CIS 3260 LAN Administration
Fall 2005
Technical Research Report
Metropolitan Area Networks
Steven Gole
Signature: _______________________________
Date: 11/21/2005
Professor: Dr. Mike Tarn
Table of Contents
Abstract ......3
Introduction ... . .4
MAN . .... .4
Purpose ... ...4
Literature Review ... .7
Definitions . ..7
Functions . . ...8
Physical Medium .. . ...8
Hardware . .. .10
Technologies . .. 11
Topology . . .. .16
Standards .. . .17
Transmission Example: Pentagon .... . .18
History . .. ..19
Current Status .. . . ..21
Pros & Cons . ...23
Case Study- Project Oakland ..... ..26
Conclusions ..... .28
References .. ..29
Appendix A: Wireless Oakland Infrastructure Assets . ....... ..32
Appendix B: Wireless Oakland Participating Cities and Townships ... ......... .33
Abstract
Metropolitan Area Networks (MAN) are vital to companies, universities, the telecommunication industry, and government. MANs are composed of multiple Local Area Networks (LAN) that are linked by hardware and a physical medium in a topology. A transfer technology is needed in order data packets to travel to the correct locations. TCP/IP, SONET/SDH, ATM, DWDM, WiMAX, VoIP, SDR, and SMDS could be used as a transfer technology, as discussed.
MANs were originally standardized by AT&T and were later governed by the American Digital Hierarchy. In 1996 the government passed an act which allowed outside companies improve the national backbone with fiber-optic installation.
Project Oakland is being implemented in winter of 2005-2006 with the plan of blanking Oakland County, MI in a wireless signal. This MAN will use switching routers as hardware, and a wireless signal for propagation. TCP/IP will be used as its transfer technology.
MANs have proven to be
invaluable in connecting LANs into the global Wide Area Network.
Introduction
Metropolitan Area Networks (MAN) are an integral part of the worlds connected network. MANs are used in the corporate environment, by telecommunication providers, by learning institutions, and often by government. They are used to link distant locations and provide resource sharing and internet access to its users.
MAN
A Metropolitan Area Network (MAN) is a computer network usually spanning a city or small region. MANs link together separate Local Area Networks (LAN) from different locations in order to share resources. A logical solution for public and private networks is a MAN which will provide them with a high-speed integrated communications network that provides multiple services including data, voice, and video transfer without geographical limitations. MANs usually do not extend more than 150 kilometers, however when they reach their limit they pass their information to the Wide Area Network (WAN) to transfer it on to another segment of the MAN in a different region. (Foundry Networks, 2005)
Purpose
Networks evolved to enable sharing of resources and ideas and nowhere are the original concept of sharing more present than in MANs. Hot spots are great for a mobile individual, LANs connect a group, but MANs bring people into a community and assist them with social, educational, and corporate challenges and assignments. They have reached the mountains and islands of Scotland to bring university learning to rural students. MANs have brought the internet to villages in India which arent even reached with a proper infrastructure. In more urban areas, MANs bring civic groups together; such as government agencies across a city or state while allowing the extension of low-cost internet access to the community. Telecommunication companies use MANs to provide paying users internet and telecomm access across their medium. (Proxim, 2003)
MANs are most popular in the corporate environment and government where data security and integrity are at a premium and down time costs companies greatly. Both need to be able to communicate and share information and resources with different locations around the world. MANs make this possible.
There are three important features which discriminate MANs from LANs or WANs:
1. The network size falls intermediate between LANs and WANs. A MAN typically covers an area between 5 and 150 km diameter. Many MANs cover an area the size of a city, although in some cases MANs may be as small as a group of buildings or as large as Long Island for example. A MAN may be connected by a WAN, but the intermediate area is not part of the MAN.
2. A MAN is not generally owned by a single organization. The MAN, its communications links and equipment are generally owned by either a consortium of organizations or by a single network provider who sells the service to the users. This level of service provided to each organization must therefore be negotiated with that MAN operator, and some performance guarantees are normally specified. However, some large companies have instituted a company wide MAN.
3. A MAN often acts as a high speed network to allow sharing of regional resources It is also frequently used to provide a shared connection to other networks using a link to a WAN. Thus, a MAN is often part of a larger global WAN. (Krista, 2004)
Definitions
Access Point: A communication device for users of a wireless device to connect to a wired network.
