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Lesson 2 Networking
Objective This page asks you to describe LANs

Local Area Networks

Large area networks (LAN's) enable computing devices within the same local area, such as the same building or physical structure, to share information. Most LANs do not require use of common telecommunications carriers. Given their limited reach in terms of physical distance, most LAN wiring is done either internally by organizations or by local wiring contractors.
  • LAN Considerations: Usually e-Commerce architects don't have to worry about LANs and the majority of organizations have already installed them. They have interconnected their LANs to a wide area network (WAN), and the WAN to the Internet.
  • Legacy Networking Operating Systems: Server operating systems that supply basic services for LANs include:
    1. Novell's Netware
    2. Microsoft's Windows 2003/ 2008/2012/2016
    3. Sun's Solaris (now Oracle)
  • Networking Operating System: A computer operating system referred to as Networking Operating System was designed with the sole purpose of supporting workstations, database, application, file and printer access sharing between multiple computers in a network. It is also referred to as NOS basically a software that, makes it possible for multiple computers to communicate, connect hardware devices and share files with each other and in and, in some instances, older terminals that are connected on a local area network (LAN). This operating system includes special functions that help in connecting devices and computers to a local-area network and internetwork. Typically the composition of a network operating system would be a compilation of a number of personal computers along with a common printer, server and file server for archival storage, with a local network that ties them all together. There are certain standalone operating systems, like Microsoft Windows NT and Digital' s OpenVMS, which come with multipurpose capabilities and can also act as network operating systems. Although these are some of the most popular network operating systems- Microsoft Windows Server 2003, Microsoft Windows Server 2008, Linux and Mac OS X.

Server Operating Systems

These server operating systems are the most popular for LANs. However, practically every operating system (OS) that runs on small- and medium-size server hardware either possesses a LAN implementation, or there are third party LAN products that run on the server operating system.
Warning: Keep in mind there are a few confusing variations. For example, there is Netware for Windows. This is the organization using Novell's Netware as the LAN operating system, running on top of NT, which is used as the server (but not LAN!) operating system. In order for computers to operate on LANs, they usually need what is known as a Network Interface Card, or NIC. Leading NIC vendors include 3COM and Intel, but there are plenty of other dependable suppliers, like Zoom Telephonics, Adapec, and Belkin. Most LANs need repeaters, a signal strengthening network product.
New companies or locations, however, will need LAN installation. Remember most ecommerce solutions that involve internal corporate users will usually traverse over LANs. LANs must be considered as an element in the solution.


