CertiGuide to Network+  9  Chapter 0000:  Network Basics       9  V  Network Models for Resource Sharing

Sneaker Net 1 Client/Server Model

The peer-to-peer model is one in which resources are shared by computers which are considered approximately “equals” in the network administration hierarchy.

Think of your peers at work. You probably share things back and forth, and among your colleagues, who report to the same supervisor, all probably have about equal authority in the organization. No one has control over resources other than those that reside on their own computer.

For example, Joe has control of Joe’s resources, and Meredith has control of Meredith’s resources. Some modern-day real world examples of peer-to-peer networks would be Internet music-sharing services such as Napster and Gnutella.

In peer-to-peer networks, each user has the ability to control security functions for the resources on his or her computer, because his or her computer handles its own security, rather than using a centralized service to do so. The peer-to-peer model stores this security information on the local PC that is granting access. Additionally, each computer may maintain its own list of users that have access to it, and the passwords for those users, to allow security controls on a user-by-user basis. The user responsible for the computer is in charge of updating the lists of permissions and users, as network needs change.

One of the down sides to peer-to-peer networking is that each time a new user is added to the network, potentially every computer would need to be updated separately, to give that user access to each computer’s resources. As you might imagine, not all peer-to-peer networks require every user to be in a list on every computer. If they did, no one using Napster would ever get any music, because they’d spend all their time maintaining user lists.

The peer-to-peer model means that resources are scattered throughout the network, on machines controlled by individual users. One thing that can happen when resources are shared peer-to-peer is that you might need a resource on Susan’s computer, but Susan is out of the office for the day and left her computer powered down. In order to access the resource before Susan returns, you’d need to find someone near her desk and ask them to power up her machine so that its resources are available for your use. In that way, peer-to-peer computing can be less reliable and less fault tolerant, than client/server computing, where a centralized organization makes sure that all resources under their control are available when required, without needing a particular user’s cooperation.

Sneaker Net 1 Client/Server Model