78728747 77328883 alc sdh basics and alcatel sdh system training presentation 46 slide

7/22/2019 78728747 77328883 ALC SDH Basics and Alcatel SDH System Training Presentation 46 Slide

1/46

SDH Presentation

-SDH Basics

-Alcatel SDH Systems

-Alcatel 1662SMC Introduction

-SDH Link No.17


2/46

SDH Basics

What are SDH & PDH ?

Advantages of SDH over PDH.

SDH Data rates.

SDH Multiplexing Structure.

SDH Basic Frame Structure.


3/46

SYNCHRONOUS DIGITAL HIERARCHY


4/46

SDH Basics What are SDH & PDH ?

SDH stands for Synchronous Digital Hiararchy.In SDH each and every signal is synchronized exactly to the

single (container) defined for that particular signal ( like C11,C12,etc).The techniques like bit stuffing and

bit justification are adopted in SDH to achieve the synchronization.

The signal used for SDH transmission is known as Synchronous Transport Module (STM).

The various STM rates are illustrated below

STM-1 (155.52 Mbps)

STM-4 (622.08 Mbps)

STM-16 (2488.32 Mbps)STM-64 (9953.28 Mbps)

STM-256 (39813.12 Mbps)

SDH

MUX

SDH

MUX

SDH

MUX

SDH

MUX

STM-1

STM-1

STM-1

STM-1 STM- 4

STM- 4

STM- 4

STM- 4

STM- 16

STM- 16

STM- 16

STM- 16

STM- 64

STM- 64

STM- 64

STM- 64

STM- 256


5/46

PLESIOCHRONOUS DIGITAL

HIERARCHY


6/46

Plesio means = similar

Chronous means= Timing

Plesiochronous almostsynchronous,

becausethe digitalsignalsbeingmultiplexed togetherare not

at quitethesame frequency

PDH (Plesiochronous Digital Hierarchy)


7/46

SDH Basics What are SDH & PDH ? (continues)

PDH stands for Pleisynchronuous Digital Hiararchy.The PDH contains the signals having similar data

rate signals (like E1,E 2,E3,T1,T2,etc.) but with slight timing differences as shown below.

E1 2.048 Mbps [32 x 64 kbps (DS0)]

E2 8.448 Mbps [4 x E1]

E3 34.368 Mbps [4 x E2]

E4 139.264 Mbps [4 x E3]

PDH

MUX

PDH

MUX

PDH

MUX

E1(2.047990 Mbps)

E1(2.048001 Mbps)

E1(2.047992 Mbps)

E1(2.048000 Mps)

E2(8.447997 Mbps)

E3(34.367998Mbps)

E3(34.367990Mbps)

E3(34.368000Mbps)

E3(34.367989Mbps)

E2(8.447991 Mbps)

E2(8.448000 Mbps)

E2(8.447989 Mbps) E4(139.264000Mbps)


8/46

SDH Basics Advantages of SDH over PDH

High Transmission Rates:

The highest data rate that can be achieved with PDH technologies is 140 mbps, whereas the transmissionrates up to 10Gbps (STM-64) can be achieved with SDH technology.

Easy Add & Drop Functionality:

Compared to the older PDH system, low bit rate channels can be easily extracted from and inserted into thehigh-speed bit streams in SDH. It is now no longer necessary to apply the complex and costly procedure ofdemultiplexing then remultiplexing the plesiosynchronous structure.

High Availability and Capacity matching:With SDH, network providers can react quickly and easily to the requirements of their customers. Forexample, leased lines can be switched in a matter of minutes. The network provider can use standardizednetwork elements (NE) that can be controlled and monitored from a central location via atelecommunications management network (TMN) system.

Reliability:Modern SDH networks include various automatic back-up circuit and repair mechanisms (like Automatic ProtectionSwitching (APS) and Equipment Protection Switching (EPS) which are designed to cope with system faults and aremonitored by management. As a result, failure of a link or an NE does not lead to failure of the entire network.

Integrated Services:

SDH is the ideal platform for a wide range of services including POTS, ISDN,mobile radio, and datacommunications (LAN, WAN, etc.). It is also able to handle more recent services such as video on demandand digital video broadcasting via ATM.


9/46

Changing from one hierarchical level to another

requires additional equipment.

