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
Layer 2 - Broadcast Domains
switch = transparent bridging
Broadcast - all switches are one broadcast domain by default Broadcast - can not transverse a router
Collision domains -
Encapsulation = layer header + data
4- Transport Layer chunk of data = Segment -
3- Network Layer - chunk of data - packet
2- Data Link Layer - chunk of data - frame - Ethernet - MAC address
1- Physical Layer
Data Networks and Addressing
Addressing at the Data Link Layer - frame
media access control - 48 bit hexadecimal number local address MAC -
1st 24 bits = manufacturer ID
2ne 24 bits = serial number
Packet Internet or Inter-Network Groper (PING) used to test the reachability of a host on an Internet Protocol (IP) network.
Cisco Certifications
- Entry Level - CCENT - Entry Network Technician
- Associate - CCNA - Network Associate - most common - Route/Switch
- Professional - CCNP - Network Professional
- Expert - CCIE - Internetworking Expert
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