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Switching directs network traffic in a very efficient manner - it sends information directly from the port of origin to only its destination port. Switching increases network performance, enhances flexibility and eases moves, adds and changes. Switching establishes a direct line of communication between two ports and maintains multiple simultaneous links between various ports. It proficiently manages network traffic by reducing media sharing - traffic is contained to the segment for which it is destined, be it a server, power user or workgroup.

This technology enables some key benefits over traditional Ethernet bridged and routed networks. First, a 10 Mbp or 100 Mbps shared media can be changed to dedicated bandwidth. Bridges and routers typically have many devices attached to their ports, sharing the available bandwidth. Switches enable you to connect either a shared segment (a workgroup) or a dedicated one (server) to each port. Second, this is accomplished without modifying any software or hardware already running on the workstations. Finally, a switch installation is less complex than a bridge/router configuration; this ease of use makes switching an attractive solution.

Ethernet switches segment a LAN into many parallel dedicated lines that can enable a contentionless, scalable architecture. A switch port may be configured as a segment with many stations attached to it or with a single station connected to it.

When a single LAN station is connected to a switched port it may operate in full-duplex mode. Full-duplex does not require collision detection, there is a suspension of MAC protocols. A single device resides on that port, and therefore no collisions will be encountered.

Full-duplex switching enables traffic to be sent and received simultaneously. Aggregate throughputs for 10 Mbps Ethernet networks jump to 20 Mbps, from 100 Mbps to 200 Mbps. (Hubs between a workgroup and a switch will not run full-duplex, because the hub is governed by collision detection requirements. The workgroup connected to the hub is unswitched Ethernet.)

Today the defining line between bridges and switches is fading. Switches now perform the segmentation once done by routers and bridges. Switches can do more than direct a packet to one side or the other - they send traffic directly to its destination.

ATM brings together telecoms and datacomms manufacturers who are having to agree compatibility standards for the first time. The common framework it provides will integrate the many diverse technologies which form the basis of the communications industry.

ATM is a dedicated-connection switching technology that organises digital data into 53-byte cells or packets and transmits them over a medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the line.
Because ATM is designed to be easily implemented by hardware (rather than software), faster processing speeds are possible. The prespecified bit rates are either 155.520 Mbps or 622.080 Mpbs. IEEE Spectrum reports that speeds on ATM networks are expected to reach 10 Gbps. Along with SONET and several other technologies, ATM is a key component of broadband ISDN.

The use of ATM in the LAN and WAN will offer the ultimate network which will breakdown the geographic restrictions that currently hinder networking today. User profiling will enable specific users to access a network service with no performance limitations and with their own configuration or 'feel' regardless of where they are.

The disadvantage in the foreseeable future will be the availability of the services from carriers and the cost of implementing a solely ATM network. This has led to the growth of Frame Relay as the connection method to ATM backbone networks. The technologies interoperate well and the large availability of Frame Relay services in the U.S. has forced the requirement, in fact, the majority of Frame Relay networks consist only of Frame Relay as an access method with ATM being used for the backbone network.

As we are repeatedly, the Public Switched Telephone Network (PSTN), is now 99% digital. However many of us do not realise that the telephone systems to your home or office is analogue. This is the major difference between ISDN and PSTN. When using ISDN you simply move the digital Point of Presence (POP) out to your home or office.

One of the biggest advantages of ISDN is the speed of connection. If you compare two scenarios, one with a V.34BIS modem offering 33.6Kbps and an ISDN circuit offering 64Kbps the differences are quire significant. In the first situation you are looking at a connection time of 20-30 seconds minimum. However in the situation with ISDN the call set-up time is around 1-2 seconds. There is now an emerging higher speed technology, which offers 56Kbps of throughput. More details can be found further on in this section.

There are two type of ISDN circuits that can be ordered. The first is Basic Rate Access and will give you 2x64Kbps (B-Channels) and one 16Kbps (D-Channel). This is commonly referred to as "2B+D". The presentation you are given is an RJ45 socket in your home or office. The second type of ISDN circuit is a Primary Rate Circuit. This differs from the Basic Rate by offering a range of circuits and can vary from 6-8 Channels, to 30 B-Channels. Obviously the cost of circuit rental does vary on the quantity that you have, but there are no call costs if the circuits are not used. The presentation of this service is provided by an RJ45 connection.

Quite a few people are under the misconception that you can only user ISDN for data. Admittedly the technology lends itself to data applications very well, however ISDN can be sued equally well on video and voice applications. One of the useful features of ISDN is the fact that the ISDN devices actually identify themselves to the network as to what type of device they are. Therefore if you get an incoming voice call the circuit will already know whether that call can be answered by an ISDN telephone or not.

Security concerns often arise when connecting data devices to a public network. ISDN again has a method of providing some security. This is done by using Calling Line Identification (CLI), in this situation you can actually specify what numbers you will answer, as well as what numbers you wish to connect to. This will prevent anybody having the ability to break into your data system by preventing the ISDN device from even answering the call.

