Physical Vs. Logical Network Design

Physical vs. Logical Network Design

Bob Jones

NTC 410

Fernando Casafranca

April 11, 2006

How is your network designed? This is a simple question. But, like many things in the information technology field, not a question with a simple answer. The definition of network design to a customer or user can be completely different than to an information technology professional. Even inside of the information technology field, there are several definitions of network design. We use the words Logical Network Design and Physical Network Design to help clear up some of this confusion. In the course of this paper we will define Logical and Physical Network Design, explain some of the differences, and provide examples of each to help illustrate the point.

Logical Network Design (sometimes called Virtual Network Design) defines the logical parts of a network. In this case logical means the relationship between elements and between an element and the whole in a set of objects, individuals, principles, or events. (Dictionary,2006) Logical design concentrates on the links between network systems, how they relate to each other and the users. Some things that would be included in a Logical Network Design are:

* IP Addresses: In computer networking, an IP address (internet protocol address) is a unique number that devices use in order to identify and communicate with each other on a network utilizing the Internet Protocol standard (IP). Any participating network device including routers, computers, time-servers, printers, internet fax machines, and some telephones -- must have its own unique address. (Wikipedia, 2006)

* Subnets: In the Internet Protocol (IP), a subnetwork (or subnet) is a division of a classful network. Subnetting an IP network allows you to break down what appears (logically) to be a single large network into smaller ones. (Wikipedia, 2006)

* Domains: A Windows Server domain, a centrally-managed group of computers using the Windows operating-system. (Wikipedia, 2006)

"A logical network layout clearly shows the IP Addresses associated with each part of the network. In most cases, the logical network is a simple Class C network such as 192.168.0.0 with the default subnet mask of 255.255.255.0. This network allows up to 254 hosts to be connected directly to it without the need of any routing."

(Partsenidis. 2006)

One thing that Logical Network Design does not do is concern itself with connection types or equipment; this is the realm of the Physical Network Design

Physical Network Design is heavily dependent

on the layout of the building and or enterprise system that will house the network. When creating a Physical Network Design, the designer must consider physical issues such as distance between equipment and building layout. Some things that may be represented on a Physical Network Design are:

* Equipment: Specific equipment will be show, such as switches, hubs, and routers.

* Systems: Systems that will be placed in the network will be show, these include PCs, servers, workstations and even fax machines, printers and storage devices.

* Cabling: The type quantity and length of connections and the media used to make these connections. Typical cabling connections include cat