Cisco Switching Modes Tutorial Cisco CCNA Certification

Cisco Switching Modes Tutorial Cisco CCNA Certification
To pass the CCNA exam & earn that coveted certification, you've got to know Cisco switches inside & out. Among the lots of important details you've got to know are the three methods that Cisco switches use to forward frames, & the differences between the three.

The first switching method is Store-and-Forward. The name is the recipe, because that is what the switch does - it stores the entire frame before beginning to forward it. This method allows for the greatest amount of error checking, since the Frame Check Sequence (FCS) can be run before the frame is forwarded. As always, there's a tradeoff, since this error checking process makes this the slowest of the three frame forwarding methods.

The middle ground between these three extremes is Fragment-Free, so named since fragmented frames won't be forwarded. The switch examines only the first 64 bytes of the frame for errors, since that is the part of the frame that will be damaged in case of a collision. there's error checking, but it's not as thorough as Store-and-Forward.

The quickest method is Cut-Through, where only the destination MAC address of the frame is examined before the forwarding process begins. This means that the part of the frame is actually being forwarded as it's still being received! The tradeoff here is that the FCS does not run, so there's absolutely no error checking with Cut-Through switching.

Keeping these three switching schemes straight is vital to your CCNA exam efforts, & it will help you in working with Cisco switches in the real world as well. Keep studying!