It used to be that Internet users were mainly accessing email online but that has changed to people utilising the World Wide Web on a more constant basis. Email and the WWW are both different components of the Internet but use the same technology to transfer data from the computers that make up the Internet, to your computer. There are other technologies developing on a daily basis that are using the Internet as their mode of accessing information. Some of these newer technologies include video teleconferencing, real audio, Internet phone and Internet gaming.

Commerce is currently also a big part of the Internet and it is said that with the advent of the Internet, its effect on how business is done will be more far reaching than that of the industrial revolution.

As a regular user of the Internet you will most likely be using a dialup account which means that your computer will be dialing into a local access point known as a Point of Presence (PoP) of an Internet Service Provider (ISP) to gain access to information on the Internet. Once your computer has dialled into the Internet it starts thinking that it is a part of a network, which in actuality, it is. This means that you can access information that is made public on any computer also connected to the Internet, anywhere in the world.

The Internet started as a result of concerns by the U.S. Military in the late 1950's. They had computer systems set up around North America and those computer systems were linked together by a single line. If one of the computer systems were disabled it would break the link with the other computer systems and would cause a disruption in the ability for one computer to access information from another computer.

By linking their computers they were able to continue to share information and the fears surrounding loss of data due to a computer causing a break in the chain were also done away with.

Over the years other governments started to link into this network of computers and eventually research institutes and universities began to join in. It was a great benefit to someone who was doing joint research in Sao Paulo to be able to quickly send information to a co-researcher in Stockholm. The cost, both financially and to time, was set aside when scientists were able to transfer data instantaneously via the global network known as the Internet.

At this point the Internet was not of much interest to the everyday person because it was complex, difficult to use and text based. In the late eighties the idea of the WWW came into play. The WWW allowed for graphics, sounds and other forms of multimedia to be experienced on the Internet by using a graphical interface known as a Web Browser. This was based on the protocol known as Hyper Text Mark-Up Language or HTML, which allowed a user to feel they were actually 'browsing' around the world-wide network in an easy and graphical fashion by using what were know as hypertext links. A hypertext link just means that when you click on it, it will retrieve the information from that source and display it on your computer. With the advent of the WWW, the Internet became available to everyone in an easy to use fashion. There are now millions of people around the world sending each other email, browsing for information globally and having discussions and debates internationally.

V.2
Power levels for data transmission over telephone lines.
A much better bomb altogether.

V.3
International Alphabet No. 5.

V.4
General structure of signals of International Alphabet No. 5 code for data transmission over public telephone networks.

V.5
Standardisation of modulation rates and data signaling rates for synchronous data transmission in general switched network.

V.6
Ditto, on leased telephone-type circuits.

V.7
Definition of terms concerning data communications over the telephone network.

V.10
Electrical characteristics for unbalanced double-current interchange circuits for general use with integrated circuit equipment in the field of data communications.

V.11
Ditto, but for balanced double-current interchange circuits.

V.13
Answerback unit simulator.

V.15
Use of acoustic coupling for data transmission.

V.16
Recommendation for modems for transmission of medical analogue data.

V.17
14,400Kbps Fax transmission.

V.19
Modems for parallel data transmission using telephone signaling frequencies.

V.20
Parallel data transmission modems standardised for universal use in the general switched network.

V.21
300 baud modem standardised for use in the switched telephone network.

V.22
1200bps full duplex 2 wire modem standardised for use in the general switched telephone network.

V.22bis
2400bps full duplex 2 wire modem standardised for use in the general switched telephone network.

V.23
600/1200bps modem standardised for use in the general switched telephone network.

V.24
List of definitions of interchange circuits between data terminal equipment and data circuit terminating equipment (i.e. modem).

V.25
Automatic calling and/or answering equipment on the general switched telephone network.

V.25bis
Automatic calling and/or answering equipment on the general switched telephone network using the 100 series interchange circuits.

V.26
2400bps modem for use on 4 wire point-to-point circuits.

V.26bis
2400-1200bps modem standardised for use in the general switched telephone network.

V.26ter
2400bps duplex modem using the echo cancellation technique standardised for use on the general switched telephone network and on point-to-point 2 wire leased telephone type circuits.

V.27
4800bps modem for leased circuit.

V.27bis
4800/2400bps modem with automatic adaptive equaliser standardised for use on leased circuits.

V.27ter
4800/2400bps modem standardised for use in the general switched telephone network.

V.28
Electrical characteristics for unbalanced double current interchange circuits.

V. 29
9600bps modem for use on leased circuits.

V.31
Electrical characteristics for single current interchange circuits controlled by contact closure.

V.32
A family of 2 wire duplex modems operating at data signaling rates up to 9600bps for use on the general switched telephone type circuits.

V.32bis
A family of 2 wire duplex modems operating at data signaling rates up to 14400bps for use on the general switched telephone network and on 2 wire leased telephone type circuits.