Backbone: Main wire that connects all centralized nodes.
Broadband: A type of data transmission in which a single medium can carry several wavelengths at once.
Frame: A packet of transmitted information.
Gigabit Ethernet: A version of Ethernet that supports data rates up to one gigabit.
Hot Spot: A specific access point that provides broadband network access.
Infrastructure: The basic products, services, and installations needed for the functioning of a network.
LAN: Local Area Network: A group of linked computers that are geographically close together.
Network: A group of two or more computer systems linked together.
OSI Model: Open Systems Interconnection: An ISO Standard for worldwide communications that defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next in this order. Application, Presentation, Session, Transport, Network, Data Link, and Physical.
Packet: A piece of a message transmitted over a packet-switching network. A packet contains the destination and source address in addition to the data and sequencing information.
Protocol- A set of rules that guide a transmission between computers over a network.
Spectrum: The distribution of energy emitted by a radiant source, arranged in order of wavelengths.
Transmission: The sending of a signal, picture, or other information from a transmission source.
WAN: Wide Area Network: A group of linked computers connected over a very large geographic area.
Functions
MANs use varying technologies depending on network requirements. Physical medium, hardware, protocols, and topologies are needed to implement and manage a MAN.
Physical Medium
A physical medium is what network packets are transferred over. It operates on layer one of the OSI model.
Coaxial Cable
Inexpensive and easy to install cabling is used mostly by cable providers to connect paying broadband users to their regional MAN. Coaxial consists of a conductive core surrounded by a layer of insulation, a braided shielding, and another layer of insulation. Coaxial operates in thin and thick wire; of which thin wire is used to connect to users. Thin wire Coaxial cable transmits at 10Mbps.
CAT5/ CAT5E
This Cabling can be used in a MAN but is more often used in connecting LAN segments. It is often used with ATM and SONET/SHD. CAT5 cabling is unshielded twisted paired (UTP) or shielded twisted pair (STP) cabling. It is made of 8 wires which are intertwined and surrounded by a jacket. STP is surrounded by a metal shielding and requires grounding. CAT5 transmits at 100Mbps.
CAT6
This cabling is the recommended standard for Ethernet applications and is often used in smaller MANs. It is 8 twisted pair wires with a spline separating the wires, which is surrounded by a jacket. CAT 6 can transmit at speeds up to one gigabit. This is often the media chosen for Gigabit Ethernet.
Fiber-Optic
Fiber-Optic cabling is what is often used for MAN backbones. It sends optical light pulses through the cable. This makes it immune to interference and highly secure. Fiber Optic cable is used for high bandwidth, high speed, and long distance data transmissions. Fiber optic cabling is made of slender cylinder of glass fibers, surrounded by a layer of cladding material and then by an outer jacket. Fiber-Optic transmits at one gigabit or higher and can transmit for up to 100 kilometers without repeating. These characteristics make it the premier medium for secure MANs. (Pease, 2002)
Wireless
Wireless type of transmission is often used in MANs. Cellular/PCS systems are increasing their support of data services; there is an insatiable demand for support of higher data rates. Wireless Broadband offers an alternative for users while offering data rates of 11 Mb/s and higher. With the availability of non-line of sight (NLOS) technologies that can be installed without on-site service support, service providers are increasingly embracing wireless broadband as cost competitive bandwidth connections to users in areas not well served by cable or DSL. Wireless is often used in to prevent long and expensive cable installations between areas, or to provide multiple access points. (Krista , 2004)
Lasers
Lasers can be used on smaller networks as a transmission medium. They are a line-of-sight technology which provides optical bandwidth connections in which voice, video and data information can be sent and received simultaneously on invisible beams. They emit in an almost infrared waveband that is invisible to the unaided eye. Laser can transmit for around 1.5 miles at 1 gigabit speed. Management and environmental concerns can limit the use of lasers in certain situations. It is difficult to implement laser technologies because several different devices need to be used. Environmental problems are generally because temperature. Changing temperature variations along the optical path can cause an increased bit-error rate. (LAS, 2002)
Hardware
Hardware are the computers and machines that by using routing and switching algorithms determined correct path for network packets. These objects may aid other hardware objects.
