MAC address aka BIA = OUI + EID
OUI = Oraganizational Unique Identifier from IANA
EID = Equipment Identifier

router crossover router
switch crossover switch straight router
pc(layer3) crossover router(layer3)

Types:

1. UNICAST: one NIC
2. MULTICAST: OUI reserved ( mac address 01-00-5E-xx-xx-xx)
3. BROADCAST: MAC broadcast

DataLink Sublayers
LLC responsible for adding control information to IP packet to help deliver the packet to the right destination
MAC responsible for Data encapsulation and Media access control (adds a header and trailer to form an OSI Layer 2 PDU)

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Ethernet protocol

-underline logical topology: multi-access bus
-networking method: Connection Based (any device can try to transmit data on media)
-CSMA/CD collision detection proccess -Min size 64 bytes Max size 1518 bytes , anything smaller is considered "collision fragment" and is automatically discard