By-:Er. Amit Mahajan

MULTIPLEXING IN

SONET

Introduction to SONET

• SONET stands for “Synchronous Optical Network”, and Is a method for communicating digital information using laser or LED’s and a single clock is used to handle the timing, control and functionality of all the network equipments .

CPE TX

CPERX

LED RX

FIBER

Introduction to SONET

• SONET is a standard, which is established in United States of America and in Canada, while a similar standard synchronous digital hierarchy (SDH) is established in Europe.

• Basic building block of SONET is STS-1 51.840 Mbps

• SDH = STM-1 = 155.520 Mbps

SONET Multiplexing

DS3

44.736

DS1 1.544

DS2 6.312

E1 2.048

ATM

150 Mbps

STS-1

STS-1

STS-1

STS-1

STS-1

STS-3c

OC-n

Scrambler E/O

51.84 Mbps

Overhead

STS Mux

STS-nllll

ll

Overhead

Overhead

SONET Frame90

9

90*9*8 bits/byte * 8000 frames/sec = 51.840 Mbps

(125 micro second = 8000 frames/second)

SONET Frame

86*9*8*8000= 49.536 Mbps

Hence the maximum efficiency of the frame is = 49.536/51.840=95.5%

An 2.488 gigabit/sec SONET STS-1 TO STS-48 Byte Multiplexer and De-multiplexer.

• This paper describes the Architecture, Implementation and Results of high speed components of the byte multiplexer and de-multiplexer.

Architecture

De-Mux / Framer Works at

higher speed

Works at lower speed

Consists of byte alignment

circuitry, and pattern detector(A1A1A1A2A2A2)

Program 1library IEEE;use IEEE.STD_LOGIC_1164.all;

entity mux is port( a : in STD_LOGIC; clk : in STD_LOGIC; b : buffer STD_LOGIC; c : buffer STD_LOGIC );

end mux;

--}} End of automatically maintained section

architecture mux of mux is constant M_d:time:=10ns;

begin pmux:process(a,clk)variable temp1:std_logic ; variable temp2:std_logic ;begin if clk'event and clk='1' then temp1:=a; b<=temp1 after M_d;

end if;if clk'event and clk='0' then temp2:=a; c<=temp2 after M_d;end if;c<=temp2 after M_d;end process pmux;

-- enter your statements here --

end mux;

program 2(cascaded multiplexer)library IEEE;use IEEE.STD_LOGIC_1164.all;

entity mux is port( a : in STD_LOGIC; clk: in STD_LOGIC; ctrl: in std_logic_vector(0 to 1); b : buffer STD_LOGIC; c : buffer STD_LOGIC; d,e,f,g : buffer STD_LOGIC; h,i,j,k : buffer STD_LOGIC );

end mux;

--}} End of automatically maintained section

architecture mux of mux is constant M_d:time:=10ns;

begin pmux:process(a,clk,ctrl)variable temp1:std_logic ; variable temp2:std_logic ;variable temp3:std_logic ;variable temp4:std_logic ; variable temp5:std_logic ;variable temp6:std_logic ;variable temp7:std_logic ; variable temp8:std_logic ;variable temp9:std_logic ; variable temp10:std_logic ;variable temp11:std_logic ; variable temp12:std_logic ;

begin

program 2(cascaded multiplexer)if clk'event and clk='1' then temp1:=a; b<=temp1 ;case ctrl iswhen "00"=> temp3:=b;when "01"=> temp4:=b;when "10"=> temp5:=b;when "11"=> temp6:=b;when others =>temp12:='X';end case;

end if;if clk'event and clk='0' then temp2:=a; c<=temp2;case ctrl iswhen "00"=> temp7:=c;when "01"=> temp8:=c;when "10"=> temp9:=c;when "11"=> temp10:=c;when others =>temp11:='X';end case;

end if;d<=temp3;e<=temp4; f<=temp5;g<=temp6;h<=temp7;i<=temp8;j<=temp9;k<=temp10;

end process pmux;

-- enter your statements here --

end mux;

Output waveforms

Mux / Phase Aligner

It aligns the phase of the external byte clock with the on-chip byte

clock

Result and conclusion

• When de-mux/framer and mux/phase aligner are connected back to back separately. They give BER 10-12.

• When the total architecture are connected back to back. BER is 10-11 .

Metro- Ring Case StudyTDM Upgrade path

WDM upgrade path-: we build multiple virtual rings at different wavelengths over the same pair of fiber.

