Midterm Review 1

• Introduction– Basic terminology and concepts.

• Physical Layer– Time and frequency domains.– Bandwidth and data rate.– Analog and digital transmission.– Simplex, half-duplex and full-duplex transmission.

Midterm Review 2

• Physical Layer (cont’d)– Transmission impairments.– Decibel.– S/N ratio.– Channel capacity.

• Nyquist.• Shannon.

– Types / properties / advantages / disadvantages of media • Copper (UTP: Cat-3, Cat-5)• Fiber.

Midterm Review 3

• Physical Layer (cont’d)– Data encoding

• Analog-to-digital. – (Time sampling / amplitude quantization)

• Digital-to-analog. – (Data reconstruction)

– Transmission modes.• Synchronous.• Asynchronous.

Midterm Review 4

• Data Link Layer (Error & Flow Control)– Framing– Error detection / correction schemes.

–Parity.–Hamming distance–CRC (polynomial encoding) Flow

control.

Midterm Review 5

– Flow Control – Acknowledgement– Stop and Wait– PAR / ARQ – Sliding Window– Piggybacking– “go back n”– Pipelining– Selective repeat

Bit Length of a Link

• Assume link is fully occupied • 1st bit is just arriving at the receiver• sender has sent continuously

• R = data rate (bps)• d = distance (length of link) (meters)• V = propagation velocity (meters / second)• (~ 2 - 3 x 108 meters/second)• Bit length = Rd / V bits

Midterm Review 6

– DLL / MAC protocols• Static• Dynamic

– Multiplexing.• Frequency-Division Multiplexing (FDM).• Time-Division Multiplexing (TDM).• Statistical Time-Division Multiplexing

(STDM).

Midterm Review 7

• LANs– Protocol architecture.– Ethernet (802.3) design parameters (length, frame

size) standards / reasons– Frame format (not details)– LAN topologies.

Midterm Review 8

• MAC– Centralized and distributed control.– Synchronous and asynchronous.– Asynchronous MAC.

• Round-robin, reservation, and contention.

• LLC for LANs.

Midterm Review 9

• MAC protocols.– Contention.

• ALOHA and Slotted ALOHA.• CSMA.• CSMA/CD.

– Token Passing• Token bus.• Token ring.

Midterm Review 10

• Ethernet– Cabling– Manchester encoding– Backoff– Switched– Performance / speed / length

• High-Speed LANs– FDDI– Fast Ethernet– Gigabit Ethernet

Midterm Review 11

• Wireless LANs– Hidden station problem– MACA / MACAW– RTS / CTS– Frames / Fragments

Midterm Review 12

Encapsulation

Application data

header

header

header

header

TCP

IP

LLC

MAC MACtrailer

TCP segmentIP datagram

LLC PDUMAC frame

Summary

Channel allocation methods and systems for a common channel.

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