Specifications

20 Chapter 3 Network Feature Compatibility
Comparative
Terminology
for SONET and
SDH
The following table provides you with a short list of terms as they relate to the SONET
and SDH network feature sets.
Table 2 SONET and SDH Comparative Terminology
Term SONET Network SDH Network
1+1 ASP/MSP 1 plus 1 Automatic Protection Switch
(1+1 APS)
1 plus 1 Multiplex Section Protection
(1+1 MSP)
BLSR/MS-SPRing Bidirectional Line Switched Ring
(BLSR)
Multiplex Section Shared Protection
Ring (MS-SPRing)
APS/MSP Automatic Protection Switch (APS) Multiplex Section Protection (MSP)
Broadband DCS Broadband Digital Cross-connect
(B-DCS)
n/a
DS1/E1 Digital Signal Level 1 (DS1)
Note: T-carrier T1 equivalent.
European Level 1 (E1)
Note: E-carrier framing specification.
DS3/E3 Digital Signal Level 3 (DS3)
Note: T-carrier T3 equivalent.
European Level 3 (E3)
E-carrier framing specification.
EC-1 Electrical Carrier Level 1
Note: EC-1 is the STS-1 equivalent.
n/a
Line/Multiplex
Section
Line Multiplex Section
OC-N/STM-N Optical Carrier (OC) Level N (OC-N) Synchronous Transfer Mode Level N
(STM-N)
OC-12/STM-4 OC Level 12 (OC-12) STM Level 4 (STM-4)
OC-192/STM-64 OC Level 192 (OC-192) STM Level 64 (STM-64)
Section/
Regenerator Section
Section Regenerator Section
SONET/SDH Synchronous Optical Network
(SONET)
Synchronous Digital Hierarchy (SDH)
STS/STM Synchronous Transport Signal (STS) Synchronous Transfer Mode (STM)
STS-1/TU-3 STS Level 1 (STS-1) Tributary Unit (TU) Level 3 (TU-3)
STS-1/TUG-3 STS Level 1 (STS-1) TU Group Level 3 (TUG-3)
VT-1.5/VC-11 VT Level 1.5 (VC-1.5) Virtual Container (VC) Level 11
(VC-11)
VT-2/VC-12 VT Level 2 VC Level 12
STS/VC Synchronous Transport Signal (STS) Virtual Container (VC)
STS-1/AU-3 STS Level 1 (STS-1) Administrative Unit Level 3 (AU-3)
STS-1/VC-3 STS Level 1 (STS-1) VC Level 3 (VC-3)