Transcript Document

SONET/SDH Introduction –
What is the Difference Between SONET and SDH?
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Why SDH/SONET?
• SDH (Synchronous Digital Hierarchy) and SONET (Synchronous
Optical NETwork) are standards for interfacing optical networks.
• Simple multiplexing processes
• Easy access to various signals in a multiplexed high bit rate
signal
• A flexible and efficient way of networking
– Network Distribution: Add/Drop capability
– Network survivability: APS (Automatic Protection Switching)
– Traffic Cross connection: capacity management, bandwidth
management and protection route diversity
• Support advance Network Management System (OAM&P) –
Overhead bits for Fault, Configuration, Performance Monitoring,
Security and Accounting management
• Standardized interface can support multi vendor interworking,
international connection and many different services; i.e. ATM,
IP
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SONET/SDH Digital Hierarchy
Optical
Level
SONET
Electrical
Level
SDH
Equivalent
Line Rate
(Mbps)
Payload
Rate
(Mbps)
Overhead
Rate
(Mbps)
SONET
Capacity
SDH
Capacity
OC-1
STS-1
–
51.840
50.112
1.728
28 DS-1s or
1 DS-3
21 E1s
OC-3
STS-3
STM-1
155.520
150.336
5.184
84 DS-1s or
3 DS-3s
63 E1s or
1 E4
OC-12
STS-12
STM-4
622.080
601.344
20.736
336 DS-1s or
12 DS-3s
252 E1s or
4 E4s
OC-48
STS-48
STM-16
2488.320
2405.376
82.944
1,344 DS-1s or
192 DS-3s
1,008 E1s or
16 E4s
OC-192
STS-192
STM-64
9953.280
9621.504
331.776
5,376 DS-1s or
192 DS-3s
4,032 E1s or
64 E4s
Note:
Although an SDH STM-1 has the same bit rate as the SONET STS-3, the two signals contain different frame structures.
STM = Synchronous Transport Module (ITU-T)
STS = Synchronous Transfer Signal (ANSI)
OC = Optical Carrier (ANSI)
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SDH and SONET Bit Rate
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SDH
Bit Rate
SONET
STM-0
51Mb/s
OC-1
STM-1
155Mb/s
OC-3
STM-4
622Mb/s
OC-12
STM-16
2.48Gb/s
OC-48
STM-64
9.95Gb/s
OC-192
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(STS-1)
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What is different about SDH vs. SONET?
• Together they are a set of global standards that interface
equipment from different vendors. SDH is basically the
international version of SONET, and SONET can be thought of
as the North American version of SDH.
• There are some slight differences between SONET and SDH.
• The main differences are in the basic SDH and SONET frame
formats, but SDH and SONET are essentially identical beyond
the STS-3 signal level. The base signal for SONET is STS-1 and
the base signal for SDH is STM-1. STS-3c is equivalent to STM-1
and the lower tributaries can be mapped interchangeably
between the two formats from that point on.
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What is different about SDH vs. SONET?
(Cont’)
• In SDH, both electrical and optical signals are referred to as STM
signals.
• In SONET, however, electrical signals are called STS and optical
signals are referred to as OC.
