Synchronous Optical NETwork - CUNY

fishecologistMobile - Wireless

Dec 12, 2013 (3 years and 11 months ago)

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SONET

What is SONET?


S
ynchronous
O
ptical
Net
work

standard







Defines a digital hierarchy of synchronous signals


Maps asynchronous signals (DS1, DS3) to synchronous format


Defines electrical and optical connections between equipment


Allows for interconnection of different vendors’ equipment


Provides overhead channels for interoffice OAM&P

SONET

Network

Element

SONET

Network

Element

Digital

Tributaries

Digital

Tributaries

Asynchronous Vs
Synchronous



Assume Maximum Clock Rate



Bit
-
Stuff As Required

DS
-
M

DS
-
(M+1)

Asynchronous


(aka Plesiochronous)

o

o

o



Use Network Clock Rate



Use Pointers To Find Payload

SONET

VT1.5 Or

STS
-
M

STS
-
N

(M < N)

o

o

o

Digital Signal Hierarchies

Most Common Rates

Asynchronous

SONET

VT1.5

(1.7 Mb/s)

STS
-
3

(156 Mb/s)

STS
-
12

(622 Mb/s)

STS
-
48

(2500 Mb/s)

28

84

336

1344

Capacity

(DS
-
1 Equiv)

DS
-
1

(1.544 Mb/s)

STS
-
1

(52 Mb/s)

[Non
-
Standardized]

STM
-
1

STM
-
4

STM
-
16

SDH

DS
-
0

(64 Kb/s)

VC
-
11

VC
-
3

DS: Digital Signal

SONET: Synchronous Optical NETwork (US)

SDH: Synchronous Digital Hierarchy (ITU)

STS: Synchronous Transport Signal

STM: Synchronous Transfer Mode

VC: Virtual Container

VT: Virtual Tributary

DS
-
3

(45 Mb/s)

SONET Rates

STS
-
1

OC
-
1


51.840

STS
-
3

OC
-
3

155.520

STS
-
12

OC
-
12

622.080

STS
-
48

OC
-
48

2,488.320

STS
-
192 OC
-
192 9,953.280

Level

Optical

Designation

Bit Rate

(Mb/s)

STS

=

SYNCHRONOUS TRANSPORT SIGNAL

OC

=

OPTICAL CARRIER


(“..result of a direct optical conversions of the STS after


synchronous scrambling”
-

ANSI)

SONET Network Layers

DS3

etc

DS3

etc

Path



Map Services & POH Into SPE



Path Protection/Restoration



Other Path OA&M Functions

Line



Combine SPE & LOH



Sync & Mux For Path Layer



Line Protection/Restoration



Other Line OA&M Functions

Section



Add SOH & Create STS Signal



Framing, Scrambling



Section OA&M Functions

Physical

(Photonic
)



E/O Conversion



Line Code



Physical Signal

[No additional overhead]

MUX

LTE

Regen

MUX

LTE

LTE

Regen

Services

DS3, DS1, etc

SONET ADM

Path

Line

Line

Section

Section

Section

Section

Case Study:

Two Path Layer Processors are
Exchanging DS3s

SONET

Terminal

STS
-
1

OC
-
1

SONET

Terminal

STS
-
1

OC
-
1

Regen

Mux

Mux

Section

Section

Line

Path

PTE

PTE

LTE

LTE

Map services & Path Over
-

Head into SPE

Map SPE & Line Over
-

Head into STS
-
N

Map STS
-
N & Section

Overhead into “Pulses”

Optical Conversion

Terminal

Terminal

Regen

Path

Line

Section

Photonic

Functional Description of SONET Layers

OH: Overhead

Path Layer

Line Layer

Section

Layer

Photonic

Layer

Information

Payload

Path

OH

Line

OH

Section

OH

E/O Conversion

Transmission over OC
-
N

Function

Payload Mapping

Error Monitoring



Synchronization

Multiplexing

Error Monitoring

Line Maintenance

Protection Switch

Order Wire


Framing

Scrambling

Error Monitoring

Section Maintenance

Orderwire



E/O Conversion

Pulse Shaping

Power Level

Wavelenght

SONET STS
-
1 Frame
Structure

Synchronous

Payload

Envelope

(SPE)

