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Re: Moving right along ... Switching Type
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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