Introduction to Networking

Unit 8

Lesson 2 - Expanding the Small Network

Traffic Isolation

As we learned in Unit 6, it is often necessary to divide a growing network into physical segments to manage traffic more effectively. As performance becomes an issue, networks can be physically segmented with devices such as switches and routers. By dividing computers and servers into logical workgroups, and isolating the workgroups with such devices, the network becomes more efficient and overall network bandwidth is increased.

We have just discussed how a growing network often creates multiple servers to perform various functions. Some of these servers are specific to various groups or departments, while others are shared by the entire organization. This is shown on the Multiple Servers Diagram. For example, the intranet server and print server are used by all clients; however, the other two servers are each used by a different department.

Multiple Servers

This network configuration provides all nodes equal access to the intranet server and print server. However, when a client communicates with its specialized workgroup server, all nodes receive that traffic as well. If each workgroup server handles many requests, the specialized traffic can degrade performance on the rest of the network.

Adding a Switched Backbone

In a typical migration path (upgrade), the network administrator ties the two hubs together with a switch, and attaches each commonly shared server to its own switch port. This divides the network into two logical workgroups, as shown on the Switched Backbone Diagram.

Switched Backbone

Now, when a client sends data to a server in the same workgroup, that traffic is isolated to that segment of the network. The information will not cross the switch boundary. Also, if a client in one workgroup accesses the intranet server or print server, that traffic will not be transmitted to the other workgroup.

A router may also be used in this configuration, instead of a switch. Like a switch, a router will isolate traffic in individual workgroups when information is being sent between members of the same workgroup. Likewise, information destined for the intranet server or print server will not be visible in the other workgroup. However, a router will not forward broadcast traffic out all ports, as a switch will.

Wireless Bridges

A small network may also begin the process of segmentation when it adds wireless access for its mobile nodes. As we learned in Unit 5, a wireless access point forwards traffic between the hard-wired network and mobile nodes. This arrangement is shown on the Wireless Access Point Diagram.

Wireless Access Point

Some wireless access points function as a Layer 2 bridge, thus the hard-wired network forms one workgroup, while the wireless nodes form another.

Activities

See the Activities and Extended Activities section in Unit 8 Lesson 2 in your textbook Introduction to Networking to test what you have learned so far.

[ Previous Section ] [ Unit Contents ] [ Next Lesson ]