Exit Zen
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../../protocols/tcp.rst:550
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graceful connection release, where each TCP user can release its own direction of data transfer after having transmitted all data
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../../glossary.rst:122
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A low-level API originally defined on Berkeley Unix to allow programmers to develop clients and servers.
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../../principles/linkstate.rst:13
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For link-state routing, a network is modeled as a `directed weighted graph`. Each router is a node, and the links between routers are the edges in the graph. A positive weight is associated to each directed edge and routers use the shortest path to reach each destination. In practice, different types of weights can be associated to each directed edge :
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../../principles/reliability.rst:695
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`Pipelining` allows the sender to transmit frames at a higher rate. However this higher transmission rate may overload the receiver. In this case, the frames sent by the sender will not be correctly received by their final destination. The reliable protocols that rely on pipelining allow the sender to transmit `W` unacknowledged frames before being forced to wait for an acknowledgment from the receiving entity.
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../../principles/sharing.rst:764
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A congestion control scheme can be modeled as an algorithm that adapts the transmission rate (:math:`r_i(t)`) of host :math:`i` based on the feedback received from the network. Different types of feedback are possible. The simplest scheme is a binary feedback [CJ1989]_ [Jacobson1988]_ where the hosts simply learn whether the network is congested or not. Some congestion control schemes allow the network to regularly send an allocated transmission rate in Mbps to each host [BF1995]_.
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../../protocols/email.rst:264
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y
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../../protocols/ipv6.rst:543
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``4`` : Parameter Problem. This ICMPv6 message is used to report either the reception of an IPv6 packet with an erroneous header field (code `0`) or an unknown `Next Header` or IP option (codes `1` and `2`). In this case, the message body contains the erroneous IPv6 packet and the first 32 bits of the message body contain a pointer to the error.
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../../protocols/wifi.rst:93
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802.11 devices exchange variable length frames, which have a slightly different structure than the simple frame format used in Ethernet LANs. We review the key parts of the 802.11 frames. Additional details may be found in [IEEE802.11]_ and [Gast2002]_ . An 802.11 frame contains a fixed length header, a variable length payload that may contain up 2324 bytes of user data and a 32 bits CRC. Although the payload can contain up to 2324 bytes, most 802.11 deployments use a maximum payload size of 1500 bytes as they are used in `infrastructure` networks attached to Ethernet LANs. An 802.11 data frame is shown below.
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../../protocols/tcp.rst:551
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abrupt connection release, where either one user closes both directions of data transfer or one TCP entity is forced to close the connection (e.g., because the remote host does not reply anymore or due to lack of resources)
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../../glossary.rst:108
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spoofed packet
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../../principles/linkstate.rst:15
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unit weight. If all links have a unit weight, shortest path routing prefers the paths with the least number of intermediate routers.
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../../principles/sharing.rst:769
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Let us focus on the binary feedback scheme which is the most widely used today. Intuitively, the congestion control scheme should decrease the transmission rate of a host when congestion has been detected in the network, in order to avoid congestion collapse. Furthermore, the hosts should increase their transmission rate when the network is not congested. Otherwise, the hosts would not be able to efficiently utilize the network. The rate allocated to each host fluctuates with time, depending on the feedback received from the network. The figure below illustrates the evolution of the transmission rates allocated to two hosts in our simple network. Initially, two hosts have a low allocation, but this is not efficient. The allocations increase until the network becomes congested. At this point, the hosts decrease their transmission rate to avoid congestion collapse. If the congestion control scheme works well, after some time the allocations should become both fair and efficient.
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../../protocols/email.rst:267
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The example below, from :rfc:`4648`, illustrates the `Base64` encoding.
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../../protocols/ipv6.rst:546
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The `Destination Unreachable` ICMP error message is returned when a packet cannot be forwarded to its final destination. The first four ICMPv6 error messages (type ``1``, codes ``0-3``) are generated by routers while hosts may return code ``4`` when there is no application bound to the corresponding port number.
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../../protocols/wifi.rst:99
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802.11 data frame format
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../../protocols/tcp.rst:555
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The abrupt connection release mechanism is very simple and relies on a single segment having the `RST` bit set. A TCP segment containing the `RST` bit can be sent for the following reasons :
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../../glossary.rst:110
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A packet is said to be spoofed when the sender of the packet has used as source address a different address than its own.
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../../principles/linkstate.rst:16
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weight proportional to the propagation delay on the link. If all link weights are configured this way, shortest path routing uses the paths with the smallest propagation delay.
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../../principles/reliability.rst:703
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The sliding window
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../../principles/sharing.rst:775
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Evolution of the transmission rates
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