Presentation on theme: "Communication Systems (2) CT 1401"— Presentation transcript:
1 Communication Systems (2) CT 1401 Lecture-7: Integrated Services for Digital Network (ISDN)By : Ashwaq fahadSupervision : Dr.Ouiem Bchir
2 Integrated Services for Digital Network (ISDN) OutlineDefinition Integrated Services for Digital Network (ISDN)Types interface ISDNISDN Components and Reference PointsISDN BenefitsAdvantages and disadvantages of ISDNISDN UsesISDN ProtocolsISDN Protocol Operating OSI LayersISDN Encapsulation
3 Integrated Services for Digital Network (ISDN) DefinitionIntegrated Services for Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. It was first defined in 1988 in the CCITT red book Prior to ISDN, the telephone system was viewed as a way to transport voice 
5 Types interface ISDNCisco supports the following two ISDN interface types, which combine the channel types in the preceding list:Basic Rate Interface (BRI)— One 16-kbps D channel + two B channelsPrimary Rate Interface (PRI)— 1 64-kbps D channel + 23 B channels in North America and Japan, for a total capacity of 1536 kbps kbps D channel + 30 B channels in Europe and other parts of the world, for a total capacity of 1984 kbps.
7 ISDN Components and Reference Points Terminal Adapter (TA) - Converter device that converts standard electrical signals into the form used by ISDN - allows non-ISDN devices to operate on an ISDN network.Terminal Equipment Type 1 (TE1) - Compatible with the ISDN network. Example: Telephones, personal computers, fax machine or videoconferencing machine.Terminal Equipment Type 2 (TE2) - Not compatible with the ISDN network. Example: Analog phone or modem, requires a TA (TE2 connects to TA).Network termination type 1 & 2 (NT1 and NT2) - A small connection box that physically connects the customer site to the Telco local loop, provides a four-wire connection to the customer site and a two-wire connection to the network (PRI – CSU/DSU). 
8 ISDN BenefitsCarries a variety of user traffic, such as digital video, data, and telephone network services, using the normal phone circuit-switched networkOffers much faster call setup than modems by using out-of-band signaling (D channel)Often less than one secondProvides a faster data transfer rate than modems by using the 64-kbps bearer channel (B channel)Can combine multiple B channels to bandwidth of 128 kbpsCan negotiate PPP links 
9 Advantages and disadvantages of ISDN The basic advantage of ISDN is to facilitate the user with multiple digital channels. These channels can operate concurrently through the same one copper wire pair.The digital signals broadcasting transversely the telephone lines.ISDN provides high data rate because of digital scheme which is 56kbps.ISDN network lines are able to switch manifold devices on the single line such as faxes, computers, cash registers credit cards readers, and many other devices. These all devices can work together and directly be connected to a single lineISDN takes only 2 seconds to launch a connection while other modems take 30 to 60 second for establishment 
10 Advantages and disadvantages of ISDN The disadvantage of ISDN lines is that it is very costly than the other typical telephone system.ISDN requires specialized digital devices just like Telephone Company 
15 ISDN ProtocolsE-series protocols—Telephone network standards for ISDN.I-series protocols—Specify ISDN concepts and interfaces.Q-series protocols—Standards for ISDN switching and signaling.Operate at the physical, data link, and network layers of the OSI reference model 
16 ISDN Protocol Operating OSI Layers Physical layer ISDN protocolsBRI (ITU-T I.430) / PRI (ITU-T I.431)Defines two ISDN physical layer frame formatsInbound (local exchange to ISDN customer)Outbound (ISDN customer to local exchange ) 
18 ISDN Protocol Operating OSI Layers Data link layer ISDN protocolsLAPD signaling protocol (ITU-T Q.920 for BRI and Q.921 for PRI) for transmitting control and signaling information over the D channelLAPD frame format similar to ISO HDLC frame format 
20 ISDN Protocol Operating OSI Layers Network layer ISDN protocolsITU-T I.930 and ITU-T Q.931 defines switching and signaling methods using the D channel.
21 Network layer ISDN protocols Two Layer 3 specifications are used for ISDN signaling:ITU-T I.450 (also known as ITU-T Q.930)ITU-T I.451 (also known as ITU-T Q.931)Together, these protocols support:User-to-user circuit-switched connectionsUser-to-user packet-switched connectionsA variety of standards for:Call establishmentCall termination 
22 With Q.921/Q.931 the second digit indicates the OSI layer. NoteWith Q.921/Q.931 the second digit indicates the OSI layer.
23 ISDN Encapsulation The two most common encapsulations: PPPHDLCISDN defaults to HDLC.PPP is much more robust.Open standard specified by RFC 1661Supported by most vendors