information systems

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About network topology

Task: 1

Network Topology:

Network topology is the study of the arrangement or mapping of the elements (links, nodes, etc.) of a network, especially the physical (real) and logical (virtual) interconnections between nodes. A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN will have one or more links to one or more other nodes in the network and the mapping of these links and nodes onto a graph results in a geometrical shape that determines the physical topology of the network.

Types of Network Topology:

The arrangement or mapping of the elements of a network gives rise to certain basic topologies which may then be combined to form more complex topologies (hybrid topologies). The most common of these basic types of topologies are:

  • Star Topology.
  • Bus Topology.
  • Ring Topology.
  • Mesh Topology.

Star Topology:

Advantages and Disadvantages of Star Topology:

Advantages:

  • Batter performance.
  • Isolation of devices
  • Benefits from centralization

Disadvantages of Star Topology:

  • The high dependence of the system on the functioning of the central switch
  • The performance and scalability of the network depend of the switch.

Bus Topology:

Advantages and Disadvantages of Bus Network:

Advantages:

  • Easy to implement and extend
  • Requires less cable length than a star topology
  • Cheaper than other topologies.

Disadvantages:

  • Limited cable length and number of stations.
  • If there is a problem with the cable, the entire network goes down.
  • Maintenance costs may be higher in the long run.

Ring Topology:

Advantages

  • Very orderly network where every device has access to the token and the opportunity to transmit
  • Performs better than a star topology under heavy network load
  • Can create much larger network using Token Ring

Disadvantages

  • One malfunctioning workstation or bad port in the MAU can create problems for the entire network
  • Moves, adds and changes of devices can affect the network
  • Network adapter cards and MAU's are much more expensive than Ethernet cards and switches
  • Much slower than an Ethernet network under normal load

Mesh Topology:

A full mesh topology occurs when every node on the network has a separate wire connecting it to very other node on the network. It provides each device with a point-to- point connection to every other device in the network. A full mesh topology is redundant because if any one node of connection fails, all remaining nodes can continue communicating.

Topology Choice:

I choice star and mesh topology because these two topologies are best topology from other topology. In here establish a network for a police station, this police station has accident & emergency department, maternity department, children's unite, x-ray department and eye department. At first I choice the star topology but it's have some disadvantage the primary disadvantage of a star topology is the high dependence of the system on the functioning of the central switch. While the failure of an individual link only results in the isolation of a single node, the failure of the central switch renders the network inoperable, immediately isolating all departments. The performance and scalability of the network also depend on the capabilities of the switch. Network size is limited by the number of connections that can be made to the switch, and performance for the entire network is capped by its throughput. While in theory traffic between the switch and a node is isolated from other nodes on the network, other nodes may see a performance drop if traffic to another node occupies a significant portion of the central node's processing capability or throughput. Furthermore, wiring up of the system can be very complex. And it has some Advantages too that are:

Better performance:

Passing of Data Packet through unnecessary nodes is prevented by this topology. At most 3 devices and 2 links are involved in any communication between any two devices which are part of this topology. This topology induces a huge overhead on the central switch, however if the central switch has adequate capacity, then very high network utilization by one device in the network does not affect the other devices in the network.

Benefits from centralization:

As the central switch is the bottleneck, increasing capacity of the central switch or adding additional devices to the star, can help scale the network very easily. The central nature also allows the inspection traffic through the network. This can help analyze all the traffic in the network and determine suspicious behavior.

For this reason I also choice star topology. It will be main topology and need a topology it will be help for backup. Then choosing mesh topology that is maximum problem free. If star topology will disturb then mesh topology will help this time. Mesh topology cover dramatically more department and reach more users than other topology by relying on sophisticated mesh switching technology to increase range and topology capacity.

Plug-and-play Setup and Configuration:

Every mesh system works out of the box, without requiring sophisticated site-surveys or command-line setup. Hosted back-end system automatically configures every switch as part of this department topology, and the web-based centralized management shows how everything is working through a simple, intuitive interface that can be used from anywhere in the world.

Scale to Thousands of Simultaneous Users:

Field-tested by one department to other department, Mesh topology platform provides high quality of service to thousands of simultaneous users without missing a beat. Intelligent traffic queuing and packet prioritization, combined with the ability to add an unlimited number of additional network gateways, means your network's capacity can continue to grow with demand.

