What is ISDN?INTEGRATED SERVICES DIGITAL NETWORK

• ISDN is a set of standards which define an end to end Digital Network

Features of ISDN

• Uses Digital Signal

• Uses Existing telephone wiring

• Charges are generally based on the duration of call (How long the WAN link was used)

• Alternate to using leased lines

• Can transport many types of Network traffic (Voice, Data, Video, Text, Graphics etc)

• Faster Data transfer rate than modems

• Faster Call setup than Modems

ISDN Components

ISDN Components• Terminal Equipment type 1 (TE1)

A TE is any piece of communicating equipment that complies with the ISDN standards. Examples include: digital telephones, ISDN data terminals, Group IV Fax machines, and ISDN-equipped computers.

• Terminal Equipment type 2 (TE2)

* ISDN Non-compatible devices.

* Will require a terminal adapter.

• Terminal Adapter (TA) * Converts standard electrical signals into the form used by ISDN

* Needed for connection with TE2 devices

* The ISDN TA can be either a standalone device or a board inside the TE2

Terminal Adapter (TA) •Converts standard electrical signals into the form used by ISDN

Network Termination (NT1 and NT2)The NT devices, NT1 and NT2, form the physical and logical boundary between the customer's premises and the carrier's network. NT1 performs the logical interface functions of switching and local-device control (local signalling).

NT2 performs the physical interface conversion between the dissimilar customer and network sides of the interface.

ISDN Components

ISDN Components• Exchange Termination (ET)

The ET forms the physical and logical boundary between the digital local loop and the carrier's switching office.

It performs the same functions at the end office that the NT performs at the customer's premises.

ISDN Reference pointsReference points are a series of specifications that define the connection between specific devices, depending on their function in the end-to-end connection

ISDN Reference pointsThe ISDN standards specify four distinct interfaces in the customer's connection to the network: R, S, T, and U.

The R InterfaceThe interface at reference point R is the physical and logical interface between a non-ISDN terminal device and a terminal adapter (TA).

The S InterfaceThe interface at reference point S is the physical and logical interface between a TE (or TA) and an NT.

The T InterfaceThe interface at reference point T is the physical and logical interface between NT1 and NT2, whenever the two NTs are implemented as separate pieces of hardware.

ISDN Reference pointsThe U InterfaceThe interface at reference point U is the physical and logical interface between NT (or NT2) and the ISDN carrier's local transmission loop.

Telecommuter/Remote User

Using Modem>

Using ISDN>

ISDN ServicePRI (Primary Rate Interface)• ISDN Primary Rate Interface service provides digital access via a T1

line. A T1 line provides a 1.544 bandwidth. This bandwidth is divided into 24 64Kb channels. The ISDN PRI service uses 23 B channel access and uses the 24th (D) channel for signaling purposes

ISDN ProtocolsProtocols which start with the following letter:

• E - Protocols recommend telephone network standards for

ISDN

• I - Protocols for Concepts, terminology and general methods

• Q - Protocols, how switching and signaling should operate,

call setup etc.

Dial on Demand Routing• ISDN LAN routers provide routing between ISDN BRI and the LAN

by using dial-on-demand routing (DDR)

• DDR automatically establishes and releases circuit-switched calls, providing transparent connectivity to remote sites based on networking traffic

• DDR also controls establishment and release of secondary B channels based on load thresholds

Cellular Radio Networks

Cellular Radio NetworksA cellular network is a radio network distributed over land areas called cells, each served by at least one fixed-location transceiver known as a cell site or base station.

When joined together these cells provide radio coverage over a wide geographic area. This enables a large number of portable transceivers (e.g., mobile phones, pagers, etc.) to communicate with each other and with fixed transceivers and telephones anywhere in the network, via base stations, even if some of the transceivers are moving through more than one cell during transmission.

Advantages

Cellular networks offer a number of advantages over alternative solutions:

1) Increased capacity2) Reduced power use3) Larger coverage area4) Reduced interference from other signals

The Concept

The ConceptWhy Called Cellular Network?

In a cellular radio system, a land area to be supplied with radio service is divided into regular shaped cells, which can be hexagonal, square, circular or some other irregular shapes, although hexagonal cells are conventional.

Each of these cells is assigned multiple frequencies (f1 - f6) which have corresponding radio base stations.

The ConceptWhat is Frequency Reusing?

In a cellular radio system, the group of frequencies can be reused in other cells, provided that the same frequencies are not reused in adjacent neighboring cells.

The elements that determine frequency reuse are the reuse distance and the reuse factor.

The reuse distance, D is calculated aswhere R is the cell radius and N is the number of cells per cluster. Cells may vary in radius in the ranges (1 km to 30 km)

Directional antennas

A cellular map can be redrawn with the cellular telephone towers located at the corners of the hexagons where three cells converge. Each tower has three sets of directional antennas aimed in three different directions with 120 degrees for each cell (totaling 360 degrees) and receiving/transmitting into three different cells at different frequencies. This provides a minimum of three channels (from three towers) for each cell.