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SONET
• Defined by Bellcore and ANSI T1.X committees
Base rate (High Order) is 51.84Mbps (STS-1)
STS-1 Synchronous Payload Envelope (SPE) =
50.112M used for carrying tributaries or a DS3 signal
Tributaries (Low Order) used for SONET are:
VT1.5 (SPE Trib) = 1.728M for carrying DS1 (1.544)
VT2 (SPE Trib) = 2.304M for carrying CEPT (E1, 2.048)
VT6 (SPE Trib) = 6.912M, Never “formalized” same
rate as VT Group
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SONET Hierarchy
STS-N
x1
STS-N
SPE
xN
STS-1
SPE
Tributaries of Base Signal
(Low Order Payloads)
Data
x1
DS3
Broadband STS-N Payloads
(High Order Payloads)
x7
VT Group
x1
VT 6
VT6
SPE
VT 2
VT2
SPE
VT 1.5
VT1.5
SPE
x3
x4
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E1
DS1
8
STS-1 Frame with VT Mapping
3 bytes
3
1
87 bytes
Section OH
J1
STS Pointer
5
B3
C2
Line OH
G1
STS-1 SPE
STS-1 SPE Payload
DS3 Mapped or
7x VTG Mapped
F2
H4
ptr
F3
K3
Z3
VT
VT
VT
VT
VT
VT
VT
Group
Group
Group
Group
Group
Group
Group
Vx
V
T
1
5
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Points to Remember in SONET
• The base layer is the STS-1 SPE
Single pointer to get to the STS-1 SPE (50MB level)
ALL tributary signals multiplex (via Pointer Processing)
to the STS-1 SPE
Each STS-1 has it’s own path overhead
TOH is called Section and Line Overhead
SS bits (in H1) is set to 00
Bellcore (Telcordia) Alarming and GR-820 Performance
Monitoring
Other Nuances:
Path Trace is 64bytes, Orderwire is Mu-Law, Z bytes
not used, No J2, APS is different
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SDH
• Defined by ITU-T (previously CCITT) committees
Base rate (High Order) is 155.520 (STM-1)
Virtual Container 4 (VC-4) = 150.336M used for carrying
tributaries or an E4 signal (or data)
Tributaries (Low Order) used for SDH are:
VC-11 = 1.728M for carrying DS1 (1.544) (rarely used in
AU4)
VC-12 = 2.304M for carrying CEPT (E1)
Also a stuffing option for mapping VC11/1.5M to TU-12
VC-2 = 6.912M Just gaining acceptance (TU-2-Mc) for data
VC-3 = 50.112M (Same as STS-1 SPE) used for E3 AND DS3
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SDH Hierarchy
STM-64
AU-4-64c
VC-4-64c
C-4-64c
9039.872Mb/s
AU-4-16c
VC-4-16c
C-4-16c
2259.968Mb/s
AU-4-4c
VC-4-4c
C-4-4c
564.992Mb/s
AU-4
VC-4
C-4
E4: 139.264Mb/s
C-3
E3: 34.368Mb/s
DS3: 44.736Mb/s
x4
x64
STM-16
x16
x16
x4
STM-4
x4
STM-1
AUG
x3
x3
AU-3
TUG-3
High Order Payloads
Containers of Base Signal
(Low Order Payloads)
TU-3
VC-3
VC-3
x7
x7
STM-n
AUG
AU-n
VC-n
Synchronous Transport Module
x1
TUG-2
Administrative Unit Group: One or
more AU(s)
TU-2
VC-2
C-2
DS2:6.312 Mb/s
TU-12
VC-12
C-12
E1: 2.048Mb/s
TU-11
VC-11
C-11
DS1:1.544Mb/s
x3
Administrative Unit: VC + pointers
Virtual Container: payload + path
overhead
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x4
12
STM-1 Frame with AU-4 Mapping
9 bytes
3
Regenerator
Section OH
1
AU Pointer
5
Multiplex
Section
OH
261 bytes
J1
B3
C2
G1
F2
H4
F3
VC-4 Payload:
C4 or TUG-3 mapped
H1 H1 H1
H2 H2 H2
H3 H3 H3 J1
J1
B3
B3
C2
C2
K3
N1
G1
Higher Order
Path OH
F2
H4
5
bytes
C-3
Payload
ptr
G1
F2
H4
TUG-3
C-3
TUG-2/VC12
Payload
Muxed
Vx
F3
F3
K3
K3
V
N1
N1
C
1
2
Low Order
Path OH
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Points to Remember in SDH
• The base layer is the VC-4 Container
Single pointer to get to the VC-4
ALL Low Order (LO) Signals multiplex (via PP) to the VC-4
Additional pointer to get to VC-3, the STS-1 equivalent: A
FUNDAMENTAL DIFFERENCE between SONET and SDH
TUG-3 is NOT the same as an STS-1
TOH is called Regenerator Section (RS) and Multiplex Section
(MS) Overhead
SS bits (in H1) is set to 01
ITU-T Alarming and ITU-T Performance Monitoring
Other Nuances:
Path Trace (P-API) is 16 or 64 bytes, Orderwire is A-Law, Z
(N1) bytes used for TCM, APS is different
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SONET Vs. SDH
• SONET UPSR = SDH SNCP (Sub-Network Connection