V.32ter
An extension of V.32bis to include 19200bps transmission over 2 wire circuits.

V.33
14400bps modems for leased circuits.

V.34
2 wire duplex modems operating at data signaling rates up to 28800bps for use on the general switched telephone network and on 2 wire leased circuits.

V.34bis
33Kbps full duplex 2 wire modem standardised for use in the general switched telephone network.

V.35
Data transmission at 48Kbps using 60-108khz group band circuits.

V.36
Modems for synchronous data transmission using 60-180khz group band circuits.

V.37
Synchronous data transmission at a data signaling rate higher than 72Kbps using 60-108khz group band circuits.

V.40
Error indication with electromagnetic equipment.
Also: desperately unsexy Volvo!

V.41
Code independent error control system.

V.42
Error correcting technique based on LAP-M protocol.

V.42bis
Compression technique for use with V.42.

V.50
Standard limits for transmission quality of data transmission.

V.51
Organisation of the maintenance of international telephone type circuits used for data transmission.

V.52
Characteristics of distortion and error rate measuring apparatus for data transmission.

V.54
Loop test devices for modems.

V.55
Specification for an impulsive noise measuring instrument of telephone type circuits.

V.56
Comparative tests for modems for use over telephone type circuits.

V.57
Comprehensive data test set for high data signaling rates.

V.90
56Kbps full duplex 2 wire modem standardised for use in the general switched telephone network. Will probably be the world's last modem standard. (sniff!)

V.110
Equivalent to I.463.

V.120
Rate adaption standard currently in draft form only.

I.111
Relationship with other recommendations relevant to ISDN's.

I.112
Vocabulary of terms for ISDN's.

I.120
ISDN concept.

I.130
Attributes for the characteristics of telecommunications services supported by an ISDN and network capabilities of an ISDN.

I.210
Principles of telecommunication services supported by ISDN.

I.211
Bearer services supported by ISDN.

I.212
Tele-services supported by ISDN.

I.300
ISDN functional principles.

I.310
Network functional principles.

I.320
ISDN protocol reference model.

I.32X
ISDN functional architectural model.

I.325
ISDN connection types.

I.330
ISDN numbering and addressing principles.

I.331
Numbering plan for ISDN era.

I.340
ISDN connection types.

I.410
General aspects and principles relating to recommendations on ISDN user network interfaces.

I.411
ISDN user-network interfaces - reference configurations.

I.412
ISDN user-network interfaces - interface structures and access capabilities.

I.420
Basic rate user-network interface.

I.421
Primary rate user-network interface.

I.430
Basic rate user-network interface - layer 1 specification.

I.440
ISDN user-network interface data link layer - specification.

I.450
General aspects of the ISDN user-network interface layer 3 functions and protocols.

I.451
Specification of the ISDN user-network interface layer 3 protocol.

I.460
Multiplexing rate adaption and support of existing interfaces.

I.461
Support of X21 and X21bis based DTEs by an ISDN (X30).

I.462
Support of packet mode terminal equipment by an ISDN (X31).

I.463
Support of the DTEs with V-series type interfaces by an ISDN.

I.46X
Support of 56Kbps information streams on an ISDN.

I.472
Internetworking services and protocols.

G.701
Vocabulary of the digital transmission and multiplexing, and pulse code modulation (PCM) terms.

G.702
Digital hierarchy bit rates.

G.703
Physical/Electrical characteristics of hierarchical digital interfaces.

G.704
Functional characteristics of interfaces associated with network nodes.

G.705
Characteristics required to terminate digital links on a digital exchange.

G.711
Pulse code modulation (PCM) of voice frequencies.

G.712
Performance characteristics of PCM channels at audio frequencies.

G.721
32 kbps adaptive differential pulse code modulation.

G.729
8 kbps CELP modulation of voice frequencies.

G.731
Primary PCM multiplex equipment for voice frequencies.

G.732
Characteristics of primary PCM multiplex equipment operating at 2048 kbps.

G.733
Characteristics of primary PCM multiplex equipment operating at 1544 kbps

X.21
General purpose interface between data terminal equipment and data circuit terminating equipment for synchronous operation on public data networks, e.g. kilostream.

X.21 bis
General purpose interface between DTE and DCE with synchronous data. Electrically V.28 presented on a 25 way D-Type.

X.25
Interface between data terminal equipment and data circuit terminating equipment for terminals operating in the packet mode on public data networks.

X.28
DTE/DCE interface for a start/stop mode data terminal equipment accessing the packet assembly/disassembly facility (PAD) on a public data network situated in the same country.

X.29
Procedures for exchange of control information and user data between a packet mode DTE, and a packet assembly/disassembly (PAD) facility.

X.30
Rate adaption to low speed sync and async used by ISDN.

X.31
Support Packet Mode Terminal Equipment by an ISDN.

X.32
Interface between data terminal equipment and data circuit terminating equipment for terminals operating in the packet mode and accessing a packet switched public data network through a PSTN.

X.400
Networks message handling systems Series.