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21 Cards in this Set
- Front
- Back
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What are two main approaches for scheduling medium access control? |
Reservation and polling |
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What are two Reservation Systems? |
Centralized: central controller accepts requests from stations and issues grants to transmit Distributed: Stations implement a decentralized algorithm to determine transmission order |
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What is reservation interval? |
Reservation interval has minislots that station use to request reservations for data frame transmission |
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What is the efficiency of Reservation Systems in TDMA single frame reservation? |
Assume minislot duration = vX |
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What is the efficiency of Reservation Systems in TDMA k frame reservation? |
, if there are M stations |
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What protocol do the stations use on reservation minislots? |
Stations use slotted ALOHA |
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What are the 2 types of polling systems? |
Centralizing polling: central controller transmits polling messages to station in a certain order Distributed polling: permit for frame transmission is passed from station to station in a certain order |
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What is Walk time? |
Measured from when a station completes transmission to when the next station begins transmission, ie. overhead |
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What is Cycle time? |
Measured as the time between consecutive polls of a given station |
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What is overhead per cycle? |
overhead per cycle = total walk time/cycle time |
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What is Average Cycle time? |
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What is the efficiency of polling systems? |
For exhaustive service: p (stations empty buffers when polled) => where p = lambda * X For limited service: 1/(1 + t/X)) (single frame per poll) |
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What are the assumptions for Token Ring Throughput? |
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What is the token ring throughput for single frame operation? |
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What is the token ring throughput for single token operation? |
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What is the token ring throughput for multi token operation? |
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Depending on a, which token reinsertion strategy is acceptable? |
a << 1: any token strategy a ~ 1: single token strategy a > 1: multiple token strategy |
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Overview of ALOHA and Slotted ALOHA |
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Overview of CSMA/CD |
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Overview of Reservation |
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Overview of Polling |
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