Router
A router acts as a junction between two networks to transfer data packets among them. MANs use routers to connect two locations to the network backbone. Routers operate on layer three of the OSI model; they connect multiple network segments and filter traffic. Routers can be used to transfer information over different network architectures. They are used to select the select best path to reach the desired corresponding segment. Either a distance vector algorithm or link stat algorithm is used to find the shortest route. This is important to find the route with the least hops to prevent the network from being overloaded with traffic. In a MAN a dynamic routers are often used. These routers automatically communicate with other connected routers to share routing table and determine what LAN segments are connected to them.
Switch
A switch is a multiport segmentation device and operates at layer two of the OSI model. It reads an incoming frame and sends it out the appropriate port. Switches are used primarily in LANs but have varied use in MANs. Switches keep track of addresses in its switching table which it uses to find the correct port to pass a frame onto. Switches are often used in government MANs, where speed, reliability, and responsiveness are important, in a small area.
Repeater
A repeater is a network device that receives a signal, and then boosts its strength and fixes any corrupted bits in the packet. Repeaters are used to extend long cable runs to prevent degradation of the packet. They operate at layer one of the OSI model.
Tower
Towers and high story building buildings are used to transmit wireless signals over the scope of the MAN. Generally cellular towers that operate on a wireless broadband MAN, and can have a transmission radius of 30 miles. A line of direct sight is needed to connect to other locations including other towers. (Oakland County, 2005)
Technology
Technology consists of protocols or transfer methods in which data is handled and processed to ensure proper transfer.
Internet Protocol (IP)
The Internet Protocol (IP) is a data-oriented protocol used by source and destination hosts for communicating data across packet switched networks. The Internet Protocol provides a best effort datagram service, which makes no guarantee of delivery. The packet may arrive damaged, out of order, duplicated, or dropped entirely. If a user needs reliability and cannot afford errors, they must integrate Transmission Control Protocol (TCP). These Internet protocols are the world's most popular protocol suite because they can be used to communicate across any set of interconnected networks and are equally well suited for MAN and WAN communications. IP deals with routing and operates at layer three of the OSI model. IP is concerned with addresses and arriving at the location. TCP deals with transmission quality, while operating at layer four of the OSI model. TCP uses a three way handshake to create a stable connection in preparation of data packet transfer. (Foundry Networks, 2005)
SONET/SDH
Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) standards were developed to address the needs of a growing worldwide network. SONET (North America) and SDH (Europe) are very closely related standards and are interoperable. The SONET/SDH standards were engineered to create a highly reliable, synchronous, high-speed networking that exploits the power of fiber optic technology. SONET/SDH is highly regarded because of its predictability and ability to be easily managed. It is well designed to handle voice traffic throughout a MAN. The SONET/SDH design also features inherent weaknesses, which are revealed more clearly when large amounts of data traffic slows and burdens the network. The main weakness of SONET/SDH is the extreme high cost. (Cheng, Chen, Yu, 2005)
ATM
Asynchronous Transfer Mode (ATM) technology was introduced to enhance the SONET/SDH infrastructure and was specifically engineered to converge voice, video, and data. While ATM is used in the networking community, its use has not grown the way many thought it would. This is due primarily to the high expense associated with SONET/SDH and certain technical features of ATM that have not been as widely embraced by the marketplace. This operates by cell-relay technology that divides data units into 53-byte cells for transmission over the physical medium. (Cheng, Chen, Yu, 2005)
DWDM
Dense Wave Division Multiplexing (DWDM)
technology multiplies the amount of bandwidth that can be delivered over a
single strand of optical fiber. This is done by dividing the light in the fiber
into separate lambdas. A lambda is a separate light wavelength. This allows the
network to deliver higher amounts of bandwidth without investing in new
fiber-optic cable. Future DWDM systems are predicted to be able to handle up to
10,000 Gbps and more per fiber. (Foundry Networks, 2005)
WiMAX
WiMAX is an extension of Wi-Fi. Like Wi-Fi, it can deliver
high-speed wireless connectivity but at far greater distances; as far as 30
miles. WiMAX is said to have the potential to provide an open standard
nationwide network that will allow true interoperability between agencies in
different parts of the country. WiMAX is appealing because of its ability to
offer flexible radio performance in both licensed and unlicensed radio
spectrums. Fixed wireless or, pre-WiMAX networks are already being deployed
government services to transmit data and images in real time. WiMAX wireless
products that support increased mobility are expected to increase greatly in
2006 as more local governments are using their MANs to their advantage. The
benefit of WiMAX is the ability to blanket a large area, supplying access to all
the different services through this network instead of having a multitude of
narrowband capabilities that exists today. A challenge to overcome is the
matter of interference, which is possible in unlicensed spectrum. The increase
use of WiMAX means the interference over the radio spectrum will increase. The
Federal Communications Commission has a freed spectrum in the 800 MHz band for
public safety where interference can be avoided. (Wilson,
2005)
Voice over Internet Protocol (VoIP)
VoIP refers to the transmission of voice over a data network. VoIP
digitizes voice audio, sends it in the form of data packets over an IP network
then converts the data packet to a voice form. VolIP is often used by telephone
companies to expand their network and offer faster more reliable connection for
their networks. VoIP is valuable in an IP network architecture where efficient
or enhanced voice communications, advanced calling, or messaging features are
needed. Most major companies have VoIP capabilities, especially if they operate
on a global scale. The ability to video conference or teleconference is
enhanced with this technology. This also presents a cost efficient way to break
down a network with out using circuit switched technology. VoIP is attractive
in government for Emergency-911 because it could be used as to provide
near-instantaneous transmission of voice and data over a single connection.
