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../../principles/transport.rst:536
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To deal with these issues, the transport layer includes several mechanisms that depend on the service that it provides. It interacts with both the applications and the underlying network layer.
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../../principles/sharing.rst:436
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To better understand these collisions, it is useful to analyze what would be the worst collision on a shared bus network. Let us consider a wire with two hosts attached at both ends, as shown in the figure below. Host A starts to transmit its frame and its electrical signal is propagated on the cable. Its propagation time depends on the physical length of the cable and the speed of the electrical signal. Let us use :math:`\tau` to represent this propagation delay in seconds. Slightly less than :math:`\tau` seconds after the beginning of the transmission of A's frame, B decides to start transmitting its own frame. After :math:`\epsilon` seconds, B senses A's frame, detects the collision and stops transmitting. The beginning of B's frame travels on the cable until it reaches host A. Host A can thus detect the collision at time :math:`\tau-\epsilon+\tau \approx 2\times\tau`. An important point to note is that a collision can only occur during the first :math:`2\times\tau` seconds of its transmission. If a collision did not occur during this period, it cannot occur afterwards since the transmission channel is busy after :math:`\tau` seconds and CSMA/CD hosts sense the transmission channel before transmitting their frame.
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../../principles/security.rst:977
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Mallory generates a secret integer, :math:`m` and sends :math:`M=g^{m} \mod p` to Bob
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../../exercises/ipv6.rst:888
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The ``pingall`` command reveals that there is a problem in this network.
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../../protocols/bgp.rst:369
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insert a low `local-pref` attribute in the routes learned from a provider
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../../protocols/email.rst:244 • ../../protocols/email.rst:246
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6
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../../protocols/ethernet.rst:368
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To determine the state of its other ports, the switch compares its own `BPDU` with the last `BPDU` received on each port. Note that the comparison is done by using the `BPDUs` and not the `root priority vectors`. If the switch's `BPDU` is better than the last `BPDU` of this port, the port becomes a `Designated` port. Otherwise, the port becomes a `Blocked` port.
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../../protocols/ipv6.rst:349
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For example, an IPv6 packet that contains an TCP segment would appear as shown in the figure below.
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../../protocols/ethernet.rst:353
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Bandwidth
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../../protocols/tcp.rst:270
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`sending buffer` : a buffer used to store all unacknowledged data
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../../glossary.rst:291
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An :term:`ISO` standard that defines codes to represent countries and their subdivisions. See http://www.iso.org/iso/country_codes.htm
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../../principles/network.rst:373 • ../../principles/network.rst:412 • ../../principles/network.rst:414 • ../../principles/network.rst:424 • ../../principles/network.rst:434 • ../../principles/network.rst:444
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1
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../../principles/reliability.rst:336
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data frames carrying a SDU
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../../principles/transport.rst:542
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Interactions between the transport layer, its user, and its network layer provider
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../../principles/sharing.rst:443
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The worst collision on a shared bus
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../../principles/security.rst:978
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Bob chooses a secret integer and sends :math:`B=g^{b} \mod p` to Mallory
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../../exercises/ipv6.rst:898
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We can analyze this configuration problem in more details by using ``traceroute6``. The loop appears clearly.
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../../protocols/bgp.rst:371
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With such an import filter, the routers of a domain always prefer to reach destinations via their customers whenever such a route exists. Otherwise, they prefer to use `shared-cost` peering relationships and they only send packets via their providers when they do not know any alternate route. A consequence of setting the `local-pref` attribute like this is that Internet paths are often asymmetrical. Consider for example the internetwork shown in the figure below.
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../../protocols/email.rst:244
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G
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../../protocols/ethernet.rst:370
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The state of each port is important when considering the transmission of `BPDUs`. The root switch regularly sends its own `BPDU` over all of its (`Designated`) ports. This `BPDU` is received on the `Root` port of all the switches that are directly connected to the `root switch`. Each of these switches computes its own `BPDU` and sends this `BPDU` over all its `Designated` ports. These `BPDUs` are then received on the `Root` port of downstream switches, which then compute their own `BPDU`, etc. When the network topology is stable, switches send their own `BPDU` on all their `Designated` ports, once they receive a `BPDU` on their `Root` port. No `BPDU` is sent on a `Blocked` port. Switches listen for `BPDUs` on their `Blocked` and `Designated` ports, but no `BPDU` should be received over these ports when the topology is stable. The utilization of the ports for both `BPDUs` and data frames is summarized in the table below.
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