Let it be working at speed OC-3. suppose the capacity on the ring is exhausted and Only a pair of fiber is available, i.e. no spare fiber available

Metro- Ring Case Study

Metro- Ring Case Study

Metro- Ring Case StudyCONCLUSION

The TDM upgrade is not future proof, while the WDM upgrade path more future proof as the capacity of the existing ring is future scalable by adding additional ADMs at different wavelengths. Although we can increase the capacity of the existing ring by using TDM upgrade but at higher cost of scrap. The analysis clearly shows that, if we have exhausted ring at lower bit-rate then the TDM upgrade path is followed as compared to WDM. But at higher bit-rates above OC-48 the WDM upgrade path is more future proof and cost effective.

References

1. Network For Computer Scientists and Engineer by Shakhil Akhatar.2. ATM Transport and Integrity By Tosng- Ho-Wo And Noriaki Yoshikai.3. SONET/SDH Demystify by Steven Shaperd.4. Optical N/w Design and Implimentation by Vivek Alwayn.5. D.K. Mynbaeu & L. Scheiner, ‘Fiber optic Communication

Technology, Pearson Edu. Asia 6. Uyless Black, ‘Optical Networks’, Pearson education7. Optical Network by Rajiv Raja swami .8. Mehcan Bagheri, Dennis T. Kong, Wayne S. Holden, Fernando C.

xrizany, Derek D. Mahoney, and Douglas C. Larson “An Experimental 2.488 Gigabit/Sec SONET STS-3C to STS-48 byte Multiplexer And Demultiplexer”

References

9. Data Communications and Networking by Behrouz A Forozan.

10.Online lecture (in CD )11.Synchronous Optical Network; R.J. Riehl;

Defence Information Systems Agency.12.Computer Communications; K.G. Beauchamp

and G.S.Poo; International Thompson Computer Press.

THANK YOU

Section overhead A1,A2-:used to identify the

beginning of the frame to receiving equipment for synchronization purposes. The pattern is the hexadecimal number 0xF628 (1111 0110 0010 1000)

C1-: Identification byte-: to numbering the STS-1 in STS-N.

B1-: Bit interleave parity byte. E1-: which is used by the

technicians while troubleshot the network.

C1

Section overhead F1-: is user configurable and

can be employed for a variety of purposes. It is not standardized. Can be used for application management or network management.

D1,D2,D3-: DCC is a 192kbps data comm. Channel b/w section terminating devices, is used for OAM&P.

C1

R

Line Overhead H1,H2(pointer byte) H3 (Pointer Action Byte). if

more than 783 bytes are ready to be transmitted with in single 125 ms. Then it is placed in this byte.

B2-: this is a Bit interleaved parity byte for LOH and is used to carry error checking information for LOH only (not inc. SOH).

Line Overhead K1,K2

(Automatic protection switching).

D4-D12 (Data comm. Channel) is a 576kbps, OAM&P Information such as control signal, monitoring, alarm information etc.

Z1,Z2 future growth bytes. E2 Order-wire byte-: is used by

the technician as a voice channel (64kbps) while troubleshoot the network problem.

Z1 Z2

Path Overhead

J1 (Trace byte)-: used by the CPE at the end to ensure that it is properly connected to the transmitting device by using 64-byte repeating code.

B3 (path BIP) For error checking of path overheads of previous frame.

C2 (Path signal label) is used to tell a receiving device what is actually contained in the SPE. This permits the simultaneous transport of multiple traffic type.

Path Overhead

G1 (Path Status Byte) used to communicate overall transmission status of duplex circuited.

F2 (User byte) to transport network management data.

H4 (indicator) which points the starting of the virtual tributaries.

Z1,Z2,Z3 (future growth byte)

.

Pointer Bytes H1,H2

H1,H2 pointer byte-:Is a 16 bit payload pointer.

Payload pointer is only of 10 bits, corresponding 783 locations in SPE ( 86*9= 783 ).

Pointer Bytes H1,H2IF payload starts from the beginning of the byte then no proplem.

IF payload starts from 1st bit of the byte in SPE, then no problem. It can be easily predicted by last 10 bits.

1 BYTE in SPE

Pointer Bytes H1,H2IF payload starts from the beginning of the byte then no proplem.

If starts from 4th bit, the exact location can be detected by NDF.

1 BYTE in SPE

R

.

K1,K2(Automatic protection switching).

• In case of failure of one fiber it automatically route the traffic on the backup fiber.

R

C2 (Path signal label)