topic 6 data network (part 2)
DESCRIPTION
Data Network (Part 2)TRANSCRIPT
-
Topic 6 (Part 2) PUBLIC DATA NETWORK
DEPARTMENT OF ELECTRICAL ENGINEERING
EP601 DATA COMMUNICATION
-
TOPIC 6 : PART 2
At the end of this learning session, student must be able to;
Define SONET
Describe Synchronous Transport Signals (STS)
Explain SONET System
Explain NGN, Internet Protocol (IP), IPv4 and IPv6
Identify NGN characteristics
State type of NGN services
-
Introduction
What is SONET / SDH???
Synchronous Optical Network ANSI (US)
Synchronous Digital Hierarchy ITU-T Europe
Similar and compatible
A standard to be used for fibre optics
Recommendation for FOTS equipment
Fibre Optic Transmission Systems
3
-
Introduction cont
SONET defines a hierarchy of electrical signaling levels called Synchronous transport signals (STSs)
SDH specifies a similar system called a synchronous transport module (STM).
It is another application of Time division Multiplexing (TDM).
That is a synchronous system controlled by master clock
4
4
-
SONET Overview
The SONET specification defines:
standard optical signals, which permits the interoperation of equipment from different manufacturers
a synchronous frame structure for multiplexing digital traffic
procedures for operations and maintenance (OAM)
5
-
SONET Overview Cont
SONET includes:
support for broadband rates
base rate approximately 50 Mbps
hierarchical family of digital rates
defines data rates up to 2.4 Gbps
synchronous multiplexing
global timing structure at physical layer
synchronous implies simpler interface 6
-
Signal Hierarchy
SONET : STS Synchronous Transport Signals
support a certain base data rate- 51.84Mbps
STS 1 STS 192 different hierarchies
Corresponding carrier System
Optical Carrier OC-1, OC-3, OC-12, OC-48
SDH : STM Synchronous Transport Module
STM 1 = STS 3
7
-
SONET/SDH rates
The lowest level or base signal is referred to as STS -1 i.e. Synchronous Transport Signal level -1 which operates at 51.840Mbps.
Higher-level signals are integer multiples of STS -1.
STS N signal is composed of N byte-interleaved STS -1 signals.
-
An STS-1 and an STS-n frame
Each frame is a two-dimensional matrix of bytes with 9 rows
by 90 n columns.
Matrix of nine rows 90 octets = 90 bytes each
9
-
STS-1 frames in transmission
Each synchronous transfer signal STS - n is composed of 8000 frames.
A SONET STS - n signal is transmitted at 8000 frames per second. Each byte in a SONET frame can carry a digitized voice channel.
-
SONET STS-1Frame
11
Frame1
Frame2
Frame8000
Frame = 810 octets * 8 = 6480bits
8000 frames/sec = 6480*8000 bits/sec = 51.84Mbps
Each synchronous transfer signal STS - n is composed of 8000 frames.
Each frame is a two-dimensional matrix of bytes with 9 rows by 90 n columns.
Bytes (octets) are transmitted one row at a time, from left to right
Note: 1 byte/frame = 64 kbps
-
STS-1 frame overheads
Frame structure: 9 rows of 90 columns of 8-bit bytes First three columns of STS-1 frame are for section overhead and line overhead Remaining 87 columns are for the Synchronous Payload Envelope (SPE) 12
-
STS-1 frame: section overhead
Overhead bytes are used by SONET equipment (e.g., switches) for exchange of control and signalling information, and as a low bandwidth data channel.
-
Find the data rate of an STS-3 signal.
Solution
STS-3, like other STS signals, sends 8000 frames per
second. Each STS-3 frame is made of 9 by (3 90) bytes. Each byte is made of 8 bits. The data rate is.
Note : In SONET, the data rate of an STS-n signal is n times the data rate of an STS-1 signal.
Example
14
-
17.
15
15
What is the duration of an STS-1 frame? STS-3 frame?
STS-n frame?
Solution
In SONET, 8000 frames are sent per second. This
means that the duration of an STS-1, STS-3, or STS-n
frame is the same and equal to 1/8000 s, or 125 s.
Example
-
A simple network using SONET equipment
16
-
STS multiplexers/demultiplexers - path terminating equipment : mark the beginning points and endpoints of a SONET link. - multiplex signals from multiple electrical sources and creates the corresponding optical signal and demultiplex an optical signal into corresponding electric signals.