T

O

H

Ptr

87

Bytes

3

Bytes

SPE



87 Columns

P

O

H

9

Rows

87

Bytes

3

Bytes

t

t

F

I

x

e

d


S

t

u

f

f

F

I

x

e

d


S

t

u

f

f

Efficiencies

Mb/sec

% STS1

STS1

51.84

100%

SPE (87 col)

50.11


96.67%

SPE (84 col)

48.38


93.33%

DS3

43.23


86.30%

672 DS0’s

43.00


82.96%


P

O

H

STS
-
1 Payloads

1

VT1.5

(1.7 Mb/sec)

DS
-
1

(1.544 Mb/sec)

27

3 Columns

4 columns

VT Group

(12 Columns)

x 4

VT2

(2.3 Mb/sec)

6 columns

VT3

(3.5 Mb/sec)

12 columns

VT4

(6.9 Mb/sec)

VT Group

(12 Columns)

VT Group

(12 Columns)

VT Group

(12 Columns)

x 3

x 2

SPE

(84 Usable


Columns)

Sub

STS
-
1

Mappings

90 Total Columns

P

O

H

Ctl

&

Stuff

Information

S

t

u

f

f

Ctl

&

Stuff

Information

S

t

u

f

f

Ctl

&

Stuff

Information

3

25

28 Columns

3

25

28 Columns

3

25

28 Columns

DS
-
3

STS
-
1 Overhead Structure

Section

OH

A1

A2

J0

B1

E1

F1

D1

D2

D3

H1

H2

H3

D4

D5

D6

D7

D8

D9

D10

D11

D12

Z1

Z2

E2

B2

K1

K2

Framing

STS1 ID

BIP
-
8

(previous frame)

Orderwire

(64 kb/sec)

User Channel

DataComm
( 192 kb/sec)

Pointer

Action

BIP
-
8

(previous LOH+SPE)

Prot

Switching

DataCom

(576 kb/sec)

NE

Sync

FEBE

Orderwire

(64 kb/sec)

Line

OH

Transport Overhead

(3 Columns)

J1

B3

C2

G1

F2

H4

Z3

Z4

Z5

Path Overhead

(1 Column)

Path Trace

(multi
-
frame)

BIP
-
8

Signal Label

Path Status

User Channel

Indicator

(multi
-
frame)

Growth

Growth

0
-

2 Bytes

For Sync

Identifies

Source of Sync

Eg, CLLI Code

BIP
-
8
: Bit Interleaved Parity
-
8 (each bit set to give even parity over same
-
positioned bits)

SPE Type:



DS3



ATM



VT
-
Structured



Unequipped



Etc



Path FEBE
(4 bits)



RDI
-
P
(4 bits)
showing



AIS
-
P



LOP
-
P

SPE Type
-
Dependent

Growth

FEBE:
Far End Block Error
(Count of BIP
-
8 Errors On Reverse Channel)

AIS
-
L

STS
-
N And STS
-
Nc

(N = 3, 12, 48)



STS
-
N



Formed By Byte
-
Interleaving N STS
-
N Signals



3N Columns of Transport Overhead



Frame Aligned



Redundant Fields Not Used
-

eg APS, Datacomm



N Distinct Payloads (87N Bytes)



NOT Frame Aligned



N Columns Of Path Overhead
-

All Used



2N Columns Of Fixed Stuff Bytes



84N Columns Of Information




STS
-
Nc



3N Columns of Transport Overhead



Frame Aligned



Redundant Fields Not Used
-

eg APS, Datacomm



Single Payload



1 Column Of Path Overhead



3/N
-

1 Columns Of Fixed Stuff Bytes



87N
-

3/N Columns Of Information

STS
-
1, STS
-
3, & STS
-
3c

TOH

P

O

H

125
m

sec

TOH

P

O

H

125
m

sec

TOH

P

O

H

125
m

sec

P

O

H

P

O

H

P

O

H

TOH

125
m

sec

P

O

H

TOH

125
m

sec

STS
-
1

STS
-
3c

STS
-
3

Layering Application Bellcore Approach

A

B

C

D

E

Trunks

(DS1 = 24 Trunks)

