What is the difference between an Ethernet switch and an Ethernet hub? Which is more suitable for a network with a high traffic load, a switch or a hub? Explain.

Question

What will be an ideal response?

Answer 1

When a hub receives a packet of data at one of its ports from a PC on the network, it transmits (repeats) the packet to all of its ports and, thus, to all of the other PCs on the network. Switching occurs at the link layer. Switches analyze incoming frames, make forwarding decisions based on information contained in the frames, and forward the frames toward the destination. Ethernet switches are more suitable for a network with high traffic load. Ethernet devices will listen to the wire to make sure it is free before transmitting. Sometimes two or more devices will sense that the wire is free and transmit at the same time. The result is a collision. After a collision, the devices that caused the collision will back off a random amount of time before trying to transmit again. Shared ethernet networks are considered saturated at 40% utilization in most circumstances. All devices plugged into a shared hub or groups of daisy-chained hubs are considered to be in one collision domain. Ethernet switches increase network performance by breaking up connections into multiple collision domains. Most ethernet switches also help with network performance by allow devices to work at their maximum speed 10/100/1000Mbps and/or half or full-duplex. Ethernet switches in their basic form are nothing more than very fast multi-port bridges. Switches have specialized ASIC’s (Application specific Integrated Circuits) that allow bridging decisions based on MAC address to happen at wire speed. Due to the fact that a switch is a bridge, Ethernet frames are only passed to the port(s) that need to see them. A switch keeps a table that lists which MAC addresses are on each port. If the destination MAC address is not in the table it will flood all ports with the Ethernet frame and then populate the table with the required info when the target device with the requested MAC address responds.