Exit Zen
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../../principles/transport.rst:544
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We have already described in the datalink layers mechanisms to deal with data losses and transmission errors. These techniques are also used in the transport layer.
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../../principles/sharing.rst:446
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Furthermore, on the wired networks where CSMA/CD is used, collisions are almost the only cause of transmission errors that affect frames. Transmission errors that only affect a few bits inside a frame seldom occur in these wired networks. For this reason, the designers of CSMA/CD chose to completely remove the acknowledgment frames in the datalink layer. When a host transmits a frame, it verifies whether its transmission has been affected by a collision. If not, given the negligible Bit Error Ratio of the underlying network, it assumes that the frame was received correctly by its destination. Otherwise the frame is retransmitted after some delay.
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../../principles/security.rst:979
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Mallory computes :math:`S_{A}=A^{m} \mod p` and :math:`S_{B}=B^{m} \mod p`
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../../exercises/ipv6.rst:919
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On host ``b``, the problem is different. The packets that it sends towards host ``a`` do not seem to go beyond router ``r3``.
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../../protocols/bgp.rst:377
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Asymmetry of Internet paths
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../../protocols/email.rst:244
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../../protocols/ethernet.rst:373
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Port state
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../../protocols/ipv6.rst:358
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However, the `Next header` has broader usages than simply indicating the transport protocol which is responsible for the packet payload. An IPv6 packet can contain a chain of headers and the last one indicates the transport protocol that is responsible for the packet payload. Supporting a chain of headers is a clever design from an extensibility viewpoint. As we will see, this chain of headers has several usages.
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../../protocols/ethernet.rst:355
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10 Mbps
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../../protocols/tcp.rst:274
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The original TCP specification can be summarized as a transport protocol that provides a byte stream service and uses `go-back-n` with a `selective-repeat` reception strategy.
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../../glossary.rst:297
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An Internet Service Provider, i.e. a network that provides Internet access to its clients.
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../../principles/network.rst:375 • ../../principles/network.rst:377
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2
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../../principles/reliability.rst:339
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These two types of frames can be distinguished by dividing the frame in two parts :
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../../principles/transport.rst:548
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Connectionless transport
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../../principles/sharing.rst:449
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Removing acknowledgments is an interesting optimization as it reduces the number of frames that are exchanged on the network and the number of frames that need to be processed by the hosts. However, to use this optimization, we must ensure that all hosts will be able to detect all the collisions that affect their frames. The problem is important for short frames. Let us consider two hosts, A and B, that are sending a small frame to host C as illustrated in the figure below. If the frames sent by A and B are very short, the situation illustrated below may occur. Hosts A and B send their frame and stop transmitting (point `(1)`). When the two short frames arrive at the location of host C, they collide and host C cannot decode them (point `(2)`). The two frames are absorbed by the ends of the wire. Neither host A nor host B have detected the collision. They both consider their frame to have been received correctly by its destination.
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../../principles/security.rst:980
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Alice computes :math:`S_{A}=M^{a} \mod p` and uses this key to communicate with Mallory (acting as Bob)
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../../exercises/ipv6.rst:933
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To debug this problem, let us look at the forwarding table of ``r3``. This router forwards the packets sent to host ``a`` to router ``r1`` that is directly connected to host ``a``.
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../../protocols/bgp.rst:379
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Consider in this internetwork the routes available inside `AS1` to reach `AS5`. `AS1` learns the `AS4:AS6:AS7:AS5` path from `AS4`, the `AS3:AS8:AS5` path from `AS3` and the `AS2:AS5` path from `AS2`. The first path is chosen since it was learned from a customer. `AS5` on the other hand receives three paths towards `AS1` via its providers. It may select any of these paths to reach `AS1` , depending on how it prefers one provider over the others.
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../../protocols/email.rst:244
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X
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../../protocols/ethernet.rst:373
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Receives BPDUs
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