- map user payload into standard frame - Header goes end-to-end as part of Synchronous Payload Envelope - SPE
SONET Devices
17
-
SONET Devices cont
Add /Drop Multiplexers
- allow insertion and extraction of signals in an STS :
an add/drop multiplexer can add an electrical
signals into a given path or can remove a desired
signal from a path.
- use header address information to identify stream
and remove
- Line terminating Equipment
- perform multiplexing, synchronization, APS
18
-
SONET Devices cont
Regenerator
- Repeater : improves signal quality by taking a
received optical signal and regenerates it.
- replaces some of the existing overhead information with new information.
- Operations include layer 2 : Frame alignment,
scrambling, error monitoring
- Section terminating equipment
19
-
SONET
Section
Connects two neighboring devices
Line
Connects two multiplexers (STS , Add/Drop)
Path
Connects two STS Mux/demux
Layers likewise path, line, section
20
-
SONET layers compared with OSI or the Internet layers
21
-
SONET layers
Photonic layers
- corresponds to the physical layer of the OSI
model.
- physical specifications for the optical fiber channel.
- NRZ encoding used : the presence of light
representing 1 and the absence of light
representing 0
Power level
Wavelength
Pulse shape
22
-
Section layer
is responsible for the movement of a signal across a physical section.
Frames : identifies beginning of frame
Scrambling : introducing 1s to derive clock
error monitoring : at section level
Adds 9 bytes to header : frame size 810 bytes
Provided at all devices 23
SONET layers cont
-
Line layer
is responsible for the movement of a signal across a physical line.
Locates partial payload virtual tributaries
Provides frequency justification, bit stuffing
To adjust to clocking from different systems
Does APS
Adds 18 bytes to header
Provided at the STS Mux and Add/Drop Mux
24
SONET layers cont
-
Path layer
is responsible for the movement of a signal from its source to its destination.
Converts to optical signals and back to electromagnetic
Adds 9 bytes to header - is part of SPE
Defines the payload being carried
End-to-end path control
Support virtual tributaries
Provided at the STS Mux 25
SONET layers cont
-
Devicelayer relationship in SONET
26
-
The next-generation network (NGN) is a body of key architectural changes in telecommunication core and access networks.
The general idea behind the NGN is that one network transports all information and services (voice, data, and all sorts of media such as video) by encapsulating these into packets, similar to those used on the Internet.
NGNs are commonly built around the Internet Protocol, and therefore the term all IP is also sometimes used to describe the transformation toward NGN.
NEXT GENERATION NETWORK
27
-
ITU-T definition of NGN (Feb 2004)
A Next Generation Network (NGN) is a packet-based network
Able to provide services including Telecommunications Services and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlying transport-related technologies.
It offers unrestricted access by users to different service providers.
It supports generalized mobility which will allow consistent and ubiquitous provision of services to users.
28
-
1990 1980 1970
NGN Long-Term Network Convergence Perspective
29
Public Switched Telecommunication Network (PSTN)
Intelligent Network Internet (IN)
Open Systems Interconnection Internet (OSI)
Commercial Mobile Radio Systems
2000
NGNs
IP Internet (IP) private quasi-public
Was never designed
as public
infrastructure
-
30
Telephone
Services
Data
Services
(WWW,
e-mail, etc)
Video
Services
(TV, movie, etc)
Telephone
Services
Network
Video
Services
Network
Data
Services
Network
Pre-NGN
Policy Area 1 Policy Area 2 Policy Area 3
Legacy: Vertically-Integrated Networks
-
Transport
Services
Telephone Services
Data Services (WWW, e-mail, etc)
Video Services (TV, movie, etc)
Point to point, Point to multipoint, Multipoint to
multipoint
Point to point, Point to multipoint, Multipoint to
multipoint
NGN - Convergence
NGN: Horizontally-Integrated Network
In an NGN, two separate policy frameworks are required: one applicable to transport networks, and another applicable to content-based services.
31
-
Internet Protocol
(IP)
Anything & Everything
Everything
Two Policy Domains
(Any & All Network technologies)
(Any/All Applications
e.g. voice , data , video)
NGN: Shape of things to come
Scope Of
Internet
Services
Transport
Note :
32
-
One network for everything
Today Tomorrow
Telephone network
Mobile radio network
IP-Network
Multimedia Access - Advantages: easy to handle reliable mobile
Internet
Transition to NGN
IP will become the networking protocol
of choice.