There are concerns such as securing the system from public or internal threats.
The US Commerce Department switched to a VoIP network after the agency's
emergency system failed because of the Sept. 11 attacks. Now, if an emergency
were threatening anyone over the MAN, one would be able to hear a voice response
to a possible threat. (Passmore, 2005)
Software Defined Radio
Software defined radio (SDR) is a potential breakthrough in network
interoperability. SDR allows one to log into a server and download software that
connects to everyone with the same software. In order to communicate with a
different network, a user would need to download the needed software, and they
could have a secure, connection. It also means that with higher layer
software, one can patch together different radio systems so that users can
connect to each other directly. This is a new way to bring different LANs into
one MAN. With this one can create a new infrastructure when needed. The
creation of a database of all the different radios in the region is needed. So
that based on what user is downloading the program, one can launch the relevant
radio systems and communicate dynamically with the needed user. High Cost and
lack of understanding, standards, and guidance are a major reason why this
technology is not used more often. A lot of administrators making buying
decisions for this kind of technology want guidance from the federal government
or IEEE before they invest in it. This is an easy way to manage a MAN with
varying users and security levels. (Passmore, 2005)
SMDS
Switched Multimega-bit Data Services (SMDS), a high-speed switched data communication service offered by telephone companies that enable organizations to connect geographically separate LANs into a single MAN. Prior to SMDS's invention in 1995, the only way to connect LANs was through a dedicated private line. This is still the way most MANs are connected, but SMDS is becoming an increasingly attractive alternative because it is more flexible and more economical. It can use a variety of technologies but is limited in speed at 45mbps transfer rate required by phone lines. The development of this service has paralleled the emerging ATM standards. SMDS is considered to be an intermediate between the packet-switched services and the ATM service. (SMDS, 2002)
Topologies
A topology is the physical layout and how the network is mapped. It also shows what hardware is implemented.
Mesh Networks
Mesh networks multi-hop systems that process messages by passing
data packets from device to device until they reach its destination point. There
is no central device, however each device is interconnected. Each device adds to
the network coverage, extending the network. Mesh networks offer higher
bandwidth, improved reliability and large area of coverage, and is a topology
that could allow interoperable networks. Mesh networks are important in
government, especially in the emergency environment. The ability to gain access
from any point, especially if it operates wirelessly is invaluable. Because it
is a mesh topology there is very little chance of a network point being
inoperable because it is connected to all other areas. The multiple nodes in a
mesh network provide reliability because if one node fails, there are many more
available to pass on a data packet. Functionality begins to decline when a
large-scale network is needed, such as a statewide system. Cost would be
extraordinarily high and management would be far too difficult.
A network that utilizes a wireless medium has a wireless topology. Generally a user can access the internet or network from any access point inside the networks broadcast radius. Security is a major problem with wireless as it is an open access to hackers. Bandwidth may also be consumed by others that are leeching off the signal. To prevent unwanted wireless access administrators use MAC filtering. This is configuring an access location to only allow certain MAC addresses to access the network. Another solution is to use software such as Cisco Wireless Security. This provides an intrusion prevention system, high level of data encryption, real time management of threats, and security policy that applies to all users.