Interference-aware Mesh Switching:

Instead of relying on a single large antenna to cover every user, each radio in a mesh topology cooperates to find the best path to carry a user's traffic to the Intranet. As they operate, every network re-evaluates thousands of switching paths every minute, resulting in amazing reliability and network capacity. Mesh intelligent mesh switching means every repeater you add extends the reach of the network and makes the mesh more reliable by adding additional links.

That's why I choice star and mash topology. These two topologies are join work together for police station departments. Each department of this police station is very important.

Task: 2

The Internet is an excellent tool for collecting and transmitting data for a police station. It is possible to build a Web site for data entry without much programming experience using commercially available programs. Such a Web site allowed rapid, inexpensive and easy transfer of data between researchers and the coordinating center. It also permitted easy communications between the coordinating center and the investigators. Many technical and practical lessons were learned from this experience so that further systems may be more efficient and reliable.

Once data are entered into the web pages and sent to an end-point (e.g., database, spreadsheet, or e-mail) they are checked and validated remotely by the owner of the end-point. Any feedback is sent to the user with time delay because there is no immediate interaction between the database and the user. This is the easiest way to set up a data entry Web site, but it lacks automatic and immediate interactivity.

One-way data flow with client-sided validation

Validation of the entered data can be performed on the client (browser) side. This is mostly done with JavaScript, a program language developed to run on browsers. The JavaScript code is sent with the HTML code (hypertext markup language, the computer language that defines the way web pages are displayed on a computer) of the web page to the user. It can react to false data entry or missing data with a message box informing the user. The advantage is that basic data check is performed before they are being sent. Yet, client-sided data validation has some major disadvantages (other than the need of programming knowledge). Because the JavaScript code is sent with the HTML code to the browser, the web pages are larger and this may lead to a longer download time, particularly for users with a slow Internet connection. In addition, anyone can see the programming code, a feature not always in the interest of the web site designer.

Enterprise Networking Assignment September 2008 International Advanced Diploma in Computer Studies Enterprise Networking ©NCC Education Ltd 2008

Two-way data flow with server-sided validation

After the data are entered and sent to the server they are validated and checked by a program residing on that server. Depending on the validation result, a new web page is generated by the web server and sent to the user with, for example, a request to reenter incorrect data or to confirm that all data have been correctly entered. With this technique, there is no extra load on the web pages and the programming code is not visible to the user. The main disadvantage (other than the need for extensive programming knowledge) is that the data first have to be sent to the server and a response has to be sent back to the user, the so-called "client-server-client round trip." This may lead to a higher traffic workload, which can be annoying, especially to the user with a slow Internet connection.

Two-way data flow with server and client-sided validation

The combination of the server and client-side interaction seems to be the ideal solution from the point of user friendliness. Simple data validation is performed using client-side scripting, and more complex tasks are performed on the server side. Yet its implementation is time consuming and complex.

Referring case history, status, diagnosis code, textual request are entered by the general practitioner. So instead of entering the detailed referring data, the administrator can choose the current case from the waiting list. On the other hand the family doctor can access his/her patient's care data from the police station information system automatically as the actual police station care had been closed with the final documents. In this way the family doctor can see the treatment's result before patient would show up in the doctor's office with the paper-formed final report. By merging the final report's data of police station cases into the police station application system these data can be accessed for any future patient-visit.

Question: Access issues for patients with disabilities, e.g. blind/partially-sighted.

The police station authority creating a password protected web page on the police station website on which all information pertinent would be posted. A hard copy of the posted information would be available for reference at the police station. Discussion included the possibility of automatic notification to patient when information has been posted and the use of laptop computers at police station for each disable patient to access the posted information during the police station. Patients of the police station expressed their support of this proposal and asked that police station staff to establish a web-based system.

There are two methods of roaming in a node-to-node configuration: Patchwork roaming and Mobile Mesh roaming.

Nodes in a mobile mesh by their very nature roam in and out of coverage and between networks.

