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Re: Moving right along ... Switching Type
Dimitri,
Juergen's example 1 shows (as far as I understand) two ports on a larger ODU
cross connect equipment. Both ports connect to the ODU fabric. Both ports are
part of one ODU LINK; this ODU LINK contains 8 ODU1 Link Connections.
The upper port maps the 4 ODU1 signals into 4 OTU1 signals. Then the 4 OTU1
signals are mapped into OCh signals and then multiplexed into the OTM-4.1
signal.
The lower port multiplexes the 4 ODU1 signals into an ODU2 signal. The ODU2
signal is mapped into an OTU2 signal and then this OTU2 signal is output as an
OTM-0.2 signal.
All 8 ODU1 ports on the ODU fabric are equal from a routing perspective.
So all 8 ODU1 ports at the ODU fabric are endpoints of ODU1 link connections.
They should be represented in the same manner. I.e. they are all "G.709 ODU1"
types.
"G.709 OCh" is not relevant here (it is not within the scope of the ODU1 layer).
Within the OCh layer network, there is an OCh LINK with 5 OCh link connections.
Those OCh link connection carry OCh Permanent Connections (PC); i.e. OCh signals
in this example are non-switched ones. Another reason why there is no OCh
related signalling present.
----
Example 2 shows an example of the serial compound link we addressed before. The
non-GMPLS/ASON node is totally irrelevant... there is an ODU link with 4 ODU1
(serial compound) link connections between nodes A and C. These link connections
are to be identified by "G.709 ODU1" type. Simple and straigthforward... works
always... :-)
Regards,
Maarten
Dimitri Papadimitriou wrote:
>
> Juergen, see inline...
>
> Heiles Juergen wrote:
> >
> > Following the discussion on the Switching Type and looking on the proposed G.709 extensions for GMPLS I would like to get some feedback on the examples shown below.
> > How to handle the examples concerning label request and returned label is important for my understanding of GMPLS.
> > The examples are based on G.709 ODUs. A ODU can be transported via WDM systems or using TDM in a higher bit rate ODU. So we can have a mixture of both methods.
> >
> > Juergen
> >
> > Example 1:
> >
> > Two network elements A and B with ODU1 cross-connect are interconnected by two types of signals.
> > - a four channel WDM OTM-4.1 interface with 4 optical channels each carrying an OTU1/ODU1
> > - a single channel OTM-1.2 with one optical channel carrying a OTU2/ODU2 and 4 ODU1 multiplexed into the ODU2.
> >
> > ----------------- ----------------
> > NE A + + NE B
> > + +
> > ODU1 ----- + + ----- ODU1
> > 1 o---+ + + OTM-4.1 + + +---o 1
> > 2 o---+ w + + 4xOCh with OTU1/ODU1 + + W +---o 2
> > + D +--------------------------------+ D +
> > 3 o---+ M + + + + M +---o 3
> > 4 o---+ + + + + +---o 4
> > ----- + + -----
> > + +
> > ODU1 ----- + + ----- ODU1
> > 5 o---+ + + OTM-0.2 + + +---o 5
> > 6 o---+ T + + 1xOCh with OTU2/ODU2 + + T +---o 6
> > + D +--------------------------------+ D +
> > 7 o---+ M + + with 4 ODU1 + + M +---o 7
> > 8 o---+ + + + + +---o 8
> > ----- + + -----
> > + +
> > ----------------- -----------------
> >
> > Now setting up a ODU1 connection between A and B. 8 ODU1 connections are available, 4 using WDM technology and 4 using TDM technology.
> > For the connection itself I don't care which of the 8 is used and I don't care about the specific technology.
> > How does the label request from NE a to NE B look like?
> > - the LSP encoding type is "G.709 digital path layer"
> > - the signal type is ODU1
> > - but what is the switching type "TDM" or "Lambda"? Both are available.
>
> Both entities aren't ODU1 switches ? i think you have indicate in the
> picture here "the interface multiplexing" capabilities not the switching
> ones.
>
> So I guess that these devices are both ODU1 switches. Therefore, if
> the switching type is used (notice that it is not necessary here since
> there is only one switching capability assigned to the "end of the
> link") the switching will be TDM
>
> The differences comes from the Encoding type in the first case
> (upper link) it will be G.709 OCh (WDM interface) in the second
> case G.709 ODUk (TDM interface)
>
> > Furthermore what kind of label is returned by NE B to NE A?
> > - for ODU 5 to 8 a "G.709 digital path layer label" with signal type ODU1 and a indication of the time slot within the ODU2
> > - but how about ODU1 to 4, a G.709 OCh signal type with the indication of the wavelength is not correct.
> > or is each ODU 1 to 4 seen as individual link?
>
> In such a case (for the OTM4.1) each of the OCh will have a dedicate ID
> that will be included within the request: setup of an ODU1 LSP
> - LSP encoding type: G.709 digital path layer
> - signal type: ODU1
> - switching type: "TDM" (not necessary)
> - If_Index: 1 (for instance to indicate the first optical channel)
>
> > Example 2:
> >
> > NE A and NE C that provide ODU1 cross-connections are interconnected via NE B that is not GMPLS aware and that performs a conversion between WDM and TDM multiplexing.
> > - between NE A and NE B a four channel WDM OTM-4.1 signal is used with 4 optical channels, each carrying a OTU1/ODU1.
> > - between NE B and NE C a single channel OTM-0.2 signal is used with one optical channel carrying a OTU2/ODU2 with 4 ODU1 multiplexed into the ODU2.
> >
> > ------------- ---------------- -------------
> > NE A + + NE B + + NE C
> > + + ODU1 + +
> > ODU1 ----- + + ----- ----- + + ----- ODU1
> > 1 o--+ + + OTM-4.1 + + +--+ + + OTM-0.2 + + +--o 1
> > 2 o--+ w + + 4xOCh with + + W +--+ T + + 1xOCh with + + T +--o 2
> > + D +----------------+ D + + D +-----------------+ D +
> > 3 o--+ M + + OTU1/ODU1 + + M +--+ M + + OTU1/ODU1 + + M +--o 3
> > 4 o--+ + + + + +--+ + + with 4 ODU1 + + +--o 4
> > ----- + + ----- ----- + + -----
> > + + + +
> > ------------- ---------------- -------------
> >
> > Again what is the switching type of the label request from NE A to NE C (TDM or Lambda)?
> > And what is the returned label from NE C to NE A?
>
> Just to be sure in the above example i guess you ment for the second
> link 1x0Ch with OTU2/ODU2 with 4 ODU1 since having TDM
>
> Since device A, B and C are all ODU1 switches the switching will be
> always
> TDM (if this field is used cfr. the remark indicated here above).
> Remember
> here that TDM is a shortcut to specify switching of all the digital
> switching
> layers supporting TDM capabilities (this includes VC-3/VC-4/ODUk/etc.)
>
> The relative complexity in the second example shown here above arise
> more from
> the interconnection of GMPLS to non-GMPLS capable devices (in addition
> performing
> conversion of the encoding type) rather than the "switching type" issue.
>
> It reminds me Zhi's discussion on GMPLS to non-GMPLS communication here
> addind that your transmission competences it gives a very nice example.
>
> Briefly LSR A sees ODU mapping while C sees ODU multiplexing such that
> building the label association is needed as additional mechanisms here.
>
> - dimitri.
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