4E

4E

4E

4E

A

B

C

D

DS3 or OC3

A

D

E

OC
-
48

A

B

C

D

E

Switched

Cross
-

Connect

Multiplex

Photonic

LAYER

B

C

DCS

DCS

DCS

DCS

DCS

ADM

ADM

ADM

ADM

ADM

ADM

ADM

DS1

DS3/OC3

OC48

Customer

Service Requests

Pt
-
Pt Traffic

(Erlangs)

DS1

Private Line

DS3/OC3/OC12

Private Line

[OC48

Private Line]

Generic SONET Network
Elements

o

o

o

o

o

o

STS
-
N

Ports

STS
-
N

Ports

STS
-
M

Fabric

(M<N)

o

o

o

STS
-
M

Ports

M:N

Digital Cross
-
Connect System

(DCS)

STS
-
M

Fabric

(M<N)

o

o

o

STS
-
M

Ports

M:N

Add/Drop

Multiplexer

(ADM)

STS
-
N

o

o

o

STS
-
M

Ports

W

E

STS
-
N

STS
-
N

M:N

Multiplexer

(aka “End Terminal”)

SONET Configurations

Key SONET Configurations

48 S

48 P

Point

To

Point



Compatible With OLS



2 Nodes Per System



All T3’s Use DACS III



1x1 Protection Switching



Compatible With OLS



2 To 16 Nodes



Add/Drop Multiplexing


(“Tributary Add/Drop”)
-


Only DS3’s Changing Routes Or


Terminating Use DACS III



1x1 Protection Switching

48 S

48 P

DACS

III

DCS

III

ADM

ADM

ADM

ADM

ADM

ADM

48 S

48 P

All DS3’s

All DS3’s

48 S

48 P

ET: End Terminal

ADM: Add/Drop Multiplexer

ET

ET

ET

ET

ET

ET

ET

ET

Key SONET Configurations

Linear Office Sequences

ET

III

Point

To

Point

Linear

Add/Drop

(“Open Ring”)

o o o

III

ET

ET

III

ET

ET

III

ET

III

ET

ET

ET

III

N Offices



2 End Offices



N
-
2 Interior Offices

ET

III

III

ET

ADM

ADM

ET

ADM

ADM

o o o

Key SONET Configurations

III

III

III

III

III

Point

To

Point

Closed

Ring

S

P



Compatible With OLS



2 Nodes Per System



1x1 Protection Switching,



DACS III
-

Based Restoration



Compatible With OLS



2 To 16 Nodes
-

End Terminals At Ends,


ADM’s Elsewhere



Add/Drop Multiplexing


(“Tributary Add/Drop”)



1x1 Protection Switching,



DACS III
-
Based Restoration At Ends


& Add/Drop Points Only



Compatible With OLS



2 To 16 Nodes



Add/Drop Multiplexing


(“Tributary Add/Drop”)



1x1 Protection Switching



Ring Loopback Protection Switching



Must Be Of Uniform Size Around


Entire Loop

DACS

III

ET

ET

ET

ET

“MESH”

“RING”

Linear

Add/Drop

(“Open Ring”)

DACS

III

ADM

ET

ET

DACS

III

ADM

ADM

ADM

ADM

ADM

ET: End Terminal

ADM: Add/Drop Multiplexer

III

S

P

S

P

S

P

S

P

S

P

S

P

S

P

S

P

SONET Network Management

SONET Ring APS (
Automatic Protection Switching
)


Uni
-
directional Vs. Bi
-
directional Rings


Two
-
Fiber Vs. Four Fiber Rings


Ring Switching Vs. Span Switching

Applications of:



Bi
-
directional Line Switched Ring (BLSR)



Uni
-
directional Path Switched Ring (UPSR)

Definition of a Ring

A Ring is a collection of nodes (NE1, NE2, ….)


forming a closed loop.