Linked Via Backbone
In smaller MANs a backbone is used to link the different LANS together. Generally it is used to link two to four LANs over a smaller area. Normally Fiber-optic cabling is used because of its fast transfer speed and ability for long cable runs.
Standards
Standards formulated by the Institute for Electrical and Electronic Engineer (IEEE) are related to computer industry and other electronic facets.
IEEE 802.1 LAN/MAN Bridging and Management
This is the standards for MAN media access control and discovery. This entails each machines MAC, bridges, and routers.
IEEE 802.2 Logical Link Control
Standard for Information technology & Telecommunications information exchange between systems two systems. This includes between LANs and MANs. (IEEE, 2005)
IEEE 802.3 CSMA/CD
Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications are detailed with this standard. (IEEE, 2005)
IEEE 802.11 Wireless LANs
This standard defines the media access control and physical medium for a LAN with wireless connectivity. It addresses local area networking where the connected devices communicate over the air to other devices that are within close proximity to each other. (IEEE, 2005)
IEEE 802.12 Demand Priority Access Method
Standards 802.12 are for the exchange of packets between two systems in a MAN. This also includes demand priority access for which request is attended to first and physical layer and repeater specifications for 100mb/s operations. (IEEE, 2005)
IEEE 802.16 Broadband Wireless MAN
The IEEE 802.16 defines wireless service that provides a communications path between a subscriber site and a core network such as the public telephone network and the Internet. The Wireless MAN technology is also concerning WiMAX. The WiMAX, wireless broadband access standard provides the missing link for the "last mile" connection in metropolitan area networks where DSL, Cable and other broadband access methods are not available or too expensive. (IEEE, 2005)
Transmission Example: Pentagon
If a government user in New York (NY) needs information off a Pentagon server in Washington they need to access the government MAN. The defense information systems network operates a TCP/IP routed network. (Pike, 2000) First, the NY user will have to contact the server by sending out a packet, once contact is made the server will respond and the TCP three way handshakes begins. Once a secure connection is made then data may be transferred from the server to the user in NY.
The transmission leaves the NY users LAN and is transmitted by an IP router across the Pentagons fiber-optic MAN infrastructure. After several hops the packet will reach the correct router which will route the packet towards the server. Likely the packet will encounter several other routers inside the server building. Once connected to the server it will reversely send the information back across the fiber optic cabling. The Pentagon currently operates with a linked dedicated backbone which will allow connection to different locations.
The standards used in this transmission are under IEEE 802b (amended version). 802.1 used in the first step, media access control connectivity and discovery. Standard 802.2 is used for each systems logical link control. Throughout the packet transfer 802.3 is used for CSMA/CD. Being connected to a server, Standard 802.12 is used for the telecommunication and information exchange between two systems. (Pike, 2000)
A message, medium, hardware, technologies, and the standards that govern them are needed to make this transmission over the Pentagon MAN a success.
History
For many years LANs dominated corporate and government. Through the spread of large business and the knowledge that government needed to share forged the way for MANs. For many years, the standards for running the collection of networks that make up MANs and WANs was determined by AT&T Corp. This was because they owned the majority of telephony infrastructure. The North American Digital Hierarchy next, designed standards to handle voice traffic, was developed in the late 1950s and forms the groundwork foundation of much of the US MAN infrastructure today. A similar situation exists internationally. Over the past two decades, these circuit-switched networks controlled by telephone companies have been enhanced by new technologies including SONET/SDH and ATM.
Modern networks are moving away from these traditional circuit-switched networking technologies, which are tuned primarily for voice traffic, towards packet-switched networking technologies, which are built for the convergence of data, video and voice. The advent of technologies including Gigabit Ethernet, IP, DWDM, and WiMAX are combining to usher in a new era of MAN networks.
