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Open Systems Interconnect Model (OSI) Introduction
Router shown as a circle - Thunderbolt is a serial connection
Layer One - Physical
Cables
Repeaters
Hubs repeats the signal to all other ports except the port that originated the signal
Base - Baseband - one at a time Broadband - More than one signal at a time
Layer Two - Data Link
- controls data on the immediate physical link between devices
MAC Media Access Control 48 bits hexidecimal
OUI Field 24 bits is vendor specific
7th most significant bit - UL - if turned off (0) - the address should be universally unique – The 7th bit turned on (1) - the address has been assigned locally
Protocal unit called a frame FCS - Frame Check Sequence aka CRC - cyclic redundancy check
Switches work here
Switches learn MAC addresses by looking at the source address field in the frame Switches make their forwarding decisions based on the destination MAC address in the frame Once the MAC tabe
Flood is not the same as a broadcast, flood is done when broadcast has all FF in the destination MAC address in the frame broadcast is a one to all transmission sent on purpose unicast is a one to one sent message
Cisco packet tracer CLI → show mac address-table
DYNAMIC → switch learned port
bia - burned in address
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