Page 1147 - 5G Basics - Core Network Aspects

Transport aspects 2

Figure 15-16 – Timing diagram example for OTUk
NOTE 3 – This time synchronization over SOTU and MOTU interface implementation does not generate event message
timestamps using a point other than the message timestamp point [ITU-T G.8260].
In this time synchronization over SOTU and MOTU interface implementation, the timestamps are
generated at a point removed from the reference plane. Furthermore, the time offset from the reference
plane is likely to be different for inbound and outbound event messages. To meet the requirement of this
subclause, the generated timestamps should be corrected for these offsets. Figure 19 in [b-IEEE 1588]
illustrates these offsets. Based on this model, the appropriate corrections are as follows:

<egressTimestamp> = <egressMeasuredTimestamp> + egressLatency
<ingressTimestamp> = <ingressMeasuredTimestamp> ─ ingressLatency
where the actual timestamps <egressTimestamp> and <ingressTimestamp> measured at the reference
plane are computed from the detected, i.e., measured, timestamps by their respective latencies. Failure to
make these corrections results in a time offset between the slave and master clocks.
15.7.3 OTUkV overhead

The functionally standardized OTUkV frame should support, as a minimum capability, section monitoring
functionality comparable to the OTUk section monitoring (see clause 15.7.2.1) with a trail trace identifier as
specified in clause 15.2. Further specification of this overhead is outside the scope of this
Recommendation.

15.8 ODU OH description

15.8.1 ODU OH location
The ODU overhead location is shown in Figures 15-17, 15-18 and 15-19.

The ODUk contains one instance of ODU overhead. The ODUCn contains n instances of ODU overhead,
numbered 1 to n (ODU OH #1 to ODU OH #n).

1137