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../../exercises/sockets.rst:280
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Sending a message to a remote peer using its IPv6 address
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../../principles/referencemodels.rst:120
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application layer entities exchange *SDUs*
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../../exercises/reliability.rst:65
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all errors that affect a sequence of bits which is shorter than the length of the CRC
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../../exercises/network.rst:299
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Some hosts need to be multihomed, i.e. attached to two different network nodes as shown in the figure below.
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../../exercises/sockets.rst:284
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Now that we created an IPv6 socket, we can use it to reach another program if we know its IPv6 address. IPv6 addresses have a human-readable format that can be represented as a string of characters. The details of IPv6 addresses are out of scope of this section but here are some examples :
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../../principles/naming.rst:139
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Footnotes
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../../principles/referencemodels.rst:125
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Reference models
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../../principles/reliability.rst:106
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With the above transmission scheme, a bit is transmitted by setting the voltage on the electrical cable to a specific value during some period of time. We have seen that due to electromagnetic interference, the voltage measured by the receiver can differ from the voltage set by the transmitter. This is the main cause of transmission errors. However, this is not the only type of problem that can occur. Besides defining the voltages for bits `0` and `1`, the above transmission scheme also specifies the duration of each bit. If one million bits are sent every second, then each bit lasts 1 microsecond. On each host, the transmission (resp. the reception) of each bit is triggered by a local clock having a 1 MHz frequency. These clocks are the second source of problems when transmitting bits over a wire. Although the two clocks have the same specification, they run on different hosts, possibly at a different temperature and with a different source of energy. In practice, it is possible that the two clocks do not operate at exactly the same frequency. Assume that the clock of the transmitting host operates at exactly 1000000 Hz while the receiving clock operates at 999999 Hz. This is a very small difference between the two clocks. However, when using the clock to transmit bits, this difference is important. With its 1000000 Hz clock, the transmitting host will generate one million bits during a period of one second. During the same period, the receiving host will sense the wire 999999 times and thus will receive one bit less than the bits originally transmitted. This small difference in clock frequencies implies that bits can "disappear" during their transmission on an electrical cable. This is illustrated in the figure below.
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../../exercises/network.rst:323
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Would this network work correctly with port-forwarding tables if :
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../../exercises/sockets.rst:283
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The ``::1`` IPv6 address identifies the computer on which the current program is running.
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../../principles/naming.rst:140
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The :term:`hosts.txt` file is not maintained anymore. A historical snapshot from April 1984 is available from http://ftp.univie.ac.at/netinfo/netinfo/hosts.txt
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../../principles/referencemodels.rst:128
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Two reference models have been successful in the networking community : the OSI reference model and the TCP/IP reference model. We discuss them briefly in this section.
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../../principles/reliability.rst:128
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A similar reasoning applies when the clock of the sending host is slower than the clock of the receiving host. In this case, the receiver will sense more bits than the bits that have been transmitted by the sender. This is illustrated in the figure below where the second bit received on the right was not transmitted by the left host.
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../../exercises/network.rst:325
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Host `A` uses the same flat address for both links.
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../../exercises/sockets.rst:284
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The ``2001:6a8:308f:9:0:82ff:fe68:e520`` IPv6 address identifies the computer serving the ``https://beta.computer-networking.info`` website.
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../../principles/naming.rst:142
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See http://www.donelan.com/dnstimeline.html for a time line of DNS related developments.
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../../principles/referencemodels.rst:132
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The TCP/IP reference model
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../../exercises/dns.rst:112
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Footnotes
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../../exercises/reliability.rst:74
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Discussion questions
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../../exercises/network.rst:326
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Host `A` uses a different flat address on each of its links
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