RE: Lambda LSP establishment

["manoj juneja" <manojkumarjuneja@hotmail.com>]

Hi Eric,
          I fully support ur idea of having an informational draft
explaining different scenarios of SDH/SONET LSP establishment. The
concept of hierarchy is clear in case of SDH/SONET. What about the LSC
or FSC interfaces ?
2-3 days back john responded to my question on lambda hierarchy that a
lambda LSP can be advertised as a FA with different switching type (say
TDM) and then a TDM LSP can be tunneled over a lambda LSP. I am
interested in knowing the list of such scenarios in case of LSC or FSC
LSP advertised as a FA and its different combinations of switching
capabilities as these things are not expalined anywhere.
When a head or tail end of LSP advertises it as a FA then how the
multiplexing capabilities (like can switch VC-4 but not VC-3 etc.) of
the FA are decided ?

Regards,
manoj.

>From: "Mannie, Eric" <Eric.Mannie@ebone.com>
>To: 'Heiles Juergen ' <Juergen.Heiles@icn.siemens.de>, ''John Drake' '  
><jdrake@calient.net>, 'Maarten Vissers ' <mvissers@lucent.com>, 'manoj 
>juneja ' <manojkumarjuneja@hotmail.com>
>CC: "'ccamp@ops.ietf.org '" <ccamp@ops.ietf.org>
>Subject: RE: Lambda LSP establishment
>Date: Thu, 13 Dec 2001 18:56:31 +0100
>
>Hi All,
>
>A few comments,
>
> >In MPLS the FA establishes "virtual" layer networks. In GMPLS the layer
>networks already exist (SDH HO/LO-VCs, RS, MS, G.709 ODUs, OCh, OMS, OTS). 
>A
>FA basically corresponds to a real trail in a circuit switched network.
>
>Eric: ...and this trail is setup dynamically using GMPLS. That's the
>interest. One can think of SDH/SONET FAs as shortcuts or express-routes.
>
> >One special thing about the SDH label is, that it includes a hierarchy as
>it identifies the lower order VC in a higher order VC in a STM-N signal.
>Note that this is somehow in contradiction with a statement in the GMPLS
>signaling document which says
>
> >"A Generalized Label only carries a single level of label, i.e., it is
>    non-hierarchical.  When multiple levels of label (LSPs within LSPs)
>    are required, each LSP must be established separately, see [MPLS-
>    HIERARCHY]."
>
>No, hierarchy of labels is not hierarchy of layers. And even one should 
>have
>a common definition of what means a "layer". This text says that we cannot
>have multiple embedded labels, e.g. one label containting a label stack.
>This is a signaling stuff that doesn't imply anything on the transport
>plane.
>
>Now, a label identifies ONE LSP at an interface. This LSP can be HO or LO 
>in
>SDH. The label can be fully specified or partially specified, depending on
>the context where the LSP is established.
>
>E.g. when an LSP is established over a FA, the highest part of the LSP 
>label
>is not relevant. When the FA LSP is established the lowest part of the FA
>LSP label is not relevant.
>
>If a low order LSP is established without any higher order FA, the label is
>fully specified. As you said the link is indeed the "ultimate FA" in that
>case. Except that from the routing point of view a link and an FA are two
>different things. There is a routing adjacency "over" a link but not over a
>FA.
>
>The SDH/SONET label just includes what you need to include in each 
>scenario.
>
>Moreover, the label MUST be interpreted according to the type of interface
>for which it is used. It is possible to code two labels having the same
>value but a complete different meaning. Labels are context sensitive of
>course.
>
>For instance, an LSP over an STM-0 interface or over a FA will have the
>highest part set to zero, and could possibly have the same lowest part. You
>cannot understand what means the label without knowning the detail of the
>interface. In that case, the interface is either an STM-0 interface or a
>VC-3 FA. And of course that FA and STM-0 interface are two different 
>things,
>but from the LSP point of view, in both cases what it wants is a VC-3 in
>which it can be multiplexed.
>
>Hope this helps.
>
>I start to wonder if we should have an informational draft describing
>different scenarios of SDH/SONET LSP establishment. That could complement
>the SDH/SONET signaling drafts and the GMPLS architecture. That could solve
>many terminology and modeling issues.
