<?xml version="1.0" encoding="UTF-8"?>
<xliff xmlns="urn:oasis:names:tc:xliff:document:1.1" version="1.1">
  <file original="NoName" source-language="en" datatype="plaintext" target-language="en">
    <body>
      <trans-unit xml:space="preserve" approved="no" id="e7152480583fdc70" weblate-flags="read-only">
        <source>Reliable transfer</source>
        <target state="translated">Reliable transfer</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">7</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="ea725087c218738b" weblate-flags="read-only">
        <source>Open questions</source>
        <target state="translated">Open questions</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">11</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="ad51e44368916166" weblate-flags="read-only">
        <source>Consider a `b` bits per second link between two hosts that has a propagation delay of `t` seconds. Derive a formula that computes the time elapsed between the transmission of the first bit of a `d` bytes frame from a sending host and the reception of the last bit of this frame on the receiving host.</source>
        <target state="translated">Consider a `b` bits per second link between two hosts that has a propagation delay of `t` seconds. Derive a formula that computes the time elapsed between the transmission of the first bit of a `d` bytes frame from a sending host and the reception of the last bit of this frame on the receiving host.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">13</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="a732c3a52664e4c9" weblate-flags="read-only">
        <source>Transmission links have sometimes different upstream and downstream bandwidths. A typical example are access networks that use ADSL (Asymmetric Digital Subscriber Lines). Consider two hosts connected via an ADSL link having an upstream bandwidth of 1 Mbps and a downstream bandwidth of 50 Mbps. The propagation delay between the two hosts is 10 milliseconds. What is the maximum throughput, expressed in frames/second, that the alternating bit protocol can obtain on this link if each data frame has a length of 125 bytes and acknowledgments are 25 bytes long. Same question if the protocol is modified to support 1500 bytes long data frames.</source>
        <target state="translated">Transmission links have sometimes different upstream and downstream bandwidths. A typical example are access networks that use ADSL (Asymmetric Digital Subscriber Lines). Consider two hosts connected via an ADSL link having an upstream bandwidth of 1 Mbps and a downstream bandwidth of 50 Mbps. The propagation delay between the two hosts is 10 milliseconds. What is the maximum throughput, expressed in frames/second, that the alternating bit protocol can obtain on this link if each data frame has a length of 125 bytes and acknowledgments are 25 bytes long. Same question if the protocol is modified to support 1500 bytes long data frames.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">15</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="671ef67dc127fcd7" weblate-flags="read-only">
        <source>How would you set the duration of the retransmission timer in the alternating bit protocol ?</source>
        <target state="translated">How would you set the duration of the retransmission timer in the alternating bit protocol ?</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">17</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="e81e94f1ab2feaea" weblate-flags="read-only">
        <source>A version of the Alternating Bit Protocol supporting variable length frames uses a header that contains the following fields :</source>
        <target state="translated">A version of the Alternating Bit Protocol supporting variable length frames uses a header that contains the following fields :</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">19</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="acfd9e9e8f98774c" weblate-flags="read-only">
        <source>a `number` (0 or 1)</source>
        <target state="translated">a `number` (0 or 1)</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">21</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="ad8d202c44e7fd0a" weblate-flags="read-only">
        <source>a `length` field that indicates the length of the data</source>
        <target state="translated">a `length` field that indicates the length of the data</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">22</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="a84b234b6232fe5c" weblate-flags="read-only">
        <source>a Cyclic Redundancy Check (`CRC`)</source>
        <target state="translated">a Cyclic Redundancy Check (`CRC`)</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">23</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="f6e595b03a7f2258" weblate-flags="read-only">
        <source>To speedup the transmission of the frames, a student proposes to compute the CRC over the data part of the frame but not over the header. What do you think of this proposed solution ?</source>
        <target state="translated">To speedup the transmission of the frames, a student proposes to compute the CRC over the data part of the frame but not over the header. What do you think of this proposed solution ?</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">25</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="aaed863c300fb251" weblate-flags="read-only">
        <source>Derive a mathematical expression that provides the `goodput`, i.e. the amount of payload bytes that have been transmitted during a period of time, achieved by the Alternating Bit Protocol assuming that :</source>
        <target state="translated">Derive a mathematical expression that provides the `goodput`, i.e. the amount of payload bytes that have been transmitted during a period of time, achieved by the Alternating Bit Protocol assuming that :</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">27</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="8bb3b9213582c0f5" weblate-flags="read-only">
        <source>Each frame contains `D` bytes of data and `c` bytes of control information</source>
        <target state="translated">Each frame contains `D` bytes of data and `c` bytes of control information</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">29</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="517fa75ca5f02ebb" weblate-flags="read-only">
        <source>Each acknowledgment contains `c` bytes of control information</source>
        <target state="translated">Each acknowledgment contains `c` bytes of control information</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">30</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="4d111b76cb1cebb4" weblate-flags="read-only">
        <source>The bandwidth of the two directions of the link is set to `B` bits per second</source>
        <target state="translated">The bandwidth of the two directions of the link is set to `B` bits per second</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">31</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="43044825467e548d" weblate-flags="read-only">
