Page 1231 - 5G Basics - Core Network Aspects

Transport aspects 2

A group of 'M' successive extended ODUj bytes is de-mapped from a group of 'M' successive ODTUk.M
bytes.
NOTE 2 – For the case where the ODUj signal is output as an OTUj signal, frame alignment of the extracted extended
ODUj signal is to be recovered to allow frame synchronous mapping of the ODUj into the OTUj signal.
During a signal fail condition of the incoming ODUk/OPUk signal (e.g., in the case of an ODUk-AIS,
ODUk-LCK, ODUk-OCI condition) the ODUj-AIS pattern as specified in clause 16.5.1 is generated as a
replacement signal for the lost ODUj signal.

The values of M, m, Cm,min, Cm,max, n, Cn,min and Cn,max for ODUj into ODTUk.ts are as follows:
 ODUj _ nom _bit _ rate  1( ODUj _bit _ rate _tolerance  00006.0  ) for ODUj with j ≠ flex(GFP) (19-1a)
M  ceiling    
 (ODTUk 1 . _ nom _bit _ rate  1( ODTUk .ts _bit _ rate _tolerance ) 
M  ODUk_ bit _ rate/ ODUk. ts _ bit _ rate for ODUj with j = flex(GFP) (19-1b)

m  8  M (19-2)
 ODUj_ nom_ bit _ rate  Number _ of _ GMP_ blocks _ in _ ODTUk. ts 
c m, nom     (19-3)

 ODTUk _1. nom_ bit _ rate M 
 1  ODUj_ bit _ rate _ tolerance 
c m min,  c m, nom      (19-4)
 1  ODTUk _1. bit _ rate _ tolerance 
 1  ODUj_ bit _ rate _ tolerance 
c m max,  c m, nom     (19-5)

 1  ODTUk _1. bit _ rate _ tolerance 
C  floor c  (19-6)
m , min m , min
C  ceiling c  (19-7)
m , max m , min
n  8 (19-8)
 ODUj_ nom _ bit _ rate  Number _ of _ GMP_ blocks _ in _ ODTUk. ts 
c n, nom      (19-9)

 ODTUk _1. nom_ bit _ rate 
 1  ODUj_ bit _ rate _ tolerance 
c n min,  c n, nom      (19-10)
 1  ODTUk _1. bit _ rate _ tolerance 
 1 ODUj_ bit _ rate _ tolerance 
c n max,  c n, nom     (19-11)

 1 ODTUk _1. bit _ rate _ tolerance 
C  floor c  (19-12)
, n min , n min
C  ceiling c  (19-13)
, n max , n min
Cm,min, Cn,min (n=8), Cm,max and Cn,max (n=8) values represent the boundaries of ODUj/ODTUk.M ppm offset
combinations (i.e., min. ODUj/max. ODTUk.M and max. ODUj/min. ODTUk.M). In steady state, given
instances of ODUk/ODTUk.M offset combinations should not result in generated Cn and Cm values
throughout this range but rather should be within as small a range as possible.
NOTE – Under transient ppm offset conditions (e.g., AIS to normal signal), it is possible that Cn and Cm values outside
the range Cn,min to Cn,max and Cm,min to Cm,max may be generated and a GMP de-mapper should be tolerant of such
occurrences. Refer to Annex D for a general description of the GMP principles.
19.6.1 Mapping ODUj into ODTU2.M

Groups of M successive bytes of the extended ODUj (j = 0, flex) signal are mapped into a group of M
successive bytes of the ODTU2.M payload area under control of the GMP data/stuff control mechanism.

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