LAN Standards

By far, most commercial LANs are based on the Ethernet LAN specification. Ethernet LANs typically come in two speeds, 10 megabits per second, and increasingly 100 megabits per second (so-called "Fast Ethernet"). Token ring is also a major LAN specification standard, though it trails Ethernet by an extremely wide margin. Typically, only the "bluest" of corporations, that is, corporations with a strict allegiance to IBM, still use Token Ring[1]. 
Standard
Data Rate 
Modulation Scheme
Security
Pros/Cons & More Info
IEEE 802.11
Up to 2Mbps in the 2.4GHz band FHSS or DSSS WEP & WPA This specification has been extended into 802.11b.
  • IEEE 802.11a: (Wi-Fi) Up to 54Mbps in the 5GHz band OFDM WEP & WPA Products that adhere to this standard are considered "Wi-Fi Certified." Eight available channels.
    Less potential for RF interference than 802.11b and 802.11g. Better than 802.11b at supporting multimedia voice, video and large-image applications in densely populated user environments. Relatively shorter range than 802.11b. Not interoperable with 802.11b.
  • IEEE 802.11b: (Wi-Fi) Up to 11Mbps in the 2.4GHz band DSSS with CCK WEP & WPA Products that adhere to this standard are considered Wi-Fi Certified. Not interoperable with 802.11a. Requires fewer access points than 802.11a for coverage of large areas. Offers high-speed access to data at up to 300 feet from base station. 14 channels available in the 2.4GHz band (only 11 of which can be used in the U.S. due to FCC regulations) with only three non-overlapping channels.
  • IEEE 802.11g: (Wi-Fi) Up to 54Mbps in the 2.4GHz band OFDM above 20Mbps, DSSS with CCK below 20Mbps WEP & WPA Products that adhere to this standard are considered "Wi-Fi Certified." May replace 802.11b. Improved security enhancements over 802.11. Compatible with 802.11b. 14 channels available in the 2.4GHz band (only 11 of which can be used in the U.S. due to FCC regulations) with only three non-overlapping channels.
  • IEEE 802.16:(WiMAX) Specifies WiMAX in the 10 to 66 GHz range OFDM DES3 and AES Commonly referred to as WiMAX or less commonly as Wireless MAN or the Air Interface Standard, IEEE 802.16 is a specification for fixed broadband wireless metropolitan access networks (MANs)
  • IEEE - 802.16a (WiMAX) Added support for the 2 to 11 GHz range. OFDM, DES3 and AES, commonly referred to as WiMAX or less commonly as WirelessMAN or the Air Interface Standard, IEEE 802.16 is a specification for fixed broadband wireless metropolitan access networks (MANs)
    Bluetooth: Up to 2Mbps in the 2.45GHz band FHSS PPTP, SSL or VPN No native support for IP, so it does not support TCP/IP and wireless LAN applications well. Not originally created to support wireless LANs. Best suited for connecting PDAs, cell phones and PCs in short intervals.
    1. HomeRF: Up to 10Mbps in the 2.4GHZ band FHSS Independent network IP addresses for each network. Data is sent with a 56-bit encryption algorithm. Note: HomeRF is no longer being supported by any vendors or working groups. Intended for use in homes, not enterprises. Range is only 150 feet from base station. Relatively inexpensive to set up and maintain. Voice quality is always good because it continuously reserves a chunk of bandwidth for voice services. Responds well to interference because of frequency-hopping modulation.
    2. HiperLAN/1 (Europe): Up to 20Mbps in the 5GHz band CSMA/CA Per-session encryption and individual authentication. Only in Europe. HiperLAN is totally ad-hoc, requiring no configuration and no central controller. Doesn't provide real isochronous services. Relatively expensive to operate and maintain. No guarantee of bandwidth.
    3. HiperLAN/2 (Europe): Up to 54Mbps in the 5GHz band OFDM Strong security features with support for individual authentication and per-session encryption keys. Only in Europe. Designed to carry ATM cells, IP packets, Firewire packets (IEEE 1394) and digital voice (from cellular phones). Better quality of service than HiperLAN/1 and guarantees bandwidth.
    4. OpenAir: Pre-802.11 protocol, using Frequency Hopping and 0.8 and 1.6 Mb/s bit rate CSMA/CA with MAC retransmissions OpenAir doesn't implement any encryption at the MAC layer, but generates Network ID based on a password (Security ID) OpenAir is the proprietary protocol from Proxim. All OpenAir products are based on Proxim's module.

Bandwidth Problems

Consider the possible role of LANs in bandwidth problems.
Often slow response signals a network bandwidth problem, and technically LANs are part of the network. Many companies take their LANs for granted and don't always do the performance tuning required to keep their LANs operating at peak efficiency. When trying to solve a bandwidth problem for e-Commerce solutions that involve internal users, don't forget to check the LAN. It could be the source of your bottleneck. In e-Commerce solutions bandwidth is not always the issue. Sometimes, server processing is slow, especially where there are distributed transactions occurring in the background.

Verify your understanding of the concepts we have covered with a Project Planning - Quiz.
This quiz will provide you with valuable practice prior to taking the end of course test.
Project Planning - Quiz

[1] Token Ring:A type of computer network in which all the computers are schematically arranged in a circle.

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