EGEC4120 - Telecommunication Networks Chapter 8

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Questions and Answers

What does PDH stand for?

Plesiochronous Digital Hierarchy

SDH and SONET are both terminologies associated with digital multiplexers used in exchanges.

True (A)

What is the first standardized digital higher-order transmission hierarchy developed by ITU-T and CCITT?

Synchronous Digital Hierarchy (SDH)

Plesiochronous Digital Hierarchy (PDH) (correct)

Synchronous Optical Network (SONET)

None of the above

What is the primary limitation of PDH?

All of the above (D) Signup and view all the answers

The PDH higher-order systems were standardized more than 20 years ago.

True (A) Signup and view all the answers

What was the main reason for the development of SDH?

All of the above (D) Signup and view all the answers

SDH was designed to remove synchronization problems and restore the plesiochronous digital hierarchy (PDH) system.

True (A) Signup and view all the answers

Which of the following is NOT a characteristic of SDH?

It uses a frame structure of 9 rows and 90 columns. (B) Signup and view all the answers

What is the primary function of SONET?

To transmit a large volume of data over relatively long distances using a fiber optic medium. Signup and view all the answers

Which of the following is NOT a key characteristic of SONET?

It uses a frame structure of 9 rows and 270 columns. (A) Signup and view all the answers

Which layer of the SONET architecture is responsible for the movement of signals from its optical source to its optical destination?

Path Layer (C) Signup and view all the answers

What is the basic unit of data transmission in SONET?

Synchronous Transport Signal (STS) (C) Signup and view all the answers

SONET uses STS and VT for transmission.

True (A) Signup and view all the answers

What is the fixed payload rate of SONET?

51.84 Mbps Signup and view all the answers

SDH has a fixed payload rate.

False (B) Signup and view all the answers

Which of the following is responsible for adding or removing signals in a SONET network?

Add/Drop Multiplexers (D) Signup and view all the answers

Which layer of the SONET architecture is responsible for the movement of signals across a physical section?

Section Layer (B) Signup and view all the answers

SONET uses NRZ encoding with the presence of light representing 1 and the absence of light as 0.

True (A) Signup and view all the answers

Which of the following is NOT an advantage of SONET?

Low overhead. (A) Signup and view all the answers

What is the data rate for an STS-3 signal?

155.52 Mbps Signup and view all the answers

How many DS1 channels can be multiplexed within an STS-3 frame?

100 Signup and view all the answers

What is the data rate of an OC-12 connection?

622.080 Mbps Signup and view all the answers

What is the typical data rate of an ATM cell?

424 bits Signup and view all the answers

How many ATM cells can be transmitted per second over an OC-12 connection?

1,466,981 Signup and view all the answers

Study Notes

EGEC4120 - Telecommunication Networks and Switching - Chapter 8: PDH/SDH/SONET

E-book Reference: Introduction to Telecommunications, Network Engineering (second Edition) by Tarmo Anttalainen. Available at https://ebookcentral.proquest.com/lib/uomp/reader.action?docID=227647
Course Authors: Analene Montesines Nagayo and Mohamed Yusuf Hasan
Outcome Coverage (OC 3): Design and manage a Digital Transport network such as SDH/SONET.
PDH (Plesiochronous Digital Hierarchy): An early digital hierarchy for transmission, standardized by ITU-T and CCITT. The higher-order multiplexers in PDH operate according to their own independent clock frequencies.
SDH (Synchronous Digital Hierarchy): A synchronous digital hierarchy; unlike PDH, SDH is used with digital multiplexers in exchanges, combining different hierarchies with varied bit rates.
SONET (Synchronous Optical Network): A synchronous optical network that utilizes light-emitting diodes (LEDs) or lasers for optical fiber communication. Removing synchronization problems and restoring plesiochronous digital hierarchy (PDH) systems, it was developed for bulk telephone and data exchange. It is designed for high-bit-rate optical transport, carrying all PDH types in one universal structure.
SONET Limitations: PDH systems were standardized decades ago. The need for access to tributary rates requires a step-by-step de-multiplexing process. Optical interfaces lack standardization but are vendor-specific. Network management, features, and specific interfaces from different vendors often aren't compatible. High data rates (above certain numbers) aren't standardized, copper interfaces are defined, and overhead percentage increases with rate.
SONET Layers:
- Path Layer: Responsible for signal movement from source to destination. STS Multiplexer/Demultiplexer components provide this layer's functions.
- Line Layer: Manages signal movement across a physical line. STS Multiplexer/Demultiplexer and Add/Drop Multiplexer provide the functionalities for this layer.
- Section Layer: Manages signal movement across a physical section. Each network device is responsible for functionalities at the section layer.
- Photonic Layer: Corresponds to the physical layer of the OSI model, including physical specs for the optical fiber channel.
SONET Components:
- STS Multiplexer: Multiplexes signals from various electrical sources to create optical signals.
- STS Demultiplexer: Demultiplexes optical signals into corresponding electrical signals.
- Regenerator: A repeater that regenerates and strengthens optical signals.
- Add/Drop Multiplexer: Allows inserting and removing signals from a given path.
SONET Network Topology:
- Unidirectional Path-Switched Ring (UPSR): Traffic flows in one direction around a ring. If a link fails, traffic re-routes in the opposite direction.
- Bidirectional Line-Switched Ring (BLSR): Traffic flows in both directions. When a failure occurs, traffic re-routes to a protective path on the opposite side of the ring.
SONET vs SDH:
- They are high-speed optical communication networks.
- SONET uses a 9x90 grid (9 rows, 90 columns) frame structure, while SDH uses a 9x270 grid.
- SONET uses STS (Synchronous Transport Signal) and VT (Virtual Tributary) while SDH uses STM (Synchronous Transport Module) and VC (Virtual Container).
- SONET has a fixed payload rate of 51.84 Mbps, while SDH has multiple variable payload rates, including 155.52 Mbps, 622.08 Mbps, and 2.5 Gbps.
SONET STS-1 Frame:
- 90 columns x 9 rows = 810 bytes
- 8000 frames per second
STM-1 Frame Structure has 270 columns.
SONET Advantages: Reduced network complexity, flexible topologies, high data rates, and efficient bandwidth management.
Drill Problems:
- Problem 1: Calculate the data rate and DS1 channels in a SONET STS-3 frame.
- Problem 2: Calculate the ATM cell transmission rate in an OC-12 connection. (Provides relevant example calculations.)

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Description

This quiz covers Chapter 8 of the EGEC4120 course, focusing on PDH, SDH, and SONET within Telecommunication Networks. Students will explore the design and management of digital transport networks, understanding the nuances of these technologies. Test your knowledge on the advancements and implementations of these hierarchical systems.