Questions and Answers
What does MTBF stand for in network reliability?
Mean Time Between Failures
Calculate the network availability probability when links are arranged in series.
(1-b1)(1-b2)(1-b3)...
What is the formula for normalized propagation delay?
a = Time of Propagation / Time of Frame transmission
What is the formula for Link Utilization (U)?
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What is the formula relating window size (N) to sequence bits (K)?
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What is the first step in the Go Back N protocol with sliding window?
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What is Distance Vector Routing?
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What are the stages of Link State Routing?
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What does BGP stand for and its primary usage?
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Describe UDP.
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What is the TCP connection management three-way handshake process?
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How does TCP flow control work?
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What is the purpose of delayed ACK in TCP?
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Explain TCP error control and its scenarios.
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What is the congestion control algorithm in TCP?
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What is the formula for maximum TCP throughput?
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Study Notes
Network Reliability Parameter
- Mean Time Between Failures (MTBF) consists of Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR), expressed as MTBF = MTTF + MTTR.
Network Availability Probability Calculation
- For series connections, calculate availability as the product of the probabilities that each link will work: (1-b1)(1-b2)(1-b3)*...
- For parallel connections, compute the probability that all links will fail: b1b2b3*...*bn.
- In mixed configurations, decompose into paths and convert parallel paths to single paths for series.
Normalized Propagation Delay
- Expressed as a = Time of Propagation / Time of Frame Transmission.
Throughput (U) Link Utilization
- Utilization (U) is calculated with the formula U = 1 / (1 + 2a).
Sliding Window Protocol
- The window size, N, is linked to sequence bits K with the formula N = 2a + 1.
- Utilization (U) relates to N as follows: U = 1 when N = 2a + 1; U = N(1-P)/(2a + 1) when N < 2a + 1.
Go Back N Protocol
- Employs a sliding window of size N.
Distance Vector Routing
- Neighbors are discovered via multicast requests.
- Distance vectors are exchanged in response to requests or periodically.
- Shortest paths are computed using the Bellman-Ford algorithm.
- Addresses the count-to-infinity problem using techniques like Split Horizons and Poison Reverse.
Link State Routing
- Involves discovering neighbors through multicast hello messages.
- Constructs a Link State Advertisement (LSA) and floods it to all routers.
- Builds a link state database to calculate the shortest path using Dijkstra's algorithm.
Border Gateway Protocol (BGP)
- Operates between gateway hosts on the Internet to manage routing tables and select optimal routes.
- Utilizes TCP for communication between routers.
Transport Protocols
- UDP is connectionless, unreliable, and suitable for real-time applications like online gaming.
- TCP is connection-oriented, reliable, and stream-focused, commonly used for file transfer (FTP) or video streaming.
UDP Datagram Structure
- Header includes source port, destination port, message length, and checksum, totaling a min size of 8 bytes and a max size of 65535 bytes.
TCP Connection Management
- Initiated via a three-way handshake involving SYN, SYN-ACK, and ACK segments.
- Closing involves a four-step process using FIN segments.
TCP Flow Control
- Utilizes a receive window size that adjusts data transmission to optimize bandwidth usage according to the receiver's capacity.
Flow Control Enhancements
- Delayed ACK reduces acknowledgment packets by waiting before sending.
- Controls silly window syndrome using Clark's solution and the Eagle algorithm to manage small segment transmissions.
TCP Error Control
- Different scenarios trigger retransmissions to address out-of-order, duplicated, corrupted, and lost segments.
TCP Timeout Retransmission
- Calculates retransmission time using algorithms like Jacobson's and Karn's, adjusting for initial and subsequent Round Trip Times (RTT).
TCP Error Control Enhancement
- Implements fast retransmit upon receiving three duplicate ACKs instead of waiting for a timeout.
TCP Congestion Control
- Manages the congestion window size with phases of slow start and avoidance; triggers fast recovery upon detecting packet loss.
TCP Throughput
- Maximum throughput is achieved when the congestion window (CWND) is at its maximum, calculated as (cwnd * MSS) / RTT.
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Description
This quiz features essential formulas related to computer networks, focusing on network reliability parameters and availability probabilities. Test your understanding of mean time between failures and calculations for network availability based on different configurations. Ideal for students and professionals looking to reinforce their knowledge in networking.