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../../principles/referencemodels.rst:117
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datalink layer entities exchange *frames*
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../../principles/reliability.rst:70
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This transmission scheme has been used in some early networks. We use it as a basis to understand how hosts communicate. From a Computer Science viewpoint, dealing with voltages is unusual. Computer scientists frequently rely on models that enable them to reason about the issues that they face without having to consider all implementation details. The physical transmission scheme described above can be represented by using a `time-sequence diagram`.
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../../principles/sharing.rst:141
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Congestion collapse is unfortunately not only an academic experience. Van Jacobson reports in [Jacobson1988]_ one of these events that affected him while he was working at the Lawrence Berkeley Laboratory (LBL). LBL was two network nodes away from the University of California in Berkeley. At that time, the link between the two sites had a bandwidth of 32 Kbps, but some hosts were already attached to 10 Mbps LANs. "In October 1986, the data throughput from LBL to UC Berkeley ... dropped from 32 Kbps to 40 bps. We were fascinated by this sudden factor-of-thousand drop in bandwidth and embarked on an investigation of why things had gotten so bad." This work lead to the development of various congestion control techniques that have allowed the Internet to continue to grow without experiencing widespread congestion collapse events.
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../../principles/transport.rst:62
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`A` : `1000011b`
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../../bibliography.rst:94
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Jacobson, V., `Congestion avoidance and control <http://doi.acm.org/10.1145/52324.52356>`_. In Symposium Proceedings on Communications Architectures and Protocols (Stanford, California, United States, August 16 - 18, 1988). V. Cerf, Ed. SIGCOMM '88. ACM, New York, NY, 314-329.
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../../glossary.rst:283
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dial-up line
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../../exercises/ex-sharing.rst:582
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Compute the max-min fair bandwidth allocation in the network below.
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../../exercises/network.rst:250
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The network below uses port forwarding tables. It has been running for several hours and all hosts have exchanged packets. What is the content of the port forwarding tables ?
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../../exercises/sockets.rst:264
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A program can use the ``socket`` system call to create a new socket.
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../../principles/network.rst:108
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In a network, a path can be defined as the list of all intermediate routers for a given source destination pair. For a given source/destination pair, the path can be derived by first consulting the forwarding table of the router attached to the source to determine the next router on the path towards the chosen destination. Then, the forwarding table of this router is queried for the same destination... The queries continue until the destination is reached. In a network that has valid forwarding tables, all the paths between all source/destination pairs contain a finite number of intermediate routers. However, if forwarding tables have not been correctly computed, two types of invalid paths can occur.
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../../principles/referencemodels.rst:118
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network layer entities exchange *packets*
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../../principles/transport.rst:63
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`0` : `0110000b`
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../../bibliography.rst:95
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Jain, R., `Congestion control in computer networks : Issues and trends <https://dx.doi.org/10.1109/65.56532>`_, IEEE Network Magazine, May 1990, pp. 24-30
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../../glossary.rst:285
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A synonym for a regular telephone line, i.e. a line that can be used to dial any telephone number.
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../../exercises/ex-sharing.rst:588
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Simple network topology
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../../exercises/network.rst:273
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At this point, a new link is added between `R1` and `R3`. What happens for the forwarding of packets ?
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../../exercises/reliability.rst:62
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The Cyclic Redundancy Checks (CRCs) are efficient error detection codes that are able to detect :
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../../exercises/sockets.rst:270
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The ``domain`` parameter specifies the address family that we will use to concretely perform the communication. For an IPv6 socket, the ``domain`` parameter will be set to the value ``AF_INET6``, telling the operating system that we plan to communicate using IPv6 addresses. The ``type`` parameter specifies the communication guarantees that we need. For now, we will use the type ``SOCK_DGRAM`` which allows us to send *unreliable messages*. This means that each data that we send at each call of ``sendto`` will either be completely received or not received at all. The last parameter will be set to ``0``. The following line creates a socket, telling the operating system that we want to communicate using IPv6 addresses and that we want to send unreliable messages.
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../../principles/network.rst:112
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A path may lead to a `black hole`. In a network, a black hole is a router that receives packets for at least one given source/destination pair but does not have an entry inside its forwarding table for this destination. Since it does not know how to reach the destination, the router cannot forward the received packets and must discard them. Any centralized or distributed algorithm that computes forwarding tables must ensure that there are not black holes inside the network.
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../../principles/referencemodels.rst:119
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transport layer entities exchange *segments*
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