With Patchwork roaming, wireless connection between client's hardware and mesh network, a wireless data networks, public Wi-Fi hotspots, and enterprise WLAN's, are difficult to operate at best. The clients using Ipv4 that do not automatically change the IP address when moving between mesh nodes and wireless nodes. Manual intervention may be required. With Patchwork seamless roaming can be achieve; however, it requires DHCP to set every few seconds. The solution will be wait until Ipv6.

Mobile meshes implements self-contained dynamic addressing and rendezvous technologies to simplify address management and enable true nomadic operation without reliance on external clients hardware. Mobile devices can join and leave a mobile mesh and/or connect to public or private fixed infrastructure, all while retaining connectivity to critical services.

Wireless Mesh topology every node has a connection to every other node in the network realm. There is two types of mesh topologies: full mesh and partial mesh.

Full wireless mesh topology occurs when every node in a realm is connected to every other node in a network. Full mesh is yields the greatest amount of redundancy, so in the event that one of those nodes fails, network traffic can be directed to any of the other nodes. Full wireless mesh is difficult to achieve on a large scale using MeshAP; however, small-scale area like offices or small campus may be ideal. One should note that it is difficult to deploy a full mesh topology.

Partial mesh topology yields less redundancy than full mesh topology. With partial mesh, some nodes are organized in a full mesh scheme but others are only connected to one or more nodes in the network realm. Partial mesh topology is commonly found in either small or large networks or fulfilling the last mile connection to a full meshed backbone.

There are 4 main types of partial wireless mesh nodes topologies:

  • Point-to-point
  • Point-to-multipoint or Multipoint-to-point, and
  • Multipoint-to-multipoint,
  • Metropolitan

Point-to-point and point-to-multipoint networks have long been the standard for fixed wireless deployments and some 802.11 based networks. In testing of mesh networks have proven to be most versatile, overcoming a number of disadvantages in traditional wireless topologies. This section will detail the fundamentals of MeshAP and its inherent advantages.

Point-to-Point nodes topology

A point-to-point network is the simplest form of wireless network, composed of two radio and two high gain antennas in direct communication with each other. Point to point links are often used to provide high-performance, dedicated connections or high-speed interconnect links. These links are quick to deploy individually, but do not easily scale to create a large network. Client used these nodes in a site-to-site configuration.

Point to Multipoint nodes topology

A point-to multipoint or a Multipoint to point nodes share link between an uplink node with omni directional antenna and repeater nodes or downlink nodes with high gain directional antennas. This type of network is easier to deploy than Point to point network because adding a new subscriber only requires equipment deployment at the subscriber site, not at the uplink node; however, each remote site must be within range and clear line of sight of the base station. Trees, hills and other line of sight obstruction make point to multipoint nods impractical for residential and home office coverage. A Point to Multipoint network is suited for either backhaul operations or customers that need reliable, high-speed connections, but are not willing to pay for dedicated capacity that may go unused. The nodes performed as a bridge to the uplink network and are generally in wired configuration for the clients. The problem with point to Multipoint node topology is that they are not design to mesh with other nodes due to the directional antenna.

Multipoint nodes topology

Multipoint to multipoint networks creates a routed mesh topology that mirrors the structure of a wired Internet. To build a mesh network, indoor or outdoor Internet access is first established with the deployment of an access switch connected to a wired ISP. Additional access routers are then deployed throughout the coverage area until a maximum density is achieved. Each access router not only provides access for attached users, but also become part of the network infrastructure by routing traffic through the network over multiple hops. This allows any client to join the network at any point of the mesh, even if the clients are not using a node. Client can access the entire mesh wireless or wired making this the best choice to deploy for areas that require larger coverage MeshAP.