-
Internet Protocol (IP)
What is IP?
The Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the Internet.
When IP was first standardized in Sep 1981, each system attached to the IP based Internet had to be assigned a unique 32-bit address.
IPv4, defines a 32-bit address - 232
(4,294,967,296) IPv4 addresses available
34
-
IP Address Shortage
Proliferation of Internet devices:
405M mobile phones sold in 2000
1B+ by 2005
New emerging populations:
China, Korea, Japan, India, Russia
Solution = IPv6
35
-
Address Formats
IPv4
32-bit
Ex: 192.156.136.22
IPv6
128 bits
Ex: 1080:0:0:0:8:800:200C:417A
Or in compressed format:
1080::8:800:200C:417A
36
8 groups of 16-bit hexadecimal numbers separated by :
:: = all zeros in one or more group of 16-bit hexadecimal numbers
-
128 bits 32 bits
IPv4 & IPv6 Header Comparison
Version IHL Type of Service
Total Length
Identification Flag
s Fragment
Offset
Time to Live
Protocol Header Checksum
Source Address
Destination Address
Options Padding
Version Traffic Class
Flow Label
Payload Length Next Header Hop Limit
Source Address
Destination Address
IPv4 Header IPv6 Header
- fields name kept from IPv4 to IPv6
- fields not kept in IPv6
- Name & position changed in IPv6
- New field in IPv6 Le
ge
nd
The basic IPv4 packet header has 12 fields with a total size of
20 octets (160 bits).
20
octe
ts
The basic IPv6 packet header has 8 fields with a total size of 40 octets (320 bits).
40
octe
ts
-
Major Improvements of IPv6 Header
No option field: Replaced by extension header. Result in a fixed length, 40-byte IP header.
No header checksum: Result in fast processing.
No fragmentation at intermediate nodes: Result in fast IP forwarding.
38
-
Advantages to IPv6
Larger address space
Reduce end-to-end delay
Higher level of security (IPSec Mandated, works End-to-End )
Mobility (Mobile IP with Direct Routing)
No fragmentation
Network autoconfiguration (Serverless, Reconfiguration, DHCP
39
-
Basic characteristics of NGN
Packet-based transfer,
Separation of control functions
Decoupling of service provision
Support for a wide range of services
Broadband capabilities
Interworking with legacy networks
Generalized mobility
Unfettered access 40
-
NGN Services
Several services that will be important drivers in the NGN environment are:
1-Voice Telephony: e.g.Call Waiting, Call Forwarding, 3-Way Calling
2-Voice Portal: provide callers with anywhere, anytime access to information like news, weather, stock quotes, and account balances using simple voice commands and any telephone,..
3-Data services: bandwidth-on-demand, connection reliability/resilient ,
41
-
4-Multimedia services: This allows customers to converse with each other while displaying visual information.
5-Virtual Private Networks: allow large, geographically dispersed organizations to combine their existing private networks with portions of the PSTN, thus providing subscribers with uniform dialing capabilities.
6-Public Network Computing: Provides public network-based computing services for businesses and consumers (e.g, to host a web page, store/maintain/backup data files, or run a computing application).
42
NGN Services cont
-
7-Unified Messaging: Supports the delivery of voice mail, email, fax mail, and pages through common interfaces .
8-Information Brokering: Involves advertising, finding, and providing information to match consumers with providers.
9-E-Commerce: Allows consumers to purchase goods and services electronically over the network.
10-Call Center Services: A subscriber could place a call to a call center agent by clicking on a Web page.
11-Interactive gaming: Offers consumers a way to meet online and establish interactive gaming sessions. 43
NGN Services cont
-
12-Distributed Virtual Reality: Refers to technologically generated reperesentations of real-word events, people, places,experiences, etc., in which the participants in and providers of the virtual experience are physically distributed.
13-Home Manager: These services could monitor and control home security systems, energy systems, home entertainment systems, and other home appliances.
44
NGN Services cont
-
REFERENCES:
Main: Forouzan, B.A. (2012). Data Communications and Networking (5th edision). Mc Graw Hill. (ISBN: 978-0-07-131586-9) Additional: William Stallings. (2011). Data And Computer Communication (9th edition). Prentice Hall. (ISBN-10: 0131392050)