As of 1990, the worldwide network was still dominated by a relatively small number of carriers that maintained a great deal of control over technology and standards development. In the US, the Telecommunications Act of 1996, passed by Congress, began to change and shape the industry. This Act required existing carriers in the U.S. to open their networks to other service providers and new carriers so that they could get access to end users. This prevented a monopoly on the industry which was posed by the superpower telecommunication companies. Most significantly, it also required municipalities to allow new carriers to dig up their streets and property to lay their own fiber optic cables. This resulted in a massive build out of the U.S. fiber-optic infrastructure in a very short period of time. This vastly improved the ablility and quality of present day MANs. Todays MANs can afford to use varied technologies that suit their administrators needs. Because of the convergence over the past 55 years, todays technologies are present and able to operate in variety across the MAN landscape. (Marson, 2005)
Current Status
The needs for MANs are constantly increasing. Currently, telecom carriers predominately use SONET/SDH technology to merge data traffic in the MAN network before accessing the Internet backbone. Because of the limitations of SONET/SDH technology in transporting data traffic, especially in terms of bandwidth and efficiency, there is a need to find a broadband access solution. The emergence of Gigabit Ethernet technology provides benefits that the SONET/SDH equipment lacks. However, Gigabit Ethernet also presents shortcomings. However, the use of an increasing fiber optic infrastructure is vital in the present day MAN.
With locations across the country, linking together separate LANs into a MAN can pose logistical problems. Since companies can lease telecommunication or fiber lines costs and speeds can be differentiated for the administrators needs. Along with leased lines; wireless, lasers, and optical medium is used to transmit signals. With the varied mediums available and many different transfer technologies administrators can develop varied networks based on their needs. Also because of the varied technological landscape, it has become far less expensive to deploy networks, allowing many more entities the ability to do so. Several companies such as Foundry Networks and Riverstone Networks have made a business of implementing MANs for companies. These types of companies set up, and administer a MAN.
MANs are firmly implanted in North America, Europe, and for the most part Asia. However in the late 1990s, Latin American companies are beginning to establish their own MANs. Costa Rica in 1997 implemented a MAN that will link government and academic stations as well as provide internet access. Because of a poorly wired infrastructure many Latin governments and companies are using satellite or wireless mediums to connect to locations. Costa Rica is also vital in implementing a Central American backbone. This backbone links all seven Central American countries in an effort to further integrate economies.
MANs have created new technologies, new industries and powered corporate information sharing. These practices have started to be promoted in Latin America and have proven to link several companies and countries.
Pros & Cons
There are numerous advantages to a MAN, and very few negative aspects.
Pros
There are numerous advantages to implementing a MAN. Increased resource sharing is the main reason for a linking LANs. To be able to instantaneously share information, programs, and provide an increased source of communication is immeasurable in organizations today. An example of this is work grouping, which is when a team in two or more locations can work on a process concurrently. They are instantaneously sharing information, processing programs and operating under increased communication. This increases productivity, quality, and saves the organization capital. Most MANs implement a data collection point. This provides another source of data back up incase of a disaster. Springfield, MO implemented a MAN that local businesses and citizens could access. As a result of the MAN rollout productivity improved 2.5 times at 1/3 the cost. They are now implementing a data collection facility, located 85 feet underground which will backup vital information. This has shown to decrease large business insurance costs for the area.
The speed of file transfer is fast in a MAN compared to other methods, thus there is a great deal of time saved. There would be a few minutes delay for another travel format. Multiply that delay across a company results in a great decrease in productivity and a loss of capital.
Overall a MAN can save a company capital by further using application servers across the network. By having application servers the ability to load programs on all computers on the MAN, a great deal in licensing capital will be saving. If this were able for all programs in use there would be a significant decrease in the amount spent on application software. By using VoIP better communication can be established, which will allow users to better accomplish a task with out the need for an actual meeting. A MAN can interface the meeting while saving the company capital and productivity time.
Cons
Negative aspects to a MAN generally occur with high cost and decreased security.
It is far more expensive to establish a MAN than having separate LANs. Organizations need to invest in a dedicated medium, new hardware, and increased human support and knowledge. MAN pricing tools let administrators price several network situations to compare needs to a budget. Cost is determined by needs of the organization and can often cost tens of thousands of dollars depending on size. With a larger network it is inherent that it becomes more difficult to manage, resulting in the need for highly trained professionals to manage it.
The
second major concern is security. With a larger ability access to information
on a MAN there is a larger risk of a security risk. Having a larger network
opens more doors for hackers to access and violate network policies. With
increased size there is a need for increased security. Another security concern
is viruses, trojans, worms, and hybrids. These programs will gain access to a
network node and through malicious code, attempt to disrupt and destroy a users
computers and the network itself. The correct device, network, and service
protection are needed to help prevent problems and downtime.