Metropolitan nodes topology

Task 3

  • A method of half-duplex wireless communication comprising the steps of: transmitting from a base station to a plurality of mobile stations contained within one wireless communication cell that is serviced by the base station a Ready announcement indicating that the base station is ready to receive data on an uplink channel from the mobile stations, setting a random initial backoff time for each mobile station and transmitting from each mobile station a Request to Send announcement to the base station following expiration of the backoff time, transmitting from the base station to the mobile stations a Clear to Send announcement indicating that the first mobile station to have had its Request to Send announcement received in the base station can now transmit data, resubmitting the Request to Send announcements from the other mobile stations after a predetermined backoff time period has expired corresponding to a time period in which the first mobile station can transmit its data to the base station, and prioritizing any messages from the mobile stations by setting a higher probability that the base station will be in a receiving state rather than a transmitting state.
  • The method according to claim 1 including the steps of transmitting Clear to Send announcements from the mobile stations to the base station indicating that mobile stations are clear to receive data from the base station, and transmitting the data from the base station to a respective mobile station based on the first Clear to Send announcement received within the base station.
  • A half-duplex wireless communication system comprising a premises having a base station that services a defined communication cell, wherein the base station transmits and receives Request to Send and Clear to Send announcements to and from mobile stations to indicate that the base station can receive and send data, and a plurality of mobile stations that send and receive data after transmitting and receiving Clear to Send and Request to Send announcements to and from the base station based on the respective time period in which the base station has received the Clear to Send and Request to Send announcements from respective mobile stations, and means for prioritizing any messages from the mobile stations by setting a higher probability that a base station will be in a receiving state rather than a transmitting state.
  • The system according to claim 3 wherein a Request to Send and Clear to Send announcement exchange must occur between the base station and mobile station before any data exchange can occur.
  • The system according to claim 3 wherein the base station and a mobile station send and receive an acknowledgement message signalling the completion of data transfer.

The main equipment that would be installed.

Requirements Analysis

Prior to any decision on strategy, the customer's requirements for voice services must be clearly defined. Requirement operators will evaluate the current environment and practices, and then recommend strategic infrastructure decisions aligned with the customer's business needs. For an IP Telephony infrastructure, this would include items such as:

  • Call services
  • Phone features
  • Call conferencing services
  • Messaging
  • Toll bypass
  • Directory services.

IP Telephony System Installation Sequence:

Once the infrastructure is ready to support IP Telephony, the actual deployment begins.

The main steps are summarized below:

  • Install IP Telephony Call Manager Publisher server.
  • Configuration of IP Telephony system parameters, calling gateways, dial plan and phone clients.
  • Install IP Telephony Call Manager Subscriber servers as needed.
  • Install IP Telephony Voicemail Solution.
  • Connect the IP Telephony system with minimal access to PSTN and tie line services.

The features available with each system.

Performance and security of the existing network to ensure that it is capable of supporting an IP Telephony infrastructure, and identify any areas where enhancements are necessary. In order to successfully deploy IP Telephony services, a minimum number of system features must be available in a customer's network. For instance:

  • Networks where IP Telephony is to be deployed should be structured on a 3-tier model: Core, Distribution and Access, to ensure an even flow of traffic. A poorly structured design can create unnecessary bottlenecks, impacting performance.
  • User Access nodes must be switch based technology, to provide the bandwidth to the desktop that can best support voice and video.
  • User Access nodes should support multiple virtual LANs (VLANs) within a single switch. This way, voice and data can be configured separately and efficiently, while sharing the same physical infrastructure.
  • The switch must provide 802.1q trucking on user connections, also to allow voice and data traffic to be configured separately.
  • The switch must be able to provide differentiated Quality of Service (QoS) on a user connection. If the switch does not support 802.1q trucking and differentiated QoS on each user connection, the IP Telephony system may still be deployed but a separate connection would be required for the phone and data equipment connections.

Task: 4

The cost of equipment and installation.

Cost of equipment and installation:

The total cost and savings of an IP Telephony infrastructure should be identified and compared to the current costs. Company will examine the infrastructure costs and provide advice on how to invest to maximize the efficiency of the network. Items included in this analysis will include:

  • Hardware
  • Software
  • Network / leased lines
  • Support services.
  • Value recovered from Cisco telephony trade in program

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The cost of operating the system.

Optimized operating cost structure

Staff requirement for delivering voice services

In-house solution VoIP-X solution

Similar savings on server equipment, administration and support staff

Estimated Retail Pricing

The Microsoft Windows Server 2003 R2 licensing model consists of a Server operating system license and incremental Client Access Licenses (CALs) and is designed to allow for complete scalability of your cost in relation to your usage. In addition, Microsoft offers several flexible, cost-effective options for licensing. Note that there are a few CAL types available to suit your individual needs. This page provides guidance on the Windows Server 2003 R2 pricing and points you to our various licensing programs so you can find the most cost-effective solution for your organization.