Each node is connected to two adjacent nodes

via

a duplex communications facility.



A SONET Ring will provide:



Redundant Bandwidth



Redundant Network Equipment



or both.

Ring Classification


A Unidirectional Line Switched Ring (ULSR)


A Bidirectional Line Switched Ring (BLSR)


A Unidirectional Path Switched Ring (UPSR)


A Bidirectional Path Switched Ring (BPSR)


Any of the above type can be a two
-
fiber or a four fiber ring.

Therefore, for all practical applications, SONET/SDH standards

provide
eight types of ring for network node interconnections.

Unidirectional Vs. Bidirectional Rings

C

B

A

D

A


B : 1


B


A : 2

3

4

1

2

3

4

5

6

7

8

A
-

Unidirectional Ring

C

B

A

D

A


B : 1


B


A : 5

1

2

3

4

5

6

7

8

B
-

Bidirectional Ring

Two
-
Fiber Vs. Four
-
Fiber Rings

C

B

A

D

A

B

Working 1


Protection 2

Working 2


Protection 1

A
-

Two
-
Fiber Ring/Span

C

B

A

D

A

B

Working 1


Protection 1

Working 2



Protection 2

B
-

Four
-
Fiber Ring/Span

Ring Switching 2
-
Fiber Ring

C

B

A

D

Failure

Route before PS (Protection Switching)

A: Ring Switching: Two
-
fiber ring

50%

50%

50%
-

original

+

50%
-

additional

50%
-

original

+

50%
-

additional

Ring Switching 4
-
Fiber Ring

B: Ring Switching: Four
-
fiber ring

C

B

A

D

Route before PS

Span Switching
-

4
-
fiber Rings only

C

B

A

D

Route before PS

B: Ring Switching: Four
-
fiber ring

A

B

Route before PS

Route after PS

Bi
-
directional Line Switched Ring

No Failures

C

B

A

F

S

S

S

S

S

P

P

P

P

P

D

E

S

P

Original Circuit

A

B

C

C

B

A

Bidirectional

Traffic

Unidirectional

Traffic

SONET Add
-
Drop Multiplexer (ADM)

Lucent FT
-
2000 LCT Example

)

OC
-
48



OC
-
48



OC
-
48



OC
-
48



STS
-
3

Fabric

STS
-
3 Terminations (<= 4x16 = 64)

STS
-
3

STS
-
3

STS
-
1/DS3

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

SERVICE

WEST

PROTECTION

WEST

SERVICE

EAST

PROTECTION

EAST

Bi
-
directional Line Switched Ring

Span Switch

S

F

C

B

S

S

S

S

P

P

P

P

P

D

E

S

P

X

A

Original Circuit

Protection Switch

SONET
ADM

Automatic Protection
Switching

Lucent FT
-
2000 LCT Example

)

OC
-
48



OC
-
48



OC
-
48



OC
-
48



STS
-
3

Fabric

(60 ms

switch

time)

STS
-
3 Terminations (<= 4x16 = 64)

STS
-
3

STS
-
3

STS
-
1/DS3

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

SERVICE

WEST

PROTECTION

WEST

SERVICE

EAST

PROTECTION

EAST

Bi
-
directional Line Switched Ring

Ring Switch

S

E

C

B

A

F

S

S

S

S

P

P

P

P

P

D

S

P

Original
Circuit

Ring Switch

X

SONET ADM Ring Protection Switching

Lucent FT
-
2000 LCT Example

)

OC
-
48



OC
-
48



OC
-
48



OC
-
48



STS
-
3

Fabric

(60 ms

switch

time)

STS
-
3 Terminations (<= 4x16 = 64)

STS
-
3

STS
-
3

STS
-
1/DS3

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

OC
-
48

Terminating

Equipment

SERVICE

WEST

PROTECTION

WEST

SERVICE

EAST

PROTECTION

EAST

Ring Restoration Protocol

Reference: GR
-
1230
-
CORE

Issue 1, 12/93

1
-
4

5
-
8

Bridge Request Priority

Destination Node ID

K1

K2

Sourcing Node ID

1
-
4

5

S


/


L

Completed Action

1111 LP
-
S Protection Lockout (span) or


Signal Fail Of Protection(span)

