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I-D_in_xml/draft-ietf-ccamp-optical-impairment-topology-yang-07 - 3R regen.txt

@@ -864,32 +864,32 @@ Internet-Draft    Opt. Impairment-Aware Topo YANG Model        July 2021
 
 2.6.  3R Regenerators
 
-   Optical transponders belonging to a ROADM node are usually used to
-   terminate a layer 0 tunnel (layer 0 service) in the WDM layer.  If,
-   however, no optical path can be found from the source to the
-   destination that is optically feasible due to the optiocal
-   impairments, a 3R regenerator is needed for regenerating the optical
-   signal in an intermediate node.  A functional description of an
-   optical 3R regeneratator can be found in [G.680], section 7.6.
-   Following this description, a 3R regenearator is considered as layer
-   0 entity because it only terminates the modulated optical signal and
-   processes the FEC for correcting any bit errors that may be present
-   in the digital signal after the (coherent) demodulation of the
-   optical signal (FEC termination in receive direction and FEC re-
-   creation in transmit direction).  Apart from the error correction,
-   there is no processing of the digital signal, i.e., the payload of
-   the signal is not processed and passed transparently from the
-   receiver including the demodulator to the transmitter including the
-   modulator.  The end-to-end layer 0 tunnel is subdivided into 2 or
-   more segments between the source transponder and the destination
-   transponder terminating the layer 0 tunnel when the signal passes one
-   or more 3R regenerators.
-
-   3R regenerators are usually realized by a pair of optical
-   transponders, which are described in Section 2.5 above.  If a pair of
-   optical transponders is used to perform a 3R regeneratator function,
-   two different configurations are possible involving the pair of
-   optical transceivers of the two optical transponders:
+   Optical transponders are usually used to terminate a layer 0 tunnel
+   (layer 0 service) in the WDM layer.  If, however, no optical path can
+   be found from the source transponder to the destination transponder
+   that is optically feasible due to the optical impairments, one or
+   more 3R regenerators are needed for regenerating the optical signal
+   in intermediate nodes.  The term "3R" regenerator means:
+   reamplification, reshaping, retiming.  As described in [G.807],
+   Appendix IV, a 3R regenerator terminates the OTSi and generates a new
+   OTSi.  Depending on the 3R regenerator capabilities, it can provide
+   functions such as carrier frequency translation (carrier-frequency),
+   changes in the modulation scheme (modulation-type) and FEC (FEC-type)
+   while passing through the remaining OTSi payload (client signal and
+   related overhead).
+
+   The 3R regeneartion compound function is illustrated in section 10.1
+   of [G.798.1], and sections 10.3 and 10.4 provide examples of a ROADM
+   architecture and a photonic cross-connect architecture including 3R
+   regenerators.  Based on the provided functionality, 3R regenerators
+   are considered as topological layer 0 entities because they are
+   needed for layer 0 path computation in case the optical impairments
+   make it impossible to find an optically feasible end-to-end path from
+   the source transponder to the destination transponder without 3R
+   regeneration.  When an end-to-end path includes one or more 3R
+   regenerators, the corresponding layer 0 tunnel is subdivided into 2
+   or more segments between the source transponder and the destination
+   transponder terminating the layer 0 tunnel.
 
 
 
@@ -898,6 +898,12 @@ Lee, et al.             Expires January 13, 2022               [Page 16]
 Internet-Draft    Opt. Impairment-Aware Topo YANG Model        July 2021
 
 
+   3R regenerators are usually realized by a pair of optical
+   transponders, which are described in Section 2.5 above.  If a pair of
+   optical transponders is used to perform a 3R regeneratator function,
+   two different configurations are possible involving the pair of
+   optical transceivers of the two optical transponders:
+
    o  The two transponders can be operated in a back-to-back
       configuration where the transceiver of each optical transponder
       receives and transmits the optical signal from/to the same segment
@@ -939,12 +945,6 @@ Internet-Draft    Opt. Impairment-Aware Topo YANG Model        July 2021
    WSS separates the incoming light input spectrally as well as
    spatially, then chooses the wavelength that is of interest by
    deflecting it from the original optical path and then couple it to
-   another optical fibre port.  WSS/Filter is internal to ROADM.  So
-   this document does not model the inside of ROADM.
-
-
-
-
 
 
 
@@ -954,6 +954,9 @@ Lee, et al.             Expires January 13, 2022               [Page 17]
 Internet-Draft    Opt. Impairment-Aware Topo YANG Model        July 2021
 
 
+   another optical fibre port.  WSS/Filter is internal to ROADM.  So
+   this document does not model the inside of ROADM.
+
 2.8.  Optical Fiber
 
    There are various optical fiber types defined by ITU-T.  There are
@@ -1002,9 +1005,6 @@ Internet-Draft    Opt. Impairment-Aware Topo YANG Model        July 2021
 
 
 
-
-
-
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 Internet-Draft    Opt. Impairment-Aware Topo YANG Model        July 2021
@@ -3333,8 +3333,8 @@ Internet-Draft    Opt. Impairment-Aware Topo YANG Model        July 2021
               multiplexing applications with single channel optical
               interfaces", ITU-T Recommendation G.698.2, November 2018.
 
-   [G.680]    "Physical transfer functions of optical network elements",
-              ITU-T Recommendation G.680, July 2007.
+   [G.798.1]  "Types and characteristics of optical transport network
+              equipment", ITU-T Recommendation G.798.1, January 2013.
 
 Appendix A.  Contributors