For Add/drop of individual channels from the higher

order stream we have to disassemble / reassemble it

Redirection (cross-connection) of channels must bedone by hand on DDFs.

Administrative connections require separate

equipment to support Supervision, EOW and

protection switching.

Compatibility of transmission and administrative

signals between different vendor may give trouble.

Disadvantages of PDH


10/46

SDH Basics

SDH Data rates:

STM-0 (51.84 Mbps)

STM-1 (155.52 Mbps)

STM-4 (622.08 Mbps)

STM-16 (2488.32 Mbps)

STM-64 (9953.28 Mbps)

STM-256 (39813.12 Mbps)

Note: The STM-0 is not widely used in the telecom network except for some Microwave

Links.


11/46

SDH Basics

SDH Multiplexing Structure:

C11VC11TU-11

C12VC12TU-12

C2VC2TU-2TUG-2

C3VC3AU-3STM-0

TU-3 VC3

C4

TUG-3

VC4AU-4AUGSTM-N

T-1(1.544Mbps)

Or

ATM(1.6Mbps)

E-1(2.048Mbps)

OrATM(2.144Mbps)

T-2(6.312Mbps)

Or

ATM(6.874Mbps)

T-3(44.736Mbps)

Or

E-3(34.368Mbps)

Or

ATM(48.384Mbps)

E-4(139.264Mbps)

Or

ATM(149.760Mbps)

x1xN

x4

x3

x1

x7

x3

Containers

Virtual Containers (Containers + POH)

Tributary Units/Administrative Units(Virtual Containers + Pointers)

Tributary Unit Groups/Administrative Unit Groups(Multiplexed structures of lower signals)

Alignment

Multiplexing


12/46

SDH Multiplexing Structure:

KLM DETAILS

K-TUG 3

L-TUG 2

M-TU 12

FirstKLM combinationis 1 1 1

LastKLM combinationis 3 7 3

E1 = 32 bytes/frame

C12 = 34 bytes/frame (E1 +2 stuffed bytes)

VC12 = 35 bytes/frame (C12 + 1 POH byte )

TU12 = 36 bytes/frame (VC12 +1 pointer byte) M

So, one TU12 occupies 4 columns(36 bytes) in an STM1 frame

TUG-2 = 3 X TU12 = 12 columns /frame L

TUG-3 = 7 X TUG-2 = 86 columns /frame K

(7 X 12 + 2 stuffed columns are added)

VC4 = 3 X TUG-3 = 261 columns /frame

(3 X TUG-3 + 2 stuffed columns + 1 POH)

STM1 = VC4 + SOH = 261+ 9 = 270 columns /frame.

Mappingof 63 E1sinto STM1


13/46

1.ContainerCn, where C=Container,n=Indexofthecontainer(n=11,12,2,3,4)

Therateofthecontainerdependsonthesignal whichistransported.

2.VirtualcontainerVCn,Itismadeupof Cnand Poh

Vcn=Cn+Poh,wherePohispathoverhead

Pathoverhead containPayload content

3.Tributaryunit TUn=VCn+PTR n=11,12,2,3 loweroderVCn

WherePointerisanaddittionalrateused tolocateits Vcn withinthe TU

4.Tributaryunit Group TUG-k=m*TU-n, where k=2,3 n=11,12,2,3

TUG ,the Tug-2/Tug-3 ca

nconsistofsevera

ltypesofca

pa

citypa

yloa

ds witdifferentsizes.

5.Adminitrative Unit(AU),itismadeupofhigherorderVCn(n=3,4)and apoint

AUn=VCn+PTR n=3,4

AUG=1*AU-4 or3*AU-3


14/46

SDH Basics SDH Basic Frame Structure (STM-1):

Each cell represents a single byte indicating a 64 kbps channel.

RSOH :- Regenerator Section Overhead (27 bytes )

MSOH : Multiplexer Section Overhead (45 bytes)Total Section Overhead (SOH) : RSOH + MSOH

AU-4 Pointer :- 9 bytes

Payload :- 261 x 9 = 2349 bytes

STM -1 Data rate = (270 x 9) bytes

= 2430 bytes

= 2430 x 64 kbps

= 155520 kbps = 155.52 Mbps

RSOH

(3 x 9 Cells)

PAYLOAD (261 x 9 Cells)AU-4 POINTER

MSOH

(4 x 9 Cells)

1

1

9 10

3

4

5

9

270

270 Colomns

9 Rows


15/46

SDH Basics SDH Basic Frame Structure (STM-1) (Continues.):

Section Overhead (SOH )

X Bytes Reserved for national use.

