- Ethernet is a contention media method that allows all devices on a network to share the bandwidth of a link
- Ethernet utilizes Carrier Sense Multiple Access with Collision Detection (CSMA/CD) to avoid packets collisions
- When collision occurs, a jam signal is send to all device to stop transmission until the backoff timer expire
- Half-duplex Ethernet use one wire pair and share a collision domain
- Full-duplex Ethernet use two wire pairs and has own collision domain (no hub)
- Ethernet at Layer 2 is responsible for Hardware/MAC addressing
- Ethernet MAC address format:
I/G = Individual/Group (broadcast or multicast) bit = 0/1
G/L = Global/Local bit = 0/1
OUI = Assigned by IEEE to org
- Ethernet frame format:
Preamble = provides a 5 MHz clock at start of packet to lock incoming bit stream
DA = Destination Address
SA = Source Address
Type = Network Layer protocol identification
Data = Packet from Layer 3 to 2 (64-1500 bytes)
FCS = Frame Check Sequence (for CRC storing)
- IEEE 802.3 Standard:
10Base5 = 10Mbps, baseband, up to 5oom (thicknet)
10BaseT = 10Mbps, category 3 UTP wiring
100BaseTX = 100Mbps, category 5, 6, 7 UTP two-pair wiring, 100m (802.3u)
100BaseFX = 100Mbps, 62.5/125 micron multimode fiber, 412m (802.3u)
1000BaseCX = 1Gbps, copper twisted-pair(twinax), 25 m (802.3z)
1000BaseT = 1Gbps, category 5 UTP four-pair wiring, 100m (802.3ab)
1000BaseSX = 1Gbps, 62.5/50 micron multimode fiber, 220m/550m (802.3z)
1000BaseLX = 1Gbps, 9 micron single mode fiber, 3-9km (802.3z)
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