ASIC based switching and
routing is used in all layer two and three devices. This applies a network
policy to each packet which provides the best routes for all packets that have
the same related information. Network protection is given by the type of
topology used. A high fault tolerance topology such as mesh will provide the
network that can best withstand and prevent an attack. Service protection can
be performed by network analysts and administrators by using software and by
recognizing problems. Software such as sFlow
traffic monitoring, StealthWatch,
and Firewalls has been implemented on MANs. Though there are solutions to
cons, they still exist and can greatly affect how a MAN is implemented and how
it operates.
CASE STUDY- Project
Oakland
Case Analysis
The goal of Project Oakland is to cover Oakland County, Michigan with a wireless blanket of internet. Oakland Co is comprised of 910 square miles with a user population of 1.2 Million. 34 cities or townships have agreed to provide wireless access to their residents. This project is funded by private companies, and will be maintained by them. (Oakland County, 2005) There will be two internet services available, a free service and a pay service. The free service will operate at 128K, while the pay service will operate at high bandwidth levels. Oakland Co has chosen MichTel Corp. to implement the wireless MAN. They have the use of the countys fiber-optic network, 143 towers, 675 buildings and structures, and 1600 traffic and tornado siren poles. These assets are will be used to house wireless equipment and for use in the network. (Oakland County, 2005)
Implementation
MichTel will be installing many BelAir 200 wireless switch routers. The BelAir200 is a four-radio, wireless internetworking platform that can be used to build large-scale Wi-Fi networks from single, private buildings or towers. Some designated buildings will be penetrated with a signal. MichTel will use the BelAir 100 switch router which is a two-radio, wireless internetworking platform that can be used in smaller areas and in buildings. They will use the fiber-optic network for backhaul. Internet service will be fed through the fiber-optic cable and dispersed to disclosed aggregate sites and through line of sight towers. TCP/IP protocol will be used as only internet access will be provided. BelAir Network Management Software will be used to manage and provide security to the network. This system is designed to work with BelAir switching and routing products. Other security measures will be implemented; however, they have not been disclosed. (Oakland County, 2005)
The wireless devices and infrastructure will be implemented in the winter of 2006-2007. Users will be able to access the wireless services by having a computer with an installed Wi-Fi card. (Oakland County, 2005)
Advantage of MAN
Oakland County will have several advantages in implementing Project Oakland. The major advantage is breaking down the technological divide in the county and offers all residents the ability to procure free internet access. This also enhances the countys ability to gain and retain high-tech and nanotechnology business, while supporting a growing mobile workforce. Project Oakland provides a medium for which government can inform the public of important information. At zero cost to residents there are several major advantages to Project Oakland. (Oakland County, 2005)
Note: Refer to appendix A & B for infrastructure map and map of participating cities and townships.
Conclusion
Metropolitan Area Networks are a vital supplier of resource sharing for many governments and corporations. A MAN needs a physical medium, hardware, transfer technologies, and an implemented topology to function. There are several noted mediums, of which fiber-optic and wireless are most used. Hardware required are routers, switches, or a combination of devices. Towers and repeaters are often used when needed. There are several technologies available, and can be implemented to solve several needs. TCP/IP is most often used as shown with Project Oakland. However, a combination of other technologies can be implemented such as, SONET/SDH, ATM, DWDM, WiMAX, VoIP, SDR, or SMDS. Topologies used are often a mesh multi-hop network or a wireless. However, smaller MANs use a linked backbone topology. The IEEE 802 standards are used to govern aspects of a MAN.
MANs were originally governed by AT&T, but through the 1950s the North American Digital Hierarchy determined standards. In 1996 a government act was passed which greatly enhanced MANs capability by allowing the implementation of new fiber-optic cabling. Fiber-optic still has a strong hold on the industry, and coupled with gigabit Ethernet the ability of MANs have been greatly enhanced.
Project Oakland is an example of a MAN which will provide internet access to the majority of the county. With the use of wireless signal from BelAir switch routes they can propagate a signal over 910 square miles.
MANs have proven to be invaluable in government, the corporate sector, and the telecommunication industry.
References
BelAir Networks. (2005, November). Wireless Mesh from BelAir Networks. Available: http://www.belairnetworks.com/index.cfm
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Appendix: A : Wireless Oakland Infrastructure Assets
(Oakland
County, 2005)
Appendix B: Wireless Oakland Participating Cities and Townships
(Oakland County, 2005)