WideAreaNetworks Beth McKinney

Dial Up T Carrier Switched Circuit Packet Wide Area Network This tutorial will define and discuss various aspects of Wide Area Networks (WANs) then provide a transportation analogy to help the learner relate the new information with prior knowledge. ↔

Dial Up T Carrier Switched Circuit Packet Wide Area Network A WAN spans a large geographic area. WANs often connect multiple smaller networks, such as local area networks (LANs) or metro area networks (MANs). The world's most popular WAN is the Internet.

Dial Up T Carrier Switched Circuit PacketDial-up A dial-up line is a temporary connection that uses one or more phone lines for communication. Dial-up is the slowest most frustrating method of connecting to the internet because the public telephone network usually limits transmission speeds to about 33.6 Kbps.

Dial Up T Carrier Switched Circuit PacketDial-up Traditional phone lines transmit analog signals while computers use digital signals. A device is needed to change digital to analog (modulate) and analog to digital (demodulate). This device is called a modem.

Dial Up T Carrier Switched Circuit Packet Dial-up Networks /pre-interstate_map_of_us_routes_and_highways_1955.jpg like early roads before Interstates… SLOW but still useful when there is no other alternative

Dial Up T Carrier Switched Circuit PacketT-carrier Four types of T-carrier lines available in US T1 lines offer transmission speeds of 1.544Mbps, and they can create point-to-point dedicated digital communication paths. T1 lines have commonly been used for connecting LANs. (copper) T2 leased lines offer transmission speeds of 6.312Mbps. (copper) T3 lines offer transmission speeds of up to Mbps. (fiber optic) T4 lines offer impressive transmission speeds of up to Mbps. (fiber optic) T-carrier lines are high-speed dedicated digital lines that can be leased from telephone companies. T-carrier lines can support both voice and data transmissions and are often used to create point-to-point private networks. Because they are a dedicated link, they can be a costly WAN option. T1 & T3 are most common.

Dial Up T Carrier Switched Circuit PacketT-carrier like toll roads… they are quick with less traffic but it will cost you

Dial Up T Carrier Switched Circuit Packet Switched Networks Hub - each vehicle is data waiting for an opportunity to continue on its trip. Think of a hub as an intersection where everyone has to stop. If more than one car reaches the intersection at the same time, they have to wait for their turn to proceed. Instead of two roads, imagine how hundreds of roads coming together at an intersection would effect the amount of waiting and the potential for a collision. Switch – what if the data could take an exit ramp from any one of those roads to any road of choice? That is exactly what a switch does for network traffic. A switch is like a cloverleaf intersection -- each car can take an exit ramp to get to its destination without having to stop and wait for other traffic to go by.

Dial Up T Carrier Switched Circuit Packet Switched Networks Not all roads/intersections need off ramps. Some roads do not have that much traffic where an off ramp is not necessary and would possibly cause unnecessary traffic problems. Similarly, networks only need switches at intersections with high traffic. Just like our highway system, there are intersections on a network where a hub (stop sign) is the best choice. There are also intersections where moderate traffic requires a small switch (traffic signal) or a great deal of traffic that needs to travel quickly through many large switches (off ramp system, “clover leaf”).

Dial Up T Carrier Switched Circuit Packet Circuit Switching circuit switching requires a dedicated physical connection between the sending and receiving devices sending system establishes a physical connection, the data is transmitted between the two, and when the transmission is complete, the channel is closed advantage is that after a connection is established, there is a consistent and reliable connection between the sending and receiving device allows for transmissions at a guaranteed rate of transfer

Dial Up T Carrier Switched Circuit Packet Circuit Switching (DSL) Internet access method that uses a standard phone line to provide high-speed Internet access a different frequency can be used for digital and analog signals, which means that you can talk on the phone while you're uploading data Although there have been many types of DSL since it was created in the late 1990s, the two most common are: ◦ Asymmetric DSL (ADSL) Probably the most common of the DSL varieties is ADSL. With ADSL, downloads are faster than uploads. ◦ Symmetric DSL (SDSL) SDSL offers the same speeds for uploads and for downloads, making it most suitable for business applications such as Web hosting, intranets, and e-commerce.

Dial Up T Carrier Switched Circuit Packet Circuit Switching (DSL) Similar to passenger rail transportation... although effective, the lines are dedicated and it takes many lines running simultaneously to be highly effective

Dial Up T Carrier Switched Circuit Packet Circuit Switching (ISDN) considerably faster than regular modem connections (special line with expensive monthly subscription required) dial the number associated with the receiving computer just like a conventional phone call or modem dial-up connection line pickup is very fast, allowing a connection to be established, or brought up, much more quickly than a conventional phone line most often used for high quality live videoconferencing

Dial Up T Carrier Switched Circuit Packet Circuit Switching (ISDN) similar to high speed railways… dedicated lines that are fast, efficient, and expensive

Dial Up T Carrier Switched Circuit Packet Packet Switching data transfer messages are broken down into smaller pieces called packets each packet is assigned source, destination, and intermediate node addresses packets are required to have this information because they travel different paths independent routing is one of the advantages of packet switching (selects fastest routes, can avoid unavailable routes) packets received out of order then sequenced at destination packet loss is a disadvantage

Dial Up T Carrier Switched Circuit Packet Packet Switching Like traveling to an away ballgame… everyone starts in basically the same place, then they load into their own vehicles to get to the destination as quickly as possible using whatever route they choose. Once at their destination they congregate back together for the intended purpose

Dial Up T Carrier Switched Circuit Packet Wide Area Network What type of network do you connect to at home? What type of network do you connect to at work?

Dial Up T Carrier Switched Circuit Packet Wide Area Network There are many types of wide area networks available. This tutorial explains the most prevalent types and the a few of the most utilized methods of data transport in use today. I wonder what tomorrow will bring?