> >>>>>>
> >>>>>> Via E.Melen, 77
> >>>>>> Genova, Italy
> >>>>>> Phone +390106002512
> >>>>>> Mobile +393346725750
> >>>>>> daniele.ceccarelli@ericsson.com
> >>>>>> www.ericsson.com
> >>>>>>
> >>>>>> This Communication is Confidential. We only send and receive
> >>>>> email on
> >>>>>> the basis of the term set out at
> >www.ericsson.com/email_disclaimer
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> _______________________________________________
> >>>>>> CCAMP mailing list
> >>>>>> CCAMP@ietf.org
> >>>>>> https://www.ietf.org/mailman/listinfo/ccamp
> >>>>>>
> >>>>>
> >>>>
> >>>>
> >>>>
> >>>
> >>
> >>
> >>
> >