        <source>The delay between the two hosts is `s` seconds in both directions</source>
        <target state="translated">The delay between the two hosts is `s` seconds in both directions</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">32</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="44def8e00fab1403" weblate-flags="read-only">
        <source>there are no transmission errors</source>
        <target state="translated">there are no transmission errors</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">33</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="0a67c401468d35b6" weblate-flags="read-only">
        <source>Consider a go-back-n sender and a go-back receiver that are directly connected with a 10 Mbps link that has a propagation delay of 100 milliseconds. Assume that the retransmission timer is set to three seconds. If the window has a length of 4 frames, draw a time-sequence diagram showing the transmission consisting of 10 data frames (each frame contains 10000 bits):</source>
        <target state="translated">Consider a go-back-n sender and a go-back receiver that are directly connected with a 10 Mbps link that has a propagation delay of 100 milliseconds. Assume that the retransmission timer is set to three seconds. If the window has a length of 4 frames, draw a time-sequence diagram showing the transmission consisting of 10 data frames (each frame contains 10000 bits):</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">35</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="f515d0d76dfe2a31" weblate-flags="read-only">
        <source>when there are no losses</source>
        <target state="translated">when there are no losses</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">37</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="ba99a3db1114a9ea" weblate-flags="read-only">
        <source>when the third and seventh frames are lost</source>
        <target state="translated">when the third and seventh frames are lost</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">38</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="43f6fcf6023fcd7a" weblate-flags="read-only">
        <source>when every second acknowledgment is discarded due to transmission errors</source>
        <target state="translated">when every second acknowledgment is discarded due to transmission errors</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">39</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="dfffc1fccb9ece57" weblate-flags="read-only">
        <source>Same question when using selective repeat instead of go-back-n. Note that the answer is not necessarily the same.</source>
        <target state="translated">Same question when using selective repeat instead of go-back-n. Note that the answer is not necessarily the same.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">41</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="32b9b9b26dcbfee0" weblate-flags="read-only">
        <source>Practice</source>
        <target state="translated">Practice</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">45</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="2a81ece8ff05d384" weblate-flags="read-only">
        <source>Reliable protocols depend on error detection algorithms to detect transmission errors. The following questions will reinforce your understanding of these algorithms.</source>
        <target state="translated">Reliable protocols depend on error detection algorithms to detect transmission errors. The following questions will reinforce your understanding of these algorithms.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">47</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="3de916ab38a31d48" weblate-flags="read-only">
        <source>Reliable protocols rely on different types of checksums to verify whether frames have been affected by transmission errors. The most frequently used checksums are :</source>
        <target state="translated">Reliable protocols rely on different types of checksums to verify whether frames have been affected by transmission errors. The most frequently used checksums are :</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">49</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="f6a46967ac161458" weblate-flags="read-only">
        <source>the Internet checksum used by UDP, TCP and other Internet protocols which is defined in :rfc:`1071` and implemented in various libraries.</source>
        <target state="translated">the Internet checksum used by UDP, TCP and other Internet protocols which is defined in :rfc:`1071` and implemented in various libraries.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">51</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="6215f85de922b2aa" weblate-flags="read-only">
        <source>the 16 bits or the 32 bits Cyclical Redundancy Checks (CRC) that are often used on disks, in zip archives and in datalink layer protocols. See http://rosettacode.org/wiki/CRC-32 for CRC-32 implementations in various languages.</source>
        <target state="translated">the 16 bits or the 32 bits Cyclical Redundancy Checks (CRC) that are often used on disks, in zip archives and in datalink layer protocols. See http://rosettacode.org/wiki/CRC-32 for CRC-32 implementations in various languages.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">52</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="f5ba677179d704b4" weblate-flags="read-only">
        <source>the Fletcher checksum [Fletcher1982]_, see https://en.wikipedia.org/wiki/Fletcher%27s_checksum for implementation details.</source>
        <target state="translated">the Fletcher checksum [Fletcher1982]_, see https://en.wikipedia.org/wiki/Fletcher%27s_checksum for implementation details.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">53</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="656a0ff056decde4" weblate-flags="read-only">
        <source>By using your knowledge of the Internet checksum, can you find a transmission error that will not be detected by these checksums?</source>
        <target state="translated">By using your knowledge of the Internet checksum, can you find a transmission error that will not be detected by these checksums?</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">55</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="8cdcb314dcda003e" weblate-flags="read-only">
        <source>The Cyclic Redundancy Checks (CRCs) are efficient error detection codes that are able to detect :</source>
        <target state="translated">The Cyclic Redundancy Checks (CRCs) are efficient error detection codes that are able to detect :</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">57</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="77e0c17bd2bfe0b3" weblate-flags="read-only">
        <source>all errors that affect an odd number of bits</source>
        <target state="translated">all errors that affect an odd number of bits</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">59</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="0df19d844ad3bb0d" weblate-flags="read-only">
