3Com 3C16790-US User Guide - Page 9

How the Switch Can Be Used Switching When a network of repeater hubs is in operation, any information that is sent by the workstations is passed around the whole network (regardless of the destination of the information). This can result in a lot of unnecessary traffic that can slow the network down. The Switch solves this problem because it 'listens' to the network and automatically learns what workstations can be reached through its ports. It can then selectively pass on any information by transmitting the traffic from the relevant port only (instead of all ports like a repeater hub). This operation is called 'switching'. The Switch effectively divides up your network, localizing the network traffic and passing on traffic as necessary (as shown in Figure 2). If you have workstations that communicate frequently in the same part of the network, traffic between them is not passed on unnecessarily to the remainder of the network, thereby reducing the load. If you have any high performance workstations that require a lot of bandwidth, connect them directly to the Switch. The Switches have an additional new feature to aid network performance at times of excessive load. It is called Priority Queuing. When a packet is received, the Switch will examine it to see if it has been priority encoded. If it has the Switch will then read the priority level and determine whether it should be directed through the normal or high priority channel. This feature can be useful for example during excessive loads when one type of traffic may require priority over another. The Switch is configured to to comply with VLAN priority tagged frames and IP TOS / DSCP priority encoded frames. Figure 2 The Switch Separates Your Network and Controls the Information Effectively 10BASE-T OfficeConnect hub OfficeConnect Switch 100BASE-TX OfficeConnect hub 100BASE-TX High performance workstation 8