Product Offering

U.S. Price*

Description

Windows Server 2003 R2 Standard Edition

$999

Available in 32-bit and 64-bit versions. Includes 5 CALs (User or Device, chosen after purchase)

Windows Server 2003 R2 Standard Edition

$1,199

Available in 32-bit and 64-bit versions. Includes 10 CALs (User or Device, chosen after purchase)

Windows Server 2003 R2 Enterprise Edition

$3,999

Available in 32-bit and 64-bit versions. Includes 25 CALs (User or Device, chosen after purchase)

Windows Server 2003 R2 Datacenter Edition

$2,999

Available in 32-bit and 64-bit versions.

Windows Server 2003 Web Edition, 32-bit version

$399 Open NL

Web Server product, no CALs required. Windows Server 2003 Web Edition, is not available in all channels. Open NL estimated price is $399. Contact your local System Builder, OEM, or reseller for actual prices or for more information on how to purchase.

Task: 5

Benefit:

As technical barriers are eliminated and more organizations begin to adopt Internet protocol-based telephony (IPT), companies are finding that here are demonstrable, real-world total costs of ownership (TCO) advantages associated with implementing IPT solutions. Along with delivering the same or better quality and reliability as traditional systems, IPT solutions offer distinct benefits including lower costs, simplified management and greater flexibility to add applications like conferencing, centralized voice mail, and unified messaging, enabling branches to deliver premium service to customers. IPT is able to lower the costs and provide value-added communications applications to employees in branch and retail locations.

Supported network topologies:

“Topology” refers to the configuration of the hardware components and how the data is transmitted through that configuration. 802.15.4 and ZigBee support three different network topologies: star, mesh, and cluster tree (also called star-mesh hybrid). The cluster tree topology is less efficient than the other two, and is therefore rarely (if ever) implemented. It is not covered in this whitepaper. Before describing the star and mesh topologies, it helps to first understand the different types of devices these networks can include.

LAN guard N.S.S. has the ability to scan your entire network, IP by IP, or to scan just a single machine upon which it is installed. Not only do you get a list of open ports and vulnerable services, but you also get useful information such as the service packs installed on the machine, missing security patches, wireless access points, USB devices, open shares, open ports, services/applications active on the computer, key registry entries, weak passwords, users and groups, and more. In addition, you can easily analyze scan results using filters and reports, enabling you to proactively secure your network — for example, by shutting down unnecessary ports, closing shares, installing service packs.

Bibliography:

Search Engines Name:

  • www.google.com
  • www.yahoo.com
  • www.ads.com

******

Web Address Name:

  • http://en.wikipedia.org/wiki/VoIP
  • http://en.wikipedia.org/wiki/Voice_over_Internet_Protocol
  • http://en.wikipedia.org/wiki/IP_Phone
  • http://en.wikipedia.org/wiki/Mobile_VoIP
  • http://en.wikipedia.org/wiki/Comparison_of_VoIP_software
  • http://en.wikipedia.org/wiki/Differentiated_services
  • http://en.wikipedia.org/wiki/ENUM
  • http://en.wikipedia.org/wiki/H323
  • http://en.wikipedia.org/wiki/Integrated_services
  • http://www.manufacturers.com.tw/telecom/WirelessSolution.html
  • http://www.redcom.com/products/slice2100.php
  • http://www.redcom.com/products/hdx_apps.php
  • http://meraki.com/oursolution/mesh/
  • http://www.microsoft.com/technet/network/p2p/p2pintro.mspx EIAAC
  • http://en.wikipedia.org/wiki/Pager
  • http://www.siemon.com/us/white_papers/03-10-10 ip_enhanced_medical.asp
  • http://www.itl.nist.gov/div897/sqg/va/papers/appaper.html
  • http://www.azgita.gov/councils_committees/tegc/submissions/10.pdf
  • http://www.anesthesia-analgesia.org/cgi/content/full/100/2/506

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Books name:

Book Name

Writer Name

Publication Name

Computer Networks(4th edition)

Andrew S. Tanenbaum

Prantic-Hall India

Enterprise Networking

NCC Education Limited


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