        <source>all errors that affect a sequence of bits which is shorter than the length of the CRC</source>
        <target state="translated">all errors that affect a sequence of bits which is shorter than the length of the CRC</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">60</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="fc19b9f6d2e0e2ac" weblate-flags="read-only">
        <source>Implement a small software that computes the CRC-32 for a text file. Then, modify the contents of the file to change an even number of bits or an odd number of bits inside the file. When modifying the file, remember that an ASCII file is composed of 8 bits characters that are encoded by using the ASCII table that you can find at : http://en.wikipedia.org/wiki/ASCII . You can also write a small program that produces binary files that are a small variation of each other.</source>
        <target state="translated">Implement a small software that computes the CRC-32 for a text file. Then, modify the contents of the file to change an even number of bits or an odd number of bits inside the file. When modifying the file, remember that an ASCII file is composed of 8 bits characters that are encoded by using the ASCII table that you can find at : http://en.wikipedia.org/wiki/ASCII . You can also write a small program that produces binary files that are a small variation of each other.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">62</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="60b59a211f714e25" weblate-flags="read-only">
        <source>Checksums and CRCs should not be confused with secure hash functions such as MD5 defined in :rfc:`1321` or SHA-1 described in :rfc:`4634`. Secure hash functions are used to ensure that files or sometimes frames/packets/segments have not been modified. Secure hash functions aim at detecting malicious changes while checksums and CRCs only detect random transmission errors. Use the `shasum &lt;http://linux.die.net/man/1/shasum&gt;`_ or `md5sum &lt;http://linux.die.net/man/1/md5sum&gt;`_ programs on Linux to perform the same tests as above.</source>
        <target state="translated">Checksums and CRCs should not be confused with secure hash functions such as MD5 defined in :rfc:`1321` or SHA-1 described in :rfc:`4634`. Secure hash functions are used to ensure that files or sometimes frames/packets/segments have not been modified. Secure hash functions aim at detecting malicious changes while checksums and CRCs only detect random transmission errors. Use the `shasum &lt;http://linux.die.net/man/1/shasum&gt;`_ or `md5sum &lt;http://linux.die.net/man/1/md5sum&gt;`_ programs on Linux to perform the same tests as above.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">64</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="ef6154c2f011bd25" weblate-flags="read-only">
        <source>Discussion questions</source>
        <target state="translated">Discussion questions</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">68</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="ee2d61dc4759da06" weblate-flags="read-only">
        <source>Consider two high-end servers connected back-to-back by using a 10 Gbps interface. If the delay between the two servers is one millisecond, what is the throughput that can be achieved by a reliable protocol that is using 10,000 bits frames and a window of</source>
        <target state="translated">Consider two high-end servers connected back-to-back by using a 10 Gbps interface. If the delay between the two servers is one millisecond, what is the throughput that can be achieved by a reliable protocol that is using 10,000 bits frames and a window of</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">70</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="fcb58d2637233fe2" weblate-flags="read-only">
        <source>one frame</source>
        <target state="translated">one frame</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">72</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="2710cb44c5b01416" weblate-flags="read-only">
        <source>ten frames</source>
        <target state="translated">ten frames</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">73</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="ab40f0c248e8a60a" weblate-flags="read-only">
        <source>hundred frames</source>
        <target state="translated">hundred frames</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">74</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="0a9341e6c8d8c4fb" weblate-flags="read-only">
        <source>Is it possible for a go-back-n receiver to inter-operate with a selective-repeat sender ? Justify your answer.</source>
        <target state="translated">Is it possible for a go-back-n receiver to inter-operate with a selective-repeat sender ? Justify your answer.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">76</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="14b67d50fcff5895" weblate-flags="read-only">
        <source>Is it possible for a selective-repeat receiver to inter-operate with a go-back-n sender ? Justify your answer.</source>
        <target state="translated">Is it possible for a selective-repeat receiver to inter-operate with a go-back-n sender ? Justify your answer.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">78</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="7f78d26b7c273c5a" weblate-flags="read-only">
        <source>A go-back-n sender has sent :math:`2^n` data frames. All the frames have been received correctly and in-order by the receiver, but all the returned acknowledgments have been lost. Show by using a time sequence diagram (e.g. by considering a window of four frames) what happens in this case. Can you fix the problem on the go-back-n sender ?</source>
        <target state="translated">A go-back-n sender has sent :math:`2^n` data frames. All the frames have been received correctly and in-order by the receiver, but all the returned acknowledgments have been lost. Show by using a time sequence diagram (e.g. by considering a window of four frames) what happens in this case. Can you fix the problem on the go-back-n sender ?</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">82</context>
        </context-group>
      </trans-unit>
      <trans-unit xml:space="preserve" approved="no" id="0752ee9fa7e71a9b" weblate-flags="read-only">
        <source>Same question as above, but assume now that both the sender and the receiver implement selective repeat. Note that the answer can be different from the above question.</source>
        <target state="translated">Same question as above, but assume now that both the sender and the receiver implement selective repeat. Note that the answer can be different from the above question.</target>
        <context-group name="" purpose="location">
          <context context-type="sourcefile">../../exercises/reliability.rst</context>
          <context context-type="linenumber">84</context>
        </context-group>
      </trans-unit>
    </body>
  </file>
</xliff>