>
>Kind regards,
>
>Eric
>
>-----Original Message-----
>From: Heiles Juergen
>To: 'John Drake'; Maarten Vissers; manoj juneja
>Cc: ccamp@ops.ietf.org
>Sent: 12/13/01 11:15 AM
>Subject: RE: Lambda LSP establishment
>
>Let me express my understanding of FAs in MPLS/GMPLS, please correct me
>if I am wrong. I have also some questions related to the label
>generation and interactions between layer networks.
>
>The label in MPLS is local to the link between two adjacent MPLS
>switches, it indicates a LSP in this link. This link is therefore the
>ultimate FA. An already established LSP between two MPLS switches, which
>don't have to be adjacent, can be used to transport/tunnel other LSPs
>between this two nodes. This already established LSP generates a virtual
>adjacency between the two nodes, the FA. As several LSPs can use this FA
>it is also a kind of virtual multiplexing.
>If you compare it with a circuit switched network the FA is a server
>layer trail that provides transport (a link connection) for one or more
>client layer signals.
>In MPLS the FA establishes "virtual" layer networks. In GMPLS the layer
>networks already exist (SDH HO/LO-VCs, RS, MS, G.709 ODUs, OCh, OMS,
>OTS). A FA basically corresponds to a real trail in a circuit switched
>network.
>In GMPLS the label is also local to the link between the two devices
>that perform the switching. For example for SDH the VC-N is identified
>by the STM-N link/port and the SUKLM number according to
>draft-ietf-ccamp-gmpls-sonet-sdh-02.txt. The STM-N port is identified by
>the interface ID (I am not sure on this) and SUKLM is the SDH label that
>locates the VC within the STM-N.
>From just the SDH viewpoint the STM-N connection is the ultimate server
>trail/FA. However the STM-N signal could be transported over a Optical
>Channel or G.709 ODU. The OCh or ODU can already start in the equipment
>that performs the VC-N switching. So the STM-N signal is not the port,
>but the WDM signal is the port and the STM-N signal makes use of a OCh
>or ODU server layer trail. This server layer trail can be established
>via management or using GMPLS.
>Can someone explain how a label for a VC-4 is generated in this case
>(pre-established OCh or ODU trail via management or setup using GMPLS).
>This interaction between the different technologies/labels need in my
>view some further explanation.
>
>One special thing about the SDH label is, that it includes a hierarchy
>as it identifies the lower order VC in a higher order VC in a STM-N
>signal. Note that this is somehow in contradiction with a statement in
>the GMPLS signaling document which says
>"A Generalized Label only carries a single level of label, i.e., it is
>    non-hierarchical.  When multiple levels of label (LSPs within LSPs)
>    are required, each LSP must be established separately, see [MPLS-
>    HIERARCHY]."
>Following this statement each layer should have its own label
>independent of server layers.
>The combination of hierarchies in labels is based on technology (e.g.
>SDH, Sonet, G.709 ODU) but has in my view no real technical reason. The
>SDH label for example fits to standard STM-N signals, but not to sub-STM
>signals.
>For the SDH the full SUKLM number is used if a e.g. VC-12 is located in
>relation to a STM-N interface. If it is located in relation to a VC-4
>(the VC-4 is in this case a FA) SUK are set to 0. For me it is not clear
>in which case I use the first and in which case I use the second case as
>a VC-4 trail is always needed for a VC-12 connection. This VC-4 could be
>established using management or GMPLS. However it should have no
>influence on the label.
>Some more information is needed in my view in this area.
>
>
>Juergen
>
>
> > -----Original Message-----
> > From: John Drake [mailto:jdrake@calient.net]
> > Sent: Wednesday, December 12, 2001 6:54 AM
> > To: Maarten Vissers; manoj juneja
> > Cc: ccamp@ops.ietf.org
> > Subject: RE: Lambda LSP establishment
> >
> >
> > fortunately, this is just your opinion
> >
> > -----Original Message-----
> > From: Maarten Vissers [mailto:mvissers@lucent.com]
> > Sent: Tuesday, December 11, 2001 9:31 PM
> > To: manoj juneja
> > Cc: ccamp@ops.ietf.org
> > Subject: Re: Lambda LSP establishment
> >
> >
> > Manoj,
> >
> > Forget the FA stuff, it is not appropriate in circuit
> > networks. It only
> > applies
> > to MPLS. We should remove it when it is used in relation with PDH,
> > SDH/SONET,
> > OTN and pre-OTN. The text in sdh-sonet draft should state
> > that if there is a
> > LOVC link (IETF: link bundle/TE link) then the LOVC signals
> > use a label with
> > "00KLM".
