Networking
Remember it
Never forget how a switch handles frames
Never forget how a switch handles a frame again
Quick check · tap an answer to continue
Lesson notes
Explain why networks use layers and map OSI's 7 layers to the TCP/IP model's 4 layers
Key points
- Lazy / Learn source MAC: Lazy means learn: the switch records the source MAC and its arrival port.
- Students / Search MAC table: Students means search: it looks up the destination MAC in its table.
- Find / Forward to one port: Find means forward: a known destination goes out only its matching port.
- Free / Flood unknown: Free means flood: an unknown destination goes out every port except the incoming one.
- Food / Filter same port: Food means filter: a frame whose destination sits on the incoming port is dropped.
Takeaway: Learn, search, forward, flood, filter: switches work on MAC addresses.
Quick check: What does a switch do with a frame whose destination MAC is not in its table?
- Drops the frame
- Floods all other ports
- Sends it to the router
Unknown destinations are flooded out every port except the one the frame arrived on.
OSI modelTCP/IP modelencapsulationprotocol
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