Protection)
WTR is up to 12 minutes in 1 minute increments
“Hold-off” timer for SDH – 0-10S in 100mS increments
• SONET BLSR = SDH MS-SPRing (Multiplex Section – Shared
Protection Ring), SDH does not specify MS-SPRing @ STM-4
(but we allow it)
• SONET APS = SDH MSP (Multiplex Section Protection)
• SONET Mesh/ Virtual Ring = SDH Same as/Extension of SNCP
(and this has been around a while in SDH Networks)
• SONET Path Trace = SDH Path Access Point Identifier (P-API, or
API)
• SONET Alarms: CR, MJ, MN = SDH Alarms PMA (Prompt
Maintenance Activity), DMA (Deferred Maintenance Activity): We
kept the CR/MJ/MN and added the “-PMA/DMA as a suffix
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SONET Vs. SDH (cont…)
• SDH Collects Errored Block Seconds, Errored Second “Ratios”
• SDH is beginning to use Tandem Connection Monitoring –
“Path within a path”
Adds additional Path Trace, BIP, FEBE and RDI to a high or
low-order path
• SONET, STS-SPE (50.112M) is the base-rate payload – SDH, the
base is 155M and the VC-3 (STS equivalent) is a “tributary” to
the VC-4
• It’s not a central office, it’s an “Exchange”
• It’s not a Class 5/ Class 4, it’s a Local Switch and a Transit
Switch
• It’s not a DCS, it’s a DXC
SONET uses 3/3s and 3/1s, SDH uses 4/4s and 4/3/1s
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Terminology Summary
Optical I/O Board
Path Type
SDH
SONET
STM-1
OC-3
STM-4
STM-16
SONET
Not applicable
STS-1
VC4
STS-3c
VC4-4c
STS-12c
VC4-8c
STS-24c
VC4-16c
STS-48c
VC4-64c
STS-192c
OC-12
OC-48
STM-64
OC-192
STM-256
OC-768
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SDH
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Terminology Summary
Protection Type
Overhead Naming
SDH
SONET
MSP
APS/FFP
MS-SPRing
BLSR
SNCP
PPMN/UPSR
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SDH
SONET
RS - Regenerator
Section
Section
MS - Multiplex
Section
Line
HP - High Order
Path
Path
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Terminology Summary
Alarms
SDH
SONET
LOS
LOS
LOF
LOF
RS-TIM
TIM-S
MS-AIS
MS-RDI
MS-DEG
MS-EXC
MS-REI
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SDH
SONET
AU-LOP
LOP-P
AU-AIS
AIS-P
HP-UNEQ
UNEQ-P
HP-TIM
TIM-P
HP-SLM
SLM-P
HP-RDI
RDI-P/RFI-P
HP-DEG
SD-P
HP-EXC
SF-P
HP-REI
REI-P
AIS-L
RDI-L/RFI-L
SD-L
SF-L
REI-L
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Terminology Summary
PM Monitored Types
SDH
SONET
Not defined
CV – Code Violation
EB – Errored Block
Not defined
BBE – Background Block Error
Not defined
ES – Errored second
ES – Errored second
Not defined
SEFS - Severely Errored Framing Seconds
SES - Severely Errored Second
SES - Severely Errored Second
Not defined
FC- Failure Count
UAS - Unavailable Second
UAS - Unavailable Second
BBER - Background Block Errored Ratio
Not defined
ESR – Errored second Ratio
Not defined
SESR - Severely Errored Second Ratio
Not defined
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Terminology Summary
PM Monitored Entities
SDH
SONET
SDH
SONET
Not defined
FC-LNE
Not defined
CV-S
Not defined
FC-LFE
RS-EB
Not defined
MS-UAS-NE
UAS-LNE
RS-BBE
Not defined
MS-UAS-FE
UAS-LFE
RS-ES
ES-S
Not defined
CV-PNE
Not defined
CV-LNE
Not defined
CV-PFE
Not defined
CV-LFE
HP-EB-NE
Not defined
MS-EB-NE
Not defined
HP-EB-FE
Not defined
MS-EB-FE
Not defined
HP-BBE-NE
Not defined
MS-BBE-NE
Not defined
HP-BBE-FE
Not defined
MS-BBE-FE
Not defined
HP-ES-NE
ES-PNE
MS-ES-NE
ES-LNE
HP-ES-FE
ES-PFE
MS-ES-FE
ES-LFE
HP-SES-NE
SES-PNE
HP-SES-FE
SES-PFE
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Terminology Summary
PM Monitored Entities (Cont.)
SDH
SONET
Not defined
FC-PNE
Not defined
FC-PFE
HP-UAS-NE
UAS-PNE
HP-UAS-FE
UAS-PFE
HP-BBER-NE
Not defined
HP-BBER-FE
Not defined
HP-ESR-NE
Not defined
HP-ESR-FE
Not defined
HP-SESR-NE
Not defined
HP-SESR-FE
Not defined
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Cisco Systems
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