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Ethernet
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- 1ETHERNET Devices on ethernet segment share communication medium, multiple stations can receive but only one can transmit at one timeDominant LAN tech, cheaper than token LAN, ATM
Overview:
IEEE 802.3 <- divided into three parts
1) Speed 2) base or broadband 3) distance, but now rep media - 210 Base2 Ethernet10: 10Mbps
2: under 200 meters max cable length
Thin coaxial cable in bus topology
Repeaters used to connenct multiple segments - 310 BaseT and 100 BaseT10Mbps and 100Mbps (fast etherent)
T = twisted pair
Nodes connect to hib star topology
Max distance 100m between nodes and hub
Hubs are essentially physical layer repeaters - no frame buffering or CSMA/CD, just network management functionality - 4Gigabit EthernetAllows point to point link and shared broadcast channels
>In shared mode = CSMA/CD used; short distances between nodes to be efficient as signal experiences attenuation the longer the distance - 5Logical Link ControlUpper portion of Data Link Layer above MAC
Primary function to provide addressing and control mechanisms
Uses unacked conenctionless services
Data unit = PDU Protocol Data Unit - 6PDU ILength = 46 to 1500 bytes
DSAP and SSAP contain 7 bit addresses [DSAP 0 = goes to individual, 1 = group] /[SSAP 1 = Response, 0 = Command] - 7PDU IIContains control field which identifies frames as I-Frame, U-Frame or S-Frame
i= transport data and related control info
s = transport control such as flow control error correction
u = reserved for system management - 8MAC FrameMAC formats frames from LLC
>Resolves contention
>Has addressing and flow control - 9MAC Format IPreamble = 7 byte repeated 8 bit patter 10101010
Start Delimiter Frame (SFD)
1010101 trailing 11 = start of frame
DA/SA - 6 byte field, 1= broadcast/multicast 2= unicast
LLC DATA (entire LLC PDU, 46-1500 bytes long)
Pad - ensure packet at least 64 bytes
FCS - 32 bit
Frame types
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- Descripción
- Fichas sobre Ethernet, creado por Eric Wojcik el 09/06/2018.
- Creado por
- Eric Wojcik
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