* - Media Dependant Bytes

A1 A1 A1 A2 A2 A2 J0 X X

B1 * * E1 * F1

D1 * * D2 * D3

AU-4 Pointer

B2 B2 B2 K1 K2

D4 D5 D6

D7 D8 D9

D10 D11 D12

S1 M1 E2 X X


16/46

SDH Basics SDH Basic Frame Structure (STM-1) (Continues.):

Overhead Bytes Functions

Overhead Byte Functions

A1,A2 Frame Alignment

B1,B2 Quality Monitoring,paritybytes

D1,D2,D3 Qecc Network Management

D4,..,D12 Qecc Network Management

E1,E2 Voice Connections

F1 Maintenance

J0 Trace Identifier

K1,K2 AutomaticProtection Switching (APS) Control

S1 Clock Quality Indicator

M1 Transmission ErrorAcknowledgement


17/46

Alcatel SDH Systems

Alcatel SDH Systems

1662SMC 1642 1660SM

Version 2(R2)Version 1(R1)Version 5(R5)Version 4(R4)

Supports

Upto STM-4

Supports

Upto STM-16Supports

Upto STM-16

Supports

Upto STM-64

Supports

Upto STM-1


18/46

Alcatel 1662 SMC Introduction

Features

Shelf View

Commonly used cards

Technical Specifications


19/46

Features: It complies with the Synchronous Digital Hierarchy (SDH) defined in ITU-T

Recommendation G.707.

Compatible with existing plesiochronous systems as well as with the installed SDH networks,

The 1662SMC is transmission equipment operating at 155.520 Mbit/s (STM-1) , 622.080Mbit/s (STM-4) and 2488.320 Mbit/s(STM-16).

It can be configured as a Multiple Line Terminal Multiplexers or as a Add/Drop Multiplexersor as a Mini local cross-connect for applications in linear links, network rings and meshednetworks.

Equipment (EPS) and network (MSP) protection mechanism

Matrix capacity

96*96 stm-1 equivalent matrix(HO)64*64 stm-1 equivalent matrix(LO)

Network interfaces: Stm-1/4/16

Customer interfaces: 2Mbps,34/45Mbps,140Mbps,ethernet,gigaethernet



20/46

PONDICHERRY CUDDALORE CHIDAMBARAM KUMBAKONAM

TANJORE TRICHY

ALCATEL SDH LINK-17 PONDY TOTRICHY: STM 4 LINK

26km 49km 65km

50km 54km

TotalPondy Trichy : 244 KMS

FiberOwner : BTSOL

Fiberallotted forvsnl/Ttsl : F no 39 F no 48

Fiberused forSDH : F no 43&44

Link name & no : SDH LINK No 17


21/46

Alcatel 1662 SMC Introduction Shelf View:

- Total Slots : 20

- Access Area 1: Slot 1-5 ( Hosts Access Cards like A63E1, A4S1, Congi ,etc).

- Access Area 2: Slot 16-20 ( Hosts Access Cards like A63E1, A4S1, Sergi ,etc).

- Port(Basic area)Area: Slot 6-15 (Hosts Port Cards like SYNTH, P4S1, P63E1, etc).

ACCESS AREA-1 PORT AREA ACCESSAREA-2


22/46

CARDS USED IN THE ALCATEL SDH LINK-17

1. Congi card : It the used to control the whole SDH system. It consists

of power supply&house keeping unit. the congi card is in slot no1

2. Synth4Card: It is card used to insert the optical signals from the

fms.It consists the Optical module it is named as IL- 4.2,IL-1.2,IS-1.1.- these are calledOptical modules. There are two synth cards its

inserted in slot no 6&15.

3. P4S1N card: P indicates Port ,S1N indicates STM1. card

4. P63E1 card : P indicates port, 63E1 indcates Electical signals.

5. A63E1-120 : its a card corresponding to P63E1 card.A indicates

access area.

6. LSPORT/HSPROT: Its is a Low Speed/High speed protection Card.

It is used to implement EPS protection.(i.e)it implements the

connection between the access and spare card.These cards receive

the signal coming from the access card via back panel.


