Exit Zen
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../../principles/reliability.rst:167
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Manchester encoding
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../../principles/sharing.rst:167
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If the buffer's occupancy continues to grow, it will overflow and packets will need to be discarded. Discarding packets during congestion is the second possible reaction of a network node to congestion. Before looking at how a node can discard packets, it is interesting to discuss qualitatively the impact of the buffer occupancy on the reliable delivery of data through a network. This is illustrated by the figure below, adapted from [Jain1990]_.
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../../principles/transport.rst:82
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A simple BNF specification
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../../bibliography.rst:121
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McKeown N, Anderson T, Balakrishnan H, Parulkar G, Peterson L, Rexford J, Shenker S, Turner J., `OpenFlow: enabling innovation in campus networks <https://doi.org/10.1145/1355734.1355746>`_. ACM SIGCOMM Computer Communication Review. 2008 Mar 31;38(2):69-74.
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../../glossary.rst:161
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The Enhanced Interior Gateway Routing Protocol (EIGRP) is a proprietary intradomain routing protocol that is often used in enterprise networks. EIGRP uses the DUAL algorithm described in [Garcia1993]_.
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../../exercises/ex-sharing.rst:645
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Like ALOHA, CSMA relies on acknowledgments to detect where a frame has been correctly received. When a host senses an idle channel, if should transmit its frame immediately. How should it react if it detects that another host is already transmitting ? Consider two options :
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../../exercises/network.rst:360
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Routes on A
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../../exercises/reliability.rst:83
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Is it possible for a go-back-n receiver to inter-operate with a selective-repeat sender ? Justify your answer.
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../../exercises/sockets.rst:322
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Note that we can reuse our ``send_hello_to_peer`` function without any modification as we wrote it to handle any kind of sockets, including sockets using the IPv6 network protocol.
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../../principles/network.rst:140
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Some networks use the arrival of packets as the trigger to compute the corresponding entries in the forwarding tables. Several technologies have been built upon this principle. When a packet arrives, the router consults its forwarding table to find a path towards the destination. If the destination is present in the forwarding table, the packet is forwarded. Otherwise, the router needs to find a way to forward the packet and update its forwarding table.
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../../principles/referencemodels.rst:141
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Besides this difference in the lower layers, the TCP/IP reference model is very close to the five layers that we use throughout this document.
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../../principles/sharing.rst:175
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When the network load is low, buffer occupancy and link utilization are low. The buffers on the network nodes are mainly used to absorb very short bursts of packets, but on average the traffic demand is lower than the network capacity. If the demand increases, the average buffer occupancy will increase as well. Measurements have shown that the total throughput increases as well. If the buffer occupancy is zero or very low, transmission opportunities on network links can be missed. This is not the case when the buffer occupancy is small but non zero. However, if the buffer occupancy continues to increase, the buffer becomes overloaded and the throughput does not increase anymore. When the buffer occupancy is close to the maximum, the throughput may decrease. This drop in throughput can be caused by excessive retransmissions of reliable protocols that incorrectly assume that previously sent packets have been lost while they are still waiting in the buffer. The network delay on the other hand increases with the buffer occupancy. In practice, a good operating point for a network buffer is a low occupancy to achieve high link utilization and also low delay for interactive applications.
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../../principles/transport.rst:84
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The example above defines several terminals and two commands : `usercommand` and `passwordcommand`. The `ALPHA` terminal contains all letters in upper and lower case. In the `ALPHA` rule, `%x41` corresponds to ASCII character code 41 in hexadecimal, i.e. capital `A`. The `CR` and `LF` terminals correspond to the carriage return and linefeed control characters. The `CRLF` rule concatenates these two terminals to match the standard end of line termination. The `DIGIT` terminal contains all digits. The `SP` terminal corresponds to the white space characters. The `usercommand` is composed of two strings separated by white space. In the ABNF rules that define the messages used by Internet applications, the commands are case-insensitive. The rule `"user"` corresponds to all possible cases of the letters that compose the word between brackets, e.g. `user`, `uSeR`, `USER`, `usER`, ... A `username` contains at least one letter and up to 8 letters. User names are case-sensitive as they are not defined as a string between brackets. The `password` rule indicates that a password starts with a letter and can contain any number of letters or digits. The white space and the control characters cannot appear in a `password` defined by the above rule.
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../../bibliography.rst:126
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McQuillan, J. M., Richer, I., and Rosen, E. C., `An overview of the new routing algorithm for the ARPANET <http://doi.acm.org/10.1145/800092.802981>`_. In Proceedings of the Sixth Symposium on Data Communications (Pacific Grove, California, United States, November 27 - 29, 1979). SIGCOMM '79. ACM, New York, NY, 63-68.
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../../glossary.rst:325
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Ethernet
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../../exercises/ex-sharing.rst:647
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the host continues to listen until the communication channel becomes free. It transmits as soon as the communication channel becomes free.
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../../exercises/network.rst:360
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Routes on B
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../../exercises/reliability.rst:85
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Is it possible for a selective-repeat receiver to inter-operate with a go-back-n sender ? Justify your answer.
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../../exercises/sockets.rst:326
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Endianness: exchanging integers between different computers
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../../principles/network.rst:143
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Computing forwarding tables
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