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Chapter5Summary.pdf Flashcards
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Chapter5Summary.pdf Flashcards
Chapter5Summary.pdf Flashcards
Study
Untitled Flashcards
Study
Untitled Flashcards
Study
Untitled Flashcards
Study
Question
What are the two quantitative metrics by which network performance is evaluated?
Answer
Latency and throughput.
Question
How are latency and throughput influenced?
Answer
They are influenced by hardware as well as software overheads.
Question
Why does the TCP header have a HdrLen field?
Answer
The TCP header has a HdrLen field because the header can be of variable length, and the variable part of the TCP header contains the options that have been added.
Question
What happens to throughput as the messages get larger?
Answer
Throughput improves as the messages get larger because the overhead is spread out over more bytes. The throughput curve flattens off above 1 KB, at which point the per-message overhead becomes insignificant compared to the large number of bytes that the protocol stack has to process.
Question
What was one of the concerns when implementing gigabit networks?
Answer
One of the concerns was if TCP would be up for the challenge, which it has been. The introduction of window scaling was one of the most important factors to deal with larger bandwidth-delay products.
Question
What are the differences between stream-oriented and request-reply protocols?
Answer
Stream-oriented protocols like TCP are reliable and unreliable, while request-reply protocols are more suitable for interactive video applications where a dropped frame is not as bad as the delay of retransmission.
Question
Why might TCP not be suitable for request-reply applications?
Answer
TCP is a byte-oriented protocol rather than a message-oriented protocol, and request-reply applications always deal with messages. TCP delivers bytes in order to the application, which may hold onto bytes that were received out of order, causing potential delays.
Question
What led to the creation of the Stream Control Transmission Protocol (SCTP)?
Answer
The need for a protocol that provided a partially ordered delivery service rather than the strictly ordered service of TCP, as well as support for multiple IP addresses for a single session, led to the creation of SCTP.
Question
What are the explicit setup-teardown phases in TCP implementation?
Answer
TCP chose to implement explicit setup-teardown phases to give the receiver the opportunity to reject the connection before any data arrives. In the case of teardown, TCP takes a conservative approach to avoid complications with applications like Telnet that want to keep a connection alive for extended periods.
Question
What is the difference between a window-based protocol and a rate-based design?
Answer
TCP is a window-based protocol, while a rate-based design involves the receiver informing the sender of the rate at which it is willing to accept incoming data. The sender adjusts the rate by increasing or decreasing the advertised window size, which is fed back to the sender in the AdvertisedWindow field of the ACK for every segment.