> >
> > Regards,
> >
> > Maarten
> >
> > manoj juneja wrote:
> > >
> > > Hi Marteen,
> > >             The concept of FA is mentioned for SDH/SONET in
> > gmpls-sdh
> > > -sonet draft. It says that if u have a HOVC trail as a FA
> > (advertized
> > > as a link) then u can allocate the lower level signals in
> > it by making
> > > the higher bits of label as 0s (i.e. S and U}. This is fine
> > for the same
> > > technology. What about the case where the TDM LSP has to be tunneled
> > through
> > > the Lambda LSP ? What will be the form of label (i.e.
> > {SUKLM} or lambda
> > > etc.) ?
> > >
> > > Regards,
> > > manoj.
> > >
> > > >From: Maarten Vissers <mvissers@lucent.com>
> > > >To: manoj juneja <manojkumarjuneja@hotmail.com>
> > > >CC: ccamp@ops.ietf.org
> > > >Subject: Re: Lambda LSP establishment
> > > >Date: Tue, 11 Dec 2001 15:56:41 +0100
> > > >
> > > >Manoj,
> > > >
> > > >You refer to one wavelength to be available between A-E without
> > wavelength
> > > >conversion capability. This suggests that you operate at
> > the OCh layer
> > > >network.
> > > >Then you specify the capacity of the 4 OCh link
> > connections (A-B, B-C,
> > C-D,
> > > >D-E)
> > > >to be "C". Say that C is about 10 Gbit/s. You then assume
> > that there is a
> > > >request for an OCh signal with capacity C/4 (e.g. 2.5
> > Gbit/s) between C
> > and
> > > >E.
> > > >The result is that the OCh link connections C-D and D-E
> > are transporting
> > > >the OCh
> > > >signal (of e.g. 2.5G). These OCh link connections are now
> > in service and
> > > >not
> > > >longer available to an other OCh connection request. I.e.
> > a request for
> > an
> > > >OCh
> > > >connection between A and E will be rejected.
> > > >
> > > >FAs are not applicable in the circuit layers. IF there is
> > a trail in
> > server
> > > >layer X, then there is a link in its client layer Y. X and
> > Y are thus
> > > >different
> > > >layer networks and signals.
> > > >
> > > >If C-E is a "FA", then in an OTN the C-E connection would
> > be an OCh trail
> > > >supporting an ODUk (k=1 if OCh is 2G5) link with a single link
> > connection.
> > > >
> > > >Note a FA in MPLS creates essentially a MPLS sublayer
> > network. Such is
> > not
> > > >possible in the SDH/SONET, OTN, PDH or ATM technologies.
> > > >
> > > >Regards,
> > > >
> > > >Maarten
> > > >
> > > >OCh link connections
> > > >
> > > >manoj juneja wrote:
> > > > >
> > > > > Hi All,
> > > > >         If I have 5 nodes A, B, C, D and E connected as
> > shown. Assume
> > > > > that only one wavelength is available on the path A to E (no
> > wavelength
> > > > > conversion capability is there on the complete path).
> > Let the capacity
> > > > > of the wavelength be C. Further assume a request arrives for
> > connection
> > > > > from node C to E for a line capacity of C/4. This
> > request will be
> > > > > successful as we have available wavelength. Now If
> > another request
> > > > > comes at node A to establish another connection from
> > node A to node E
> > > > > via nodes {A,B,C,D,E} for a line capacity of C/4.
> > Should this request
> > > > > be successful as we have already allocated the wavelength ?
> > > > >
> > > > > If the previous connection from C to E of capacity C/4 had been
> > > > > advertised as a FA, in that case will the IInd request succeed ?
> > > > >
> > > > > If the previous connection from C to E of capacity C/4
> > had not been
> > > > > advertised as FA then what will be the fate of IInd connection ?
> > > > >
> > > > >        A <--> B <---> C <----> D <---> <----> E
> > > > >
> > > > > Regards,
> > > > > manoj.
> > > > >
> > > > >
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