1110 FS
-
S Forced Switch (Span)

1101 FS
-
R FS (Ring)

1100 SF
-
S Signal Failure (Span)

1011 SF
-
R Signal Failure (Ring)

1010 SD
-
P Signal Degrade (Protection)

1001 SD
-
S Signal Degrade (Span)

1000 SD
-
R Signal Degrade (Ring)

0111 MS
-
S Manual Switch (Span)

0110 MS
-
R Manual Switch (Ring)

0101 WTR Wait To Restore

0100 EX
-
S Exerciser (Span)

0011 EX
-
R Exerciser (Ring)

0010 RR
-
S Reverse Request (Span)

0001 RR
-
R Reverse Request (Ring)

0000 NR No Request

0 Short Path

1 Long Path

111 Line AIS

110 Line RDI


:

010 Bridged and Switched)

001 Bridged

000 Idle

AIS = Alarm Indication Signal

FS = Forced Switch

RDI = Remote Defect Indication


SF = Signal Failure

SD = Signal Degrade

FS = Forced Switch

4 bits

4 bits

Route Failure In Ring

F

A

D

E

P

Ring

Bridge

& Switch

X

X

X

S

P

X

Ring

Bridge

& Switch

SF
-
R/E

F/L/Br&Sw

X

SF
-
R/F

E/L/Br&Sw

Detect Failure

on Working & Protection

Detect Failure

on Working & Protection

SF
-
R/E

F/L/Idle

SF
-
R/F

E/L/Idle

SF
-
R/E

F/L/Idle

SF
-
R/F

E/L/Idle

1

1

2

2

Bi
-
directional Line Switched Ring

Ring Switch
-

Node Failure

F

C

B

A

S

S

S

S

S

P

P

P

P

P

D

S

P

E

x

Original Circuit

Ring Switch

Bi
-
directional Line Switched Ring

No Failures

C

B

A

F

S

S

S

S

S

P

P

P

P

P

D

E

S

P

Original Circuits (Both Slot 2)

Bi
-
directional Line Switched Ring

Need For Squelching

C

B

A

F

S

S

S

S

P

P

P

P

P

D

E

S

P

Original Circuits (Both Slot 2)

x



Requires Sharing


of State Information



Significant Software


Complexity

Bi
-
directional Line Switched Ring

Double Ring Failure
(No Recovery)

Original Circuit

Ring Switch

C

B

A

F

S

S

S

S

S

P

P

P

P

P

D

E

S

P

X

X

SONET Rings will fail
--


The question is “When?”


Initial estimates of DWDM hardware show that it is 8 times
more reliable than WDM equipment.


POEs not included


Ring reliability is dependent upon ring mileage.


Ring sizes vary from 200 miles to 2800 miles.


Ring Failures:


Given 100, 1000
-
mile perimeter rings:


Current optimistic estimation is 1 network ring failure every 5 yrs.


PCIs not included


Most probable cause of a complete ring failure is an equipment failure
and a fiber cut.


Physical diversity violations in some rings (
single
-
pt
-
of
-
failure).

Restoration Alternatives

Target Failure Modes

Route

(Ring)

1 Fiber

(Ring or

Pt
-
Pt)

Span Protection Switch


Ring Protection Switch

Nominal

Response

Time

Yes


No

No


Yes

50 ms


100 ms

No


No

No


No

No


No

Total

Ring

Ring

Interconnect

Node

Access/Egress

Node or ADM

Multiple

Rings

No


No


Ring

Node

No


Yes

Route

(Pt
-
Pt)

No


No

Ring Interworking

Interconnect Problem
(No Recovery)


A

C

B

D

Z

E

D

S

S

S

S

S

P

P

P

P

P

Office X

S

S

S

S

S

P

P

P

P

P

Ring

1

Ring

2

X

Original Circuit

Failure

Dual Ring Interworking

(Unidirectional A => Z Circuit)

