320 STM??“16 1,344 DS??“1s or 48 DS??“3s 1,008 E1s or 16 E4s
STS??“192, OC??“192 9,953.280 STM??“64 5,376 DS??“1s or 192 DS??“3s 4,032 E1s or 64 E4s
STS-768, OC-768 39,813.120 STM-256 21,504 DS-1s or 768 DS3s 16,128 E1s or 256 E4s
* The designation OC-N refers to the optical signal that corresponds to the STS-N electrical signal.
TABLE 11.1 Signal Rates and Capacities for SONET and SDH
Figure 11.1 SPE inside two STS-1 frames
9 rows
9 rows
90 Columns
Transport overhead
125 ?µs
250 ?µs
Start of STS-1 SPE
STS-1 SPE STS-1 SPE
STS POH Column
302 Chapter 11
?– It supports strong OAM capabilities. Over 5 percent of the SONET bandwidth is devoted
to OAM. Fundamental capabilities include alarm surveillance, performance
monitoring and thresholding, and loopback functions; these cover virtually every
aspect of the SONET network. Nearly 150 pages of GR-253-CORE [3], Telcordia??™s
seminal SONET generic requirements specification, address OAM capabilities.
?– It provides a rapid protection mechanism. The SONET specifications require protection
switching within 50 ms and include fundamental mechanisms to enable
this. For example, the SONET overhead includes bytes (the K1 and K2 bytes) that
communicate protection switching information between systems on either side of
the SONET interface.
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