Differences between switched Ethernet and shared Ethernet

Http://blog.csdn.net/sailor_8318/article/details/3907345

Differences between switched Ethernet and shared Ethernet

 

A hub, also known as a hub, belongs to the data link layer in the OSI model. However, as the hub is a shared-bandwidth device, the efficiency of the hub becomes very low in the heavy network and is prone to broadcast storms. Therefore, we cannot see hubs in medium and large networks.

 

A vswitch is a network device that can encapsulate and forward data packets based on MAC (hardware address of the network adapter. The switch can "Learn" the MAC address and store it in the internal address table. By creating a temporary exchange path between the initiator of the data frame and the Target receiver, the data frame can directly reach the destination address from the source address.

 

A large number of connected devices, such as hubs or switches, are deployed in the LAN. The LAN connected by a hub is called a shared LAN, and the LAN connected by a switch is called a switched LAN. What are the differences between them?

 

As you know, CSMA/CD (Multi-Channel Access/conflict detection for carrier listeners) is used in Ethernet. For the sender, each time it sends a data message, first, listen to the network. When it detects that the line is empty, it immediately sends data. Otherwise, it continues detection until the line is idle. For the acceptor, first confirm the received signal. If it is sent to itself, it will receive it; otherwise, it will be ignored.

 

When introducing the differences between a hub and a vswitch, let's talk about the two concepts of sharing and switching in the network. For example, if a road with 10 lanes is not marked with a traffic route, a vehicle can only snatch or occupy a road in a disordered state, A vehicle that is prone to traffic jams and reverse driving will crash, reducing the traffic capacity. In order to avoid the above situation, we need to mark the vehicle lines on the road to ensure that each vehicle does its own way and does not interfere with each other. A shared-bandwidth network is equivalent to an unordered state. When the number of data and users exceeds a certain limit, a collision or conflict will occur, leading to a decline in network performance. The exchange network avoids the deficiency of the shared network. The exchange technology is to independently send each information packet from the port to the destination port based on the destination address of the transmitted information packet, it avoids collision with other ports and increases the actual throughput of the network.

 

The main problem with shared Ethernet is that all users share bandwidth. The actual available bandwidth of each user decreases with the increase of the number of users. This is because when the information is busy, multiple users may compete for one channel, while one channel only occupies one user at a certain time, therefore, a large number of monitoring waits often, resulting in jitters, stagnation, or distortion during signal transmission, seriously affecting network performance.

 

In switched Ethernet, the switch provides a dedicated information channel for each user, unless two source ports attempt to send information to the same destination port at the same time, otherwise, the source port and the target port can communicate at the same time without conflict.

A vswitch works in a different way than a hub. Other connection methods and speed options are basically the same as those of a hub.