The Layer-2 switches functioning in detail.


Layer-2 switching is hardware-based, It means it uses the MAC address from the host’s NIC cards to filter the network. A layer-2 switch generally uses as a multiport bridge. Layer-2 switches are quick as a result of they are doing not verify the Network layer header information, looking instead of at the frame’s hardware addresses before deciding to either forward the frame or drop it. 

Layer-2 switching provides the following:

  •  Hardware-based bridging (MAC) 
  •  Wire-speed 
  •  Low latency
  •  Low-cost 


The layer-2 switch increases bandwidth for every user as a result of each connection into the switch is its own collision domain, so we are able to connect multiple devices to every interface.


Limitations of Layer-2 Switching: 

Remember that bridges are good if we design our network correctly. The bridged networks break up collision domains, but the network is still one large broadcast domain. Layer-2 switches cannot break up broadcast domains, which can cause performance issues and limit the size of our network.

Bridging VS LAN Switching:

  • Layer-2 switches are extremely simply bridges with a lot of ports. However, there are some important differences we should be aware of: 
  • Bridges are software-based, while switches are hardware-based because they use an ASICs chip to help make filtering decisions. 
  • Bridges will solely have one spanning-tree instance per bridge, whereas switches will have several. Bridges will solely have up to sixteen ports, whereas a switch can have hundreds.  
Forward/filter decisions:

When a frame is received on an associated interface, the switch looks at the destination hardware address and finds the exit interface in the MAC database. The Spanning-Tree Protocol is used to stop network loops and allow redundancy, Address learning, and forward and filtering decisions. 


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