Logical & Physical Design of Network

Logical and Physical Design of a Network

NTC410

Why is it useful to use both a physical and a logical network design? A physical layout of the network shows the physical location of and the connections between devices participating on the network. In such diagrams, workstations are usually represented with small computer icons, servers with full tower cases, and switches. The Logical Design is the IP structure of your network depending on the services that will be provided to clients, you might need to analyze the possible traffic patterns that might result from your plan. Locate potential bottlenecks and, where possible, alleviate them by providing multiple paths to resources or by putting up servers that provide replicas of important data so that load balancing can be provided. The following are other factors to consider:
• Who are the clients? What are their actual needs? How have you determined these needs from user complaints or from help-desk statistics? Is this data reliable?
• What kinds of services will you provide on the network? Are they limited in scope? Will any involve configuring a firewall between LANs? And if so, that still doesn't account for configuring a firewall to enable access to the Internet.
• Will you need to allow an Internet connection for just your internal network's users, or will use you need to allow outside vendors access to your network? One example that comes to mind is the Internet Printing Protocol .
• What will it cost to evaluate what kind of services user groups need to access from the Internet?
• Will you need to allow all users to use email within the internal network and through the firewall on the Internet? The same goes for what sites users will be allowed to access using a network browser and other network applications.
• Will you have users who work from home and require dial-in or VPN access through the Internet? How important it is to let all users have unlimited access to the Internet. If users need to exchange email with vendors, outside consultants, or customers, for example, then you should be sure to send this traffic through a content filter or firewall, and use virus-protection software to detect and prevent malicious code or virus-infected attachment Applications such as FTP allow users to send or receive files from remote systems. Can you trust each employee to use this application without abusing it? From a security point of view, it is usually considered very improper to allow any new application to be loaded on any computer desktop or server without first submitting the application to testing to ensure that is necessary and is not a security risk. Don't leave any backdoors into or out of your network. Below is an example of a WAN logical network diagram. The Physical design will be the topology being used after you've decided on the network protocols and the services you need to offer on the network, identified potential bottlenecks, and evaluated the security problems associated with your network needs, you can then design the physical aspects of the network. There are tools you can use, such as Visio, to draw a physical network diagram. Tools can be expensive but make a better presentation to management than hand drawn network layouts. Whichever tool you decide to use to create the actual network drawings, be sure that the drawings are clear and concise. Looking back at your network application requirements, bandwidth requirements, you can then start designing the physical network, deciding where to place important servers and devices. Below is an example of a physical network diagram. After you have determined your network requirements, you must identify and then select the specific capability that fits your computing environment.

References

http://www.more.net/technical/netserv/diagrams/wanlogical.html
http://www.more.net/technical/netserv/diagrams/documenting/index.html