No Failure


A

C

B

Z

E

D

S

S

S

S

S

P

P

P

P

P

Office X

Office Y

S

S

S

S

S

P

P

P

P

P


SS

Ring

1

Ring

2

v

v

v

v

v

v

v

Original Circuit

Secondary (Inactive)

v

v

Dual Ring Interworking

(Unidirectional A => Z Circuit)

ADM Failure


A

C

B

Z

E

D

S

S

S

S

S

P

P

P

P

P

Office X

Office Y

S

S

S

S

S

P

P

P

P

P


SS

Ring

1

Ring

2

v

v

v

v

X

Original Circuit

Secondary Circuit


Ring Switch

Dual Ring Interworking

(Unidirectional A => Z Circuit)

Office Or Double ADM Failure


E

v


A

C

B


Z

D

S

S

S

S

S

P

P

P

P

P

Office X

Office Y

S

S

S

S

S

P

P

P

P

P

Ring

1

Ring

2


SS

X

X

Original Circuit

Secondary Circuit


Ring Switch

DRI Capacity Impact

All Transit Traffic Example

X

Y

24

DS
-
3s

Z

X

Y

Z

48

DS3s

48

DS3s

48

DS3s

(a) No DRI

(b) With DRI (Secondary Channel On Service Capacity)

24

DS3s

24

DS3s

Restoration Alternatives

* If restoration capacity is available

** Can help in a limited number of specific failure situations

Target Failure Modes

Route

(Ring)

1 Fiber

(Ring or

Pt
-
Pt)

Span Protection Switch


Ring Protection Switch


DRI

Nominal

Response

Time

Yes


No


No

No


Yes


No

50 ms


100 ms


100 ms

No


No


Yes**

No


No


No

No


No


Yes

Total

Ring

Ring

Interconnect

Node

Access/Egress

Node or ADM

Multiple

Rings

No


No


No

Ring

Node

No


Yes


No

Route

(Pt
-
Pt)

No


No


No

Ring/Mesh Example
-

1

40 T3

40 T3

40

T3

40

T3

Balanced

Demands

1 OC48 (1x1)

1 OC48 (1x1)

1

OC48

(1x1)

1

OC48

(1x1)

1 OC48 (1x1)

1 OC48 (1x1)

1

OC48

(1x1)

1

OC48

(1x1)

ADM/DWDM


$2.0M $2.0M $2.0M

Protection Access


0 0.8 0.4

TOTAL


$2.0 $2.8 $2.4

Ring/Mesh Ratio


0.72 0.83


RING Restn Restn


100% PMO

MESH

Ring

Mesh

ADM

DACS III

ADM

DACS III

Svce

Svce

Prot

Note: DWDM Costs Prorated Per OC
-
48.


No OA’s.

Ring/Mesh Example
-

1

40 T3

40 T3

40

T3

40

T3

60 T3

40 T3

40

T3

40

T3

Balanced

Demands

Unbalanced

Demands

1 OC48 (1x1)

2 OC48 (1x1)

1

OC48

(1x1)

1

OC48

(1x1)

1 OC48 (1x1)

1 OC48 (1x1)

1

OC48

(1x1)

1

OC48

(1x1)

2 OC48 (1x1)

2 OC48 (1x1)

2

OC48

(1x1)

2

OC48

(1x1)

1 OC48 (1x1)

1 OC48 (1x1)

1

OC48

(1x1)

1

OC48

(1x1)

ADM/DWDM


$2.0M $2.0M $2.0M

Protection Access


0 0.8 0.4

TOTAL


$2.0 $2.8 $2.4

Ring/Mesh Ratio


0.72 0.83

ADM/DWDM

$4.0M $2.9M $2.9M

Protection Access


0 0.9 0.6

TOTAL


$4.0 $3.8 $3.5

Ring/Mesh Ratio


1.06 1.15


RING Restn Restn


100% PMO

MESH


RING Restn Restn


100% PMO

MESH

Ring

Mesh

Note: DWDM Costs Prorated Per OC
-
48.


No OA’s.

Ring/Mesh Example
-

2

40 T3

40

T3

40 T3

40

T3

40

T3

40

T3

40 T3

Ring

Mesh

One

Extra

1x1 OC
-
48

40

T3

40

T3

40

T3

40

T3

40

T3

40

T3

40

T3

40

T3

40

T3

40

T3

40 T3

40 T3

40 T3

Ring/Mesh Example
-

3

Ring

Mesh

New

Route

Hybrid Network Concept



Both Ring & Mesh Restoration Architectures Would Be Used



Each OC
-
48 Would Be Either Ring Or Mesh Protected, But Not Both



DWDMU Network Would Be Shared



An Office Would Have A Mix Of Ring & Mesh OC
-
48’s, Depending On
Service Mix & Economics

Sample SONET Architecture

P

Circuit

DCS

DCS

48 S

48 S

48 P

48 P

48 P

48 P

48 S

48 S

ADM

ADM

DCS

P

S

Circuit

DCS

DCS

S

P

S

ADM

ADM

DCS

Light

Terminating

equipment

Restoration of DS
-
3 Services


DS
-
3s services can be routed on all rings, all mesh, or
hybrid ring/mesh.


Ring portion of DS
-
3:


Restored by self
-
healing ring for multiple electrical or
single optical/fiber failures, including fiber cuts.


Backed up using DCS for multiple failure scenarios.
Restoral is semi
-
manual and expected to take at least 20
min.


Mesh portion of DS
-
3:


Restored via some “restoration platform”.


Future restoration via the SONET DCS.

Sample T3 Architecture

T3

ADM

DCS

LGX

48 S

48 P

48 P

48 P

48 S

48 S

48 S

48 P

ADM

ADM

ADM

DCS

DCS

ADM

P

S

LGX

DCS

P

S

P

S

T3

Normal Service Path

Ring Restoration Path

Restoration

DCS: Digital Cross Connect System

Sample SONET Architecture

P

Circuit

DCS

DCS

48 S

48 S

48 P

48 P

48 P

48 P

48 S

48 S

ADM

ADM

DCS

P

S

Circuit

DCS

DCS

S

P

S

Light
Terminating
Equipment

ADM

ADM

DCS

P

Circuit

DCS

DCS

48 S

48 S

48 P

48 P

48 P

48 P

48 S

48 S

ADM

ADM

DCS

P

S

Circuit

DCS

DCS

S

P

S

Light
Terminating

ADM

ADM

DCS

P

Circuit

DCS

DCS

48 S

48 S

48 P

48 P

48 P

48 P

48 S

48 S

ADM

ADM

DCS

P

S

Circuit

DCS

DCS

S

P

S

ADM

ADM

DCS

Other Types Of SONET Self
-
Healing Rings

(2
-
Fiber Unidirectional Line
-
Switched Ring)

ADM

A

ADM

ADM

Z

ADM

Notes:
Each Link Is Just 1 (1
-
Way) Fiber


Transmission Directions Routed Differently

Service

Service

Service

Service

Protection

Protection

Protection

Protection

A=>Z

Z=>A

Z=>A

A=>Z

A=>Z

Z=>A

Other Types Of SONET Self
-
Healing Rings

(2
-
Fiber Unidirectional Line
-
Switched Ring)

ADM

A

ADM

ADM

Z

ADM

Service

Service

Service

Service

Protection

Protection

Protection

Protection

Z=>A

A=>Z

Z=>A

A=>Z

Z=>A

A=>Z

Other Types Of SONET Self
-
Healing Rings

(2
-
Fiber Bi
-
directional Line
-
Switched Ring)

ADM

A

ADM

ADM

Z

ADM

Note:
Each Link Uses 1 (1
-
way) Fiber


Capacity On Each Fiber Divided Equally Between Service & Protection


(2 “Logical Fibers”)

Service/Protection

Service/Protection

Service/Protection

Service/Protection

Service/Protection

Service/Protection

Service/Protection

Service/Protection