For example, if the purpose is to provide a nearby branch with high-speed secure services, a private dedicated or switched connection may be best. If the purpose is to connect many remote offices, a public WAN using the Internet may be the best choice. For distributed operations, a combination of options may be the solution. For a private WAN, should it be dedicated or switched? Real-time, high-volume transactions have special requirements that could favor a dedicated line, such as traffic flowing between the data center and the corporate head office.
If the enterprise is connecting to a local single branch, a dedicated leased line could be used. However, that option would become very expensive for a WAN connecting multiple offices. In that case, a switched connection might be better. To connect teleworkers or customers, remote-access VPNs are a better option. If the WAN is serving a mixture of remote offices, teleworkers, and authorized customers, such as a global company with distributed operations, a combination of VPN options may be required.
Which connection options are available locally? In some areas, not all WAN connection options are available. In this case, the selection process is simplified, although the resulting WAN may provide less than optimal performance.
For example, in a rural or remote area, the only option may be VSAT or cellular access. What is the cost of the available connection options? Depending on the option chosen, the WAN can be a significant ongoing expense. The cost of a particular option must be weighed against how well it meets the other requirements. For example, a dedicated leased line is the most expensive option, but the expense may be justified if it is critical to ensure secure transmission of high volumes of real-time data.
For less demanding applications, a less expensive switched or Internet connection option may be more suitable. Using the preceding guidelines, as well as those described by the Cisco Enterprise Architecture, a network administrator should be able to choose an appropriate WAN connection to meet the requirements of different business scenarios. I would like to receive exclusive offers and hear about products from Cisco Press and its family of brands. I can unsubscribe at any time. Pearson Education, Inc.
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All rights reserved. Cisco Press. Join Sign In. Date: Nov 30, Contents Objectives Key Terms Introduction 1. Selecting a WAN Technology 1. WAN Services 1. NOTE Although very few enterprises support dialup access, it is still a viable solution for remote areas with limited WAN access options. NOTE Although ISDN is still an important technology for telephone service provider networks, it has declined in popularity as an Internet connection option with the introduction of high-speed DSL and other broadband services.
Summary 1. Overview Pearson Education, Inc. Collection and Use of Information To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including: Questions and Inquiries For inquiries and questions, we collect the inquiry or question, together with name, contact details email address, phone number and mailing address and any other additional information voluntarily submitted to us through a Contact Us form or an email.
Surveys Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Contests and Drawings Occasionally, we may sponsor a contest or drawing. Newsletters If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information ciscopress.
Service Announcements On rare occasions it is necessary to send out a strictly service related announcement. Customer Service We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.
Other Collection and Use of Information Application and System Logs Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Web Analytics Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. Cookies and Related Technologies This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising.
Security Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure. An ISDN connection consists of several different types of digital channel. The 64 Kb B-channel used for transferring data, and the D-channel used for transmitting control information are the most common type of channels in use. Some remote access servers support a feature called multilink allowing the two B-channels to be combined in a single virtual link of Kbps.
In reality, often 1 B-channel is used for data an Internet connection for example and 1 B-channel is used for voice connected to a digital telephone for example. A T1 connection is a digital leased line made up of 24 channels called DS0, 1 DS0 is 64K that providing transfer rates up to 1. The European version E1 is made up of 30 channels providing rates up to 2. The Japanese version is made up of 24 channels just like a T1. A T3 is an even faster digital leased line providing rates up to The European version E3 provides rates up to T3, E3, and J3 use the DS3 signaling standard.
Sonet Synchronous Optical NETwork is a hierarchy of standardized digital data rates for optical transmission interfaces proposed by Bellcore. The data rates in these fiber optic networks are divided in OC-levels. The following table lists the speeds for all OC levels:. Because the older telephone lines were prone to error and interference, X. The main part of an X.
ATM is short for Asynchronous Transfer Mode , a packet-switching network that is commonly used for high-speed backbones in large network environments such as the Internet, for voice, data and video transfer.
Data is transmitted in small byte fixed length cells , and that is why ATM is also referred to as a cell-switching network. Partly because of the fixed length cell approach, ATM is able to reach data rates up to Mbps. Also, an ATM switch uses integrated hardware circuits that switch cells between incoming and outgoing ports which significantly increase data throughput compared to software based switching. Every cell with the same source and destination address travels over the same route if possible.
The latter allows data to be prioritized based on the content. For example, real-time video transfer could have a higher priority than file transfer, to allow the user to watch the video without interruptions. An advantage of using Frame Relay is that the physical network medium and the available bandwidth are dynamically shared between the connected end nodes.
Frame Relay can be very cost-effective because generally you often only pay for the bandwidth usage. They build large networks that span entire cities or regions and lease the right to use their networks to their customers.
On the LAN, the dominant protocol that we use is Ethernet. For wide area networks, there are dozens of technologies and protocols we can choose from. On the physical layer, we use different hardware, cables, connectors and interfaces. On the data link layer, there are a number of different WAN protocols that we can use. When you read about WAN technologies and protocols, there is a lot of terminology you might encounter.
The picture above is what a WAN solution in general looks like. Let me walk you through the different items in the picture:. The phone network used telephone switchboards that were operated by switchboard operators who connected calls by plugging in phone plugs in the required phone jacks.
To connect long distance calls, operators had to work together with operators in other offices. Once the correct plugs were connected, a circuit was established between two callers which allowed them to talk to each other.
Above we have four users, the cloud is the phone network with two switchboards. The operators would plug in the required phone plugs to establish a circuit like this:. The circuit that is established is used exclusively by user 1 and user 3.
User 2 and user 4 would also like to talk to each other. After connecting the right phone plugs, the circuit is established:. What if we had a fifth user? The fifth user has to wait since there is no available capacity in our network. We will have to wait until one of the calls is completed so the circuit can be disconnected. The example above explains the limitations of circuit switching. Once the circuit is established, the capacity is reserved for that circuit.
The problem with circuit switching is the limited capacity that it offers. Once the circuit is established, you make a reservation in the network and you end up with a fixed capacity for the circuit.
This also means that you waste a lot of unused resources…. Each chunk is a packet that is sent on the network. This is what we mostly use on our networks nowadays. Above you can see that host 2 wants to send bytes of data. This is broken down in 3x byte packets.
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