23/46

7.SERGI CARD: Used as a stand by card for the CONGI CARD

8. IL- It indicates LONG HAL it should in corresponding SYNTH CARD.9. IS- It indicates SHORT HAL .

Note:

1. For All cards corresponding stand by cards are used.

2. Inserting a port card we have to insert a corresponding acess card in

the particular slot.3. Port area : Corresponding Acess area

Slot No-7 : No-2

Slot No-8 : No-3Slot No-9 : No-4

Slot No-10 : No-5

Slot No-11 : No-16Slot No-12 : No-17

Slot No-13 : No-18

Slot No-14 : No-19

4. Congi card in Slot no- 1

5. Sergi card in Slot no-20

6. Synth card in slot no:6,15


24/46

Alcatel 1662 SMC Introduction Commonly Used Cards:

P63E1 processes 63 2Mbits/s signals whose accesses are on the relevant

Access cards A21E1,A63E1 P4ES1N handles four electrical STM-1 Signals.All four accesses are on the

relevant access card(A4ES1).It is one of the board that can be EPS

protected.

P3E3T3 Prt card is a bi-directional interface from/to three PDH streams at

34Mbits/s or at 45Mbits/s Switchable and the STM-4

(1) MulticolorLED:

Red led . localunitalarm

Greenled . inserviceunit

Orangeled . unitinstand-by (EPS schema)

ACRONYM SLOTS

P63E1N 7,8,9,10,11,12,13,14

P4ES1N 7,8,9,10,11,12,13,14

P3E3T3 7,8,9,10,11,12,13,14


25/46

Alcatel 1662 SMC Introduction Commonly Used Cards ( continues..):

P4ES1N handles four electrical STM-1 signals.All the four accesses

are on the Relevant Access card(A4ES1).It can be EPS protected.

P4E4N it describes the same features of P4S1N.

Two STM-1 electrical modules(Electricl or optical )can be hosted on the board.

Two further STM-1 modules can be hosted on the Access card A2S1

LEGEND:

(1) Channel #1 (N.B.)(2) Channel #2 (N.B.)

(3) Bicolor LED:

Red led . local unit alarm

Green led . in service unit

ACRONYM SLOTS

P4ES1N 7,8,9,10,11,12,13,14

P4E4N 7,8,9,10,11,12,13,14


26/46


1662SM-C houses two congi card(i.e)congi-A and congi-B CONGI-A hold the Equip MAC(media access control) address

LEGEND:

(1) Power

(2) Housekeeping and remote alarm

(3) Rack lamp (not used in slot 20)

(4) QMD Q2 (not used in slot 20)

(5) I/O BNC Q3 10base2 (not used in slot 20)

(6) RJ45 Q3 10baseT (not used in slot 20)

(7) Bicolor LED:



ACRONYM SLOTS

CONGI 1, 20


27/46


Sergicard Providesreduced combinationofcongiand servicecard functions

IthasPowerinterface,Auxillaryinterface,I/po/pclock interface forNE synchronization

LEGEND:

(1)Power

(2) Auxiliarychannels:2 channels G.703

2 channels RS232

2 channels V.11

(3) Auxand Sync. 2Mbit/s

J1 . 2MHz Input (T3)or2Mbit/s Input (T6)

J2 . 2Mbit/s Inputchannel

J3 . 2MHzoutput (T4)or2Mbit/soutput (T5)

J4 . 2Mbit/soutputchannel

(4) Fourwiretelephoneextersionpoint (RJ11)(5) Z1-Z4 EOWzoneselection LEDs (N.B.1)

(6) L1-L2 LEDsstatus forselectiveand multiple

call (N.B.2)

(7) Telephone jack

(8) LineseizureKey

(9) EOWzoneselectionKey

(10) Resetcommand Key

(11)BicolorLED:

Red led . loca

lunita

la

rmGreenled . inserviceunit

ACRONYM SLOTS

SERGI 20


28/46


SYNTH16 can be EPS 1+1 Protected

Slot no:6 is main card

Slot no:15 is spare card

Synth16 card is equipped with two parts for modules

1*STM-16 signals can be processed by the SYNTH 16 card

Synth 16 card performs several fns like shelf controller,Equip controller,

Performance monitoring collection,remote inventory

Synth 16 cards have a 96*96 stm-1 Matrix capacity.

