[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: 答复: Lambda LSP establishment
Rick,
What happens if the node or interface supports multiple
switching/multiplexing capabilities ?
>From: "rick king" <jingrq@sohu.com>
>To: "manoj juneja" <manojkumarjuneja@hotmail.com>
>CC: <ccamp@ops.ietf.org>
>Subject: 答复: Lambda LSP establishment
>Date: Fri, 14 Dec 2001 09:54:51 +0800
>
>I think the multiplexing capabilities of the FA is decided by the
>multiplexing/switching capabilities
>of the two LSRs connected by this FA. right?
>
>rick
>----------------------------------------------------------
>发送时间: 2001年12月14日 2:45
>收件人: Eric.Mannie@ebone.com; Juergen.Heiles@icn.siemens.de;
>jdrake@calient.net; mvissers@lucent.com.
>抄送: ccamp@ops.ietf.org
>主题: RE: Lambda LSP establishment
>
>
>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.
> > > > > >
> > > > > >
> > > _________________________________________________________________
> > > > > > Get your FREE download of MSN Explorer at
> > > > >http://explorer.msn.com/intl.asp
> > > > ><< mvissers.vcf >>
> > > >
> > > > _________________________________________________________________
> > > > Send and receive Hotmail on your mobile device:
> >http://mobile.msn.com
>
>
>_________________________________________________________________
>Send and receive Hotmail on your mobile device: http://mobile.msn.com
>
>
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp.