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• 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
ISDN ComponentsTerminal Adapter (TA)•Converts standard electrical signals into the form used by ISDNNetwork Termination (NT1 and NT2)The NT devices, NT1 and NT2, form the physical and logicalboundary between the customers premises and the carriers network.NT1 performs the logical interface functions of switching and local-device control (local signalling).NT2 performs the physical interface conversion between thedissimilar customer and network sides of the interface.
ISDN Components• Exchange Termination (ET) The ET forms the physical and logical boundary between the digital local loop and the carriers switching office. It performs the same functions at the end office that the NT performs at the customers premises.
ISDN Reference pointsReference points are a series of specifications thatdefine the connection between specific devices,depending on their function in the end-to-endconnection
ISDN Reference pointsThe ISDN standards specify four distinct interfaces in the customersconnection to the network: R, S, T, and U.The R InterfaceThe interface at reference point R is the physical and logicalinterface between a non-ISDN terminal device and a terminal adapter(TA).The S InterfaceThe interface at reference point S is the physical and logical interfacebetween a TE (or TA) and an NT.The T InterfaceThe interface at reference point T is the physical and logical interfacebetween NT1 and NT2, whenever the two NTs are implemented asseparate pieces of hardware.
ISDN Reference pointsThe U InterfaceThe interface at reference point U is the physical and logicalinterface between NT (or NT2) and the ISDN carriers localtransmission 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 NetworksA cellular network is a radio network distributed overland 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 coverageover a wide geographic area. This enables a large numberof portable transceivers (e.g., mobile phones, pagers, etc.)to communicate with each other and with fixed transceiversand telephones anywhere in the network, via base stations,even if some of the transceivers are moving through morethan one cell during transmission.
AdvantagesCellular networks offer a number of advantages over alternativesolutions:1) Increased capacity2) Reduced power use3) Larger coverage area4) Reduced interference from other signals
The Concept Why Called Cellular Network?In a cellular radio system, a land area to be supplied with radio serviceis divided into regular shaped cells, which can be hexagonal, square,circular or some other irregular shapes, although hexagonal cells areconventional.Each of these cells is assigned multiple frequencies (f1 - f6) which havecorresponding radio base stations.
The Concept What is Frequency Reusing?In a cellular radio system, the group of frequencies can be reused inother cells, provided that the same frequencies are not reused inadjacent neighboring cells.The elements that determine frequency reuse are the reuse distance andthe reuse factor.The reuse distance, D is calculated aswhere R is the cell radius and N is the number of cells per cluster. Cellsmay vary in radius in the ranges (1 km to 30 km)
Directional antennasA cellular map can be redrawn with thecellular telephone towers located at thecorners of the hexagons where threecells converge. Each tower has threesets of directional antennas aimed inthree different directions with 120degrees for each cell (totaling 360degrees) and receiving/transmittinginto three different cells at differentfrequencies. This provides a minimumof three channels (from three towers)for each cell.
HandoffIn a cellular system, as the distributed mobile transceivers move fromcell to cell during an ongoing continuous communication, switchingfrom one cell frequency to a different cell frequency is doneelectronically without interruption and without a base station operator ormanual switching.This is called the handover or handoff. Typically, a new channel isautomatically selected for the mobile unit on the new base station whichwill serve it.The mobile unit then automatically switches from the current channel tothe new channel and communication continues.
Example of a cellular radio networkThe 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 callsthrough a cell site (base station), or transmitting tower. Radio waves areused 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 DivisionMultiple Access (CDMA), 3) Evolution-Data Optimized (EV-DO), 4)Digital Enhanced Cordless Telecommunications (DECT), 5) DigitalAMPS (IS-136/TDMA), 6)Integrated Digital Enhanced Network(iDEN).
Intelligent networkThe Intelligent Network, typically stated as its acronym IN, is anetwork architecture intended both for fixed as well as mobiletelecom networks.It allows operators to differentiate themselves by providing value-added services in addition to the standard telecom services such asPSTN, ISDN and GSM services on mobile phones.
Examples of IN services1) Televoting2) Call screening3) Telephone number portability4) Toll free calls / Freephone5) Prepaid calling6) Account card calling7) Virtual private networks (e.g. : Family group calling)8) Private-number plans9) Mass-calling service10) Prefix free dialing11) Call Queueing12) Call transfer
History and key conceptsThe major driver behind the development of the IN system was the needfor a more flexible way of adding sophisticated services to the existingnetwork.Before IN was developed, all new feature and/or services that were to beadded had to be implemented directly in the core switch systems.This made for very long release cycles as the bug hunting and testinghad to be extensive and thorough to prevent the network fromfailing.
Main Concepts - SS7 ArchitectureService Switching Function (SSF) or Service Switching Point (SSP)This is co-located with the telephone exchange itself, and acts as thetrigger point for further services to be invoked during a call.Service Control Function (SCF) or Service Control Point (SCP) Thisis a separate set of platforms that receive queries from the SSP. The SCPcontains service logic which implements the behaviour desired by theoperator, i.e., the services.Service Data Function (SDF) or Service Data Point (SDP) This is adatabase that contains additional subscriber data, or other data requiredto process a call.
Main Concepts - SS7 ArchitectureService Management Function (SMF) or Service Management Point(SMP) This is a platform or cluster of platforms that operators use tomonitor and manage the IN services.Service Creation Environment (SCE) This is the developmentenvironment used to create the services present on the SCP. Althoughthe standards permit any type of environment, it is fairly rare to see lowlevel 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 anddelivers additional special resources into the call, mostly related to voicedata
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 networkIn the Internet addressing architecture, a private network is a networkthat uses private IP address spaceComputers not connected to the Internet, such as factory machines thatcommunicate only with each other via TCP/IP, need not have globallyunique IP addresses.Three ranges of IPv4 addresses for private networks were reserved inRFC 1918.These addresses are not routed on the Internet and thus their useneed not be coordinated with an IP address registry.
Private networkThese addresses are characterized as private because they are notglobally delegated, meaning they are not allocated to any specificorganization, and IP packets addressed by them cannot be transmittedonto the public Internet.Anyone may use these addresses without approval from a regionalInternet registry (RIR).If such a private network needs to connect to the Internet, it mustuse either a network address translator (NAT) gateway, or a proxyserver.
Private IPv4 address spacesThe Internet Engineering Task Force (IETF) has directed the InternetAssigned Numbers Authority (IANA) to reserve the following IPv4address ranges for private networks, as published in RFC 1918
Private IPv6 address spacesThe concept of private networks and special address reservation for suchnetworks has been carried over to the next generation of the InternetProtocol, IPv6.The address block fc00::/7 has been reserved by IANA as describedin 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 twoprivate networks are interconnected. Despite being inherently local inusage, the IPv6 address scopes of unique local addresses is global.
Common UsesThe most common use of private networks are for residential n/wpurpose, since most Internet service providers (ISPs) only allocate asingle routable IP address to each residential customer, but many homeshave more than one computer or other Internet connected device, such astelevisions.In this situation, a network address translator (NAT) gateway is usuallyused to provide Internet connectivity to multiple hosts.