Knowing your networks frame sizes enables you to ensure that your users' message traffic gets to where it needs to go quickly and accurately.
Suppose your corporate mailroom is equipped only to handle letter- and business-sized envelopes and is not equipped to handle postcards or larger legal-sized envelopes. The letter-sized envelope is the minimum size, and the business-sized envelope is the maximum sized "frame" allowed by your mailroom. Anything smaller than the letter-sized envelope, such as a postcard, might be considered a runt, and anything larger than the business-sized envelope might be considered a giant.
The image demonstrates the concept of a minimum and maximum frame size, and the result, in a corporate mailroom.
In this mailroom (switch) scenario, both the postcards (runts) and legal-sized envelopes (giants) would not be accepted by the mailroom (the switch) and therefore would be dropped into the trash.
The maximum frame size is also known as the maximum transmission unit, or MTU. When a frame is larger than the MTU, it is broken down, or fragmented, into smaller pieces by the Layer 3 protocol to accommodate the MTU of the network.
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