It is also called as Compact ADM16 Card

LEGEND

(1) Resetcommand key

(2) Channel #1 (N.B.)

(3) Lamptestpushbutton

(4)Personal ComputerConnector(F interface)

(5) Red LED . Urgent Alarm (CriticalorMajor)

(6) Red LED . Not Urgent Alarm (Minor)

(7) Yellow LED . Alarmstoring (Attended)(8) Yellow LED . Abnormalcondition

(9) Yellow LED . Indicative Alarm (Warning)

(10) Green LED . whenonitmeansactiveunit

whenoffitmeansstandbyunit

(11)BicolorLED:

Red led . localunitalarm (INT)


(12) Alarmstoringpushbutton (Attended)

ACRONYM SLOTS

SYNTH16 6,15


29/46


Commonly Used Cards ( continues..):

A63E1 is the access card for the P63E1

63*2Mbit/s Access card(A63E1)Provides the connections from backpanel

to the external line and vice versa for the 63 PDH signals. Three different type of connectors available:

A63E1/A:75 ohms unbalanced

A63E1/B:120 ohms balanced

A63E1/C:75 Ohms unbalanced with coax(3 slot wide)

LEGEND

(1) Channel #1-7

(2) Channel #8-14

(3) Channel #15-21

(4) Channel #22-28

(5) Channel #29-35

(6) Channel #36-42

(7) Channel #43-49

(8) Channel #50-56(9) Channel #57-63

ACRONYM SLOTS

A63E1B (120Ohm) 2,3,4,5,16,17,18,19


30/46


A2S1 is the access card for the P4S1N and P4E4N port cards.

A2S1 can host upto 2modules(optical stm-1) in the front panel.

LEGEND



(3)BicolorLED:



ACRONYM SLOTS

A2S1 2,3,4,5,16,17,18,19


31/46


A3E3 Provides 3*34Mbit/saccesses fortheP3E3T3

A3T3 Provides 3*45Mbit/saccesses fortheP3E3T3

ForeachP3E3T3 One A3E3,A3T3 isnecessary

LEGEND

(1) Channel #1

(2) Channel #2

(3) Channel #3(4)BicolorLED:



ACRONYM SLOTS

A3E3 2,3,4,5,16,17,18,19

A3T3 2,3,4,5,16,17,18,19


32/46


A4ES1 Provides 4 STM-1 Accesses fortheP4ES1N.

ForeachP4ES1N one A4ES1 is Necessary

LEGENDA

(1) Channel #1

(2) Channel #2

(3) Channel #3

(4) Channel #4

(5)BicolorLED:



ACRONYM SLOTS

A4ES1 2,3,4,5,16,17,18,19


33/46


34/46


LEGENDA

(1) Multicolor LED:


Orange led . temperature major than 55 C


(2) Battery A connector

(3) Battery B connector

(4) Alarms connector for 1662SMC on the Left side of the Rack

(5) Not used

(6) Alarms connector for 1662SMC on the Right side of the Rack (6)


35/46

PSC frontview

HWF

POWER

+ VBATT (male)

GND (female)

-VBATT (male)


36/46

Alcatel 1662 SMC Introduction Technical Specifications:

Safty First-

Theopticalinterfaces whichhave HAZARD LEVEL 3A (see Table A below )carrythe followinghazard symbol

label:

Caution: Invisible LaserRadiationmaybepresentinsidetheopticalinterfacescarryingtheabovelabel,hence

NEVER directlyview intothebeam.Doingsomayresultinthepermanent damagetotheeyesight.

UNIT/PORT OPTICAL INTERFACE HAZARD LEVEL

STM.1 S.1.1 (short haul) 1

STM.1 L.1.1 (long haul) 3A


STM.4 S.4.1 (short haul) 1



STM.16 S.4.1 (short haul) 3A




37/46

CLASSIFICATION OF ALARMS

SEVERITY ALARMS SYNTHESIS1.Critical Alarms

2.MajorAlarms

3.MinorAlarms

4.Warning Alarms

5.Intermediate Alarms

DOMAIN ALARMS SYNTHESIS1.Synchronization Alarms

2.Externalpoints(House keeping Alarms)