Handoff

In a cellular system, as the distributed mobile transceivers move from cell to cell during an ongoing continuous communication, switching from one cell frequency to a different cell frequency is done electronically without interruption and without a base station operator or manual switching.

This is called the handover or handoff. Typically, a new channel is automatically selected for the mobile unit on the new base station which will serve it. The mobile unit then automatically switches from the current channel to the new channel and communication continues.

Example of a cellular radio network

The most common example of a cellular radio network is a mobile phone (cell phone) network.

A mobile phone is a portable telephone which receives or makes calls through a cell site (base station), or transmitting tower. Radio waves are used to transfer signals to and from the cell phone.

There are a number of different digital cellular technologies, including: 1) Global System for Mobile Communications (GSM), 2) Code Division Multiple Access (CDMA), 3) Evolution-Data Optimized (EV-DO), 4) Digital Enhanced Cordless Telecommunications (DECT), 5) Digital AMPS (IS-136/TDMA), 6)Integrated Digital Enhanced Network (iDEN).

Intelligent network

The Intelligent Network, typically stated as its acronym IN, is a network architecture intended both for fixed as well as mobile telecom networks.

It allows operators to differentiate themselves by providing value-added services in addition to the standard telecom services such as PSTN, ISDN and GSM services on mobile phones.

Examples of IN services

1) Televoting 2) Call screening 3) Telephone number portability 4) Toll free calls / Freephone 5) Prepaid calling 6) Account card calling 7) Virtual private networks (e.g. : Family group calling) 8) Private-number plans 9) Mass-calling service 10) Prefix free dialing 11) Call Queueing 12) Call transfer

History and key concepts

The major driver behind the development of the IN system was the need for a more flexible way of adding sophisticated services to the existing network. Before IN was developed, all new feature and/or services that were to be added had to be implemented directly in the core switch systems.

This made for very long release cycles as the bug hunting and testing had to be extensive and thorough to prevent the network from failing.

Main Concepts - SS7 Architecture

Service Switching Function (SSF) or Service Switching Point (SSP) This is co-located with the telephone exchange itself, and acts as the trigger point for further services to be invoked during a call.

Service Control Function (SCF) or Service Control Point (SCP) This is a separate set of platforms that receive queries from the SSP. The SCP contains service logic which implements the behaviour desired by the operator, i.e., the services.

Service Data Function (SDF) or Service Data Point (SDP) This is a database that contains additional subscriber data, or other data required to process a call.

Main Concepts - SS7 Architecture

Service Management Function (SMF) or Service Management Point (SMP) This is a platform or cluster of platforms that operators use to monitor and manage the IN services.

Service Creation Environment (SCE) This is the development environment used to create the services present on the SCP. Although the standards permit any type of environment, it is fairly rare to see low level languages like C used.

Specialized Resource Function (SRF) or Intelligent Peripheral (IP) This is a node which can connect to both the SSP and the SCP and delivers additional special resources into the call, mostly related to voice data

Main Concepts - SS7 Architecture

Benefits of SS7

• Major benefits include– improves the speed and flexibility of call setup– allows processors to exchange information

rapidly for a call requiring special routing or handling

– enables operation companies to access customer information stored in network databases to deliver advanced telecommunications services network wide

Intelligent Network - Summary

• Intelligent Network, IN offers– Open standards, vendor independence– Rapid service creation and deployment– Total network and customer management– Customized services to users– New opportunities to make business ie. new

markets and customers– Rapid adaptation to market needs and

competition Competitive edge

Private Network

In the Internet addressing architecture, a private network is a network that uses private IP address space

Computers not connected to the Internet, such as factory machines that communicate only with each other via TCP/IP, need not have globally unique IP addresses. Three ranges of IPv4 addresses for private networks were reserved in RFC 1918. These addresses are not routed on the Internet and thus their use need not be coordinated with an IP address registry.

Private network

These addresses are characterized as private because they are not globally delegated, meaning they are not allocated to any specific organization, and IP packets addressed by them cannot be transmitted onto the public Internet.

Anyone may use these addresses without approval from a regional Internet registry (RIR).

If such a private network needs to connect to the Internet, it must use either a network address translator (NAT) gateway, or a proxy server.

Private network

Private IPv4 address spaces

The Internet Engineering Task Force (IETF) has directed the Internet Assigned Numbers Authority (IANA) to reserve the following IPv4 address ranges for private networks, as published in RFC 1918

Private IPv6 address spaces

The concept of private networks and special address reservation for such networks has been carried over to the next generation of the Internet Protocol, IPv6.

The address block fc00::/7 has been reserved by IANA as described in RFC 4193. These addresses are called Unique Local Addresses (ULA). They are defined as being unicast in character and contain a 40-bit random number in the routing prefix to prevent collisions when two private networks are interconnected. Despite being inherently local in usage, the IPv6 address scopes of unique local addresses is global.

Common Uses

The most common use of private networks are for residential n/w purpose, since most Internet service providers (ISPs) only allocate a single routable IP address to each residential customer, but many homes have more than one computer or other Internet connected device, such as televisions.

In this situation, a network address translator (NAT) gateway is usually used to provide Internet connectivity to multiple hosts.