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134 ../../principles/reliability.rst:468 • ../../principles/reliability.rst:485

	English 100 3/10000 · 3
134 ../../principles/sharing.rst:817

	English The text above describes the basic operation of a Token Ring network when all stations work correctly. Unfortunately, a real Token Ring network must be able to handle various types of anomalies and this increases the complexity of Token Ring stations. We briefly list the problems and outline their solutions below. A detailed description of the operation of Token Ring stations may be found in [IEEE802.5]_. The first problem is when all the stations attached to the network start. One of them must bootstrap the network by sending the first token. For this, all stations implement a distributed election mechanism that is used to select the `Monitor`. Any station can become a `Monitor`. The `Monitor` manages the Token Ring network and ensures that it operates correctly. Its first role is to introduce a delay of 24 bit transmission times to ensure that the token can travel smoothly on the ring. Second, the `Monitor` sends the first token on the ring. It must also verify that the token passes regularly. According to the Token Ring standard [IEEE802.5]_, a station cannot retain the token to transmit data frames for a duration longer than the `Token Holding Time` (THT) (slightly less than 10 milliseconds). On a network containing `N` stations, the `Monitor` must receive the token at least every :math:`N \times THT` seconds. If the `Monitor` does not receive a token during such a period, it cuts the ring for some time and then re-initializes the ring and sends a token. 1482/10000 · 1482
134 ../../protocols/bgp.rst:475

	English See http://as-rank.caida.org/ for an analysis of the interconnections between domains based on measurements collected in the global Internet. 142/10000 · 142
134 ../../protocols/email.rst:254

	English t 1/10000 · 1
134 ../../protocols/ipv6.rst:429

	English If a router receives a packet that is too long to be forwarded, the packet is dropped and the router returns an ICMPv6 message to inform the sender of the problem. The sender can then either fragment the packet or perform Path MTU discovery. In IPv6, packet fragmentation is performed only by the source by using IPv6 options. 326/10000 · 326
134 ../../protocols/wifi.rst:9

	English In the 1970s, after the first experiments with ALOHANet, interest in wireless networks grew. Many experiments were done on and outside the ARPANet. One of these experiments was the `first mobile phone <http://news.bbc.co.uk/2/hi/programmes/click_online/8639590.stm>`_ , which was developed and tested in 1973. This experimental mobile phone was the starting point for the first generation analog mobile phones. Given the growing demand for mobile phones, it was clear that the analog mobile phone technology was not sufficient to support a large number of users. To support more users and new services, researchers in several countries worked on the development of digital mobile telephones. In 1987, several European countries decided to develop the standards for a common cellular telephone system across Europe : the `Global System for Mobile Communications` (GSM). Since then, the standards have evolved and more than three billion users are connected to GSM networks today. 979/10000 · 979
134 ../../protocols/tcp.rst:400

	English Disambiguating round-trip-time measurements with the :rfc:`1323` timestamp option 81/10000 · 81
134 ../../principles/transport.rst:780

	English The first point which is common between the two layers is that both use CRCs or checksums to detect transmission errors. Each segment contains a CRC/checksum which is computed over the entire segment (header and payload) by the sender and inserted in the header. The receiver recomputes the CRC/checksum for each received segment and discards all segments with an invalid CRC. 376/10000 · 376
135 ../../bibliography.rst:341

	English Sklower, K. 1989. `Improving the efficiency of the OSI checksum calculation <http://doi.acm.org/10.1145/74681.74684>`_. SIGCOMM Computer Communication Review 19, 5 (Oct. 1989), 32-43. 183/10000 · 183
135 ../../glossary.rst:53

	English Problem-based learning is a teaching approach that relies on problems. 70/10000 · 70
135 ../../principles/dv.rst:117

	English Assume that router `A` is the first to send its distance vector `[A=0]`. 72/10000 · 72
135 ../../principles/reliability.rst:469 • ../../principles/reliability.rst:486

	English 111 3/10000 · 3
135 ../../principles/sharing.rst:819

	English Several other anomalies may occur in a Token Ring network. For example, a station could capture a token and be powered off before having resent the token. Another station could have captured the token, sent its data frame and be powered off before receiving all of its data frame. In this case, the bit string corresponding to the end of a frame would remain in the ring without being removed by its sender. Several techniques are defined in [IEEE802.5]_ to allow the `Monitor` to handle all these problems. If unfortunately, the `Monitor` fails, another station will be elected to become the new `Monitor`. 607/10000 · 607
135 ../../protocols/bgp.rst:478

	English Two routers that are attached to the same IXP exchange packets only when the owners of their domains have an economical incentive to exchange packets on this IXP. Usually, a router on an IXP is only able to exchange packets with a small fraction of the routers that are present on the same IXP. 294/10000 · 294
135 ../../protocols/email.rst:254

	English 62 2/10000 · 2
135 ../../protocols/ipv6.rst:433

	English In IPv6, fragmentation is performed exclusively by the source host and relies on the fragmentation header. This 64 bits header is composed of six fields : 154/10000 · 154
135 ../../protocols/wifi.rst:13

	English While most of the frequency ranges of the radio spectrum are reserved for specific applications and require a special license, there are a few exceptions. These exceptions are known as the `Industrial, Scientific and Medical <http://en.wikipedia.org/wiki/ISM_band>`_ (ISM) radio bands. These bands can be used for industrial, scientific and medical applications without requiring a license from the regulator. For example, some radio-controlled models use the 27 MHz ISM band and some cordless telephones operate in the 915 MHz ISM. In 1985, the 2.400-2.500 GHz band was added to the list of ISM bands. This frequency range corresponds to the frequencies that are emitted by microwave ovens. Sharing this band with licensed applications would have likely caused interference, given the large number of microwave ovens that are used. Despite the risk of interference with microwave ovens, the opening of the 2.400-2.500 GHz allowed the networking industry to develop several wireless network techniques to allow computers to exchange data without using cables. In this section, we discuss in more detail the most popular one, i.e. the WiFi [IEEE802.11]_ family of wireless networks. Other wireless networking techniques such as `BlueTooth <http://en.wikipedia.org/wiki/BlueTooth>`_ or `HiperLAN <http://en.wikipedia.org/wiki/HiperLAN>`_ use the same frequency range. 1365/10000 · 1365
135 ../../protocols/tcp.rst:402

	English Once the round-trip-time measurements have been collected for a given TCP connection, the TCP entity must compute the retransmission timeout. As the round-trip-time measurements may change during the lifetime of a connection, the retransmission timeout may also change. At the beginning of a connection [#ftcbtouch]_, the TCP entity that sends a `SYN` segment does not know the round-trip-time to reach the remote host and the initial retransmission timeout is usually set to 3 seconds :rfc:`2988`. 498/10000 · 498
135 ../../principles/transport.rst:782

	English Reliable transport protocols also use sequence numbers and acknowledgment numbers. While reliable protocols in the datalink layer use one sequence number per frame, reliable transport protocols consider all the data transmitted as a stream of bytes. In these protocols, the sequence number placed in the segment header corresponds to the position of the first byte of the payload in the bytestream. This sequence number allows detecting losses but also enables the receiver to reorder the out-of-sequence segments. This is illustrated in the figure below. 555/10000 · 555
136 ../../glossary.rst:244

	English POP 3/10000 · 3

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