3.Transmission Alarms

4.Equipment Alarms

MANAGEMENT ALARMS SYNTHESIS

1.Supervision2.Alignment

3.Localaccess

4.Operatingsystem

5.Managed by Nm & RM

6.Abnormalcondition


38/46

Power-48V DC, 6A

MCB Ratingused inthe TRU unitis 16A

Themaxcurrentconsumed bythe Equipmentislessthan 4Amps

A/C environment withtemperature,humidityand dustcontrol

Firesafetybycentralised monitoringand automaticoperationofextinguisher

LCT accessthrough Q interface forNMS accessthroughthe LAN card

Tools:Powersource,powermeter, OTDR (Optical Time Domain Reflectometer)and OSA (Optical Spectrum Analyser)


39/46

Technical Specifications (Continues):

Electrical Interface Characteristics-


Interface Charaterisitics

P63E1 Bit rate 2048 Kbit/s 50 ppm

No. of channels 63

Line Code HDB3

Signal amplitude 2.37 Vp on 75 Ohm

unbalance/ 3 Vp on 120O

hm balance.P3E3 Bit Rate 34368 Kbit/s 20 ppm

No. of tributaries 3

Line Code HDB3

Signal amplitude 1Vp/75ohms

P3T3 Bit rate 44.736 Kbit/s 20ppm

No. of tributaries 3

Line Code B3ZS

P4S1E Bit rate 155 520 Kbit/s 20 ppm

Line Code CMI

P4E4 Bit rate 139264 Kbit/s 15 ppm

Line Code CMI


40/46

Alcatel 1662 SMC Introduction Technical Specifications (Continues):

Optical Characteristics

STM-1 S 1.1 L 1.1 L 1.2

TransPower -15 to -8dB 0 to - 5dB0 to -5dB

Receiver

Sensitivity -28dB -37dB -37dB

ReceiverOverload -8dB -10dB -10dB

Optical Connectors FCPC/SCPCSTM-4 S 4.1 L 4.1 L 4.2

TransPower -15 to -8dB 2 to -3dB2 to -3dB

Receiver


ReceiverOverload -8dB -8dB -8dB

Optical Connectors FCPC/SCPC

STM-16 S 16.1 L 16.1 L 16.2

TransPower 0 to -5dB 2 to -2dB

2 to -

2dB

Receiver


ReceiverOverload 0dB -8dB -8dB


41/46

RS232 Pin Assignments (DB9 PC signalset)

Pin 1 Received Line Signal Detector(Data Carrier Detect)

Pin 2 Received Data

Pin 3 Transmit Data

Pin 4 Data Terminal Ready

Pin 5 Signal Ground

Pin 6 Data Set Ready

Pin 7 Request To Send

Pin 8 ClearTo Send

Pin 9 Ring Indicator

The connector on the PC has male pins, therefore the mating

cable needs to terminate in a DB9/F (Female pin) connector


42/46

PROTECTION TYPES

EPSEquipment

ProtectionSwitching

MSPMultiplex

SectionProtection

1:1

1:N

MSP-LINEAR

MS-SP RING

SNCP/NSNCP/I

EPS:Protection against the equipment failure MSP:Protection against the equipment failure

And the Line Failure


43/46

EPS(EquipmentProtection Switching)

EQUIPMENT 1

EQUIPMENT 2

1.The 1+1 EPS Protectiontypemeansthatone workingequipisProtected by One Redundant Equip

2.Themodeof 1+1 EPS Protectionis Non Revertive.

1+1 Type


44/46

EPS(EquipmentProtection Switching)

1:N Type

EQUIPMENT 1

EQUIPMENT 1

EQUIPMENT N

EQUIPMENT P

LINE 1

LINE 2

LINE N

1)1:N Type protection means that N working Pieces of equip are protected

by just 1 Portecting Equivalent.

2)The mode of 1:N Eps protection is revertive.


45/46

MSP(Multiplex SectionProtection)

MSP(linear) is also called as APS(Automatic Protection Switching)

NE-A NE-B

1+1Protection

1:1Protection

1:N Protection

TX

RX

RX

RX

TX

TX

WORKING

PROTECTION

HIGH PRIORITY LINE WORKING

LOWPRIORITY LINE WORKING

TX

TX

RX

RX

WORKING

WORKING

PROTECTION


46/46

78728747 77328883 alc sdh basics and alcatel sdh system training presentation 46 slide

Documents