Exit Zen
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../../principles/transport.rst:579
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An important difference between the connectionless service and the connection-oriented one is that the transport entities in the latter maintain some state during lifetime of the connection. This state is created when a connection is established and is removed when it is released.
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../../principles/sharing.rst:507
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This name should not be confused with the duration of a transmission slot in slotted ALOHA. In CSMA/CD networks, the slot time is the time during which a collision can occur at the beginning of the transmission of a frame. In slotted ALOHA, the duration of a slot is the transmission time of an entire fixed-size frame.
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../../principles/security.rst:1024
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A detailed explanation of the ECC cryptosystems is outside the scope of this e-book. A simple introduction may be found on `Andrea Corbellini's blog <http://andrea.corbellini.name/2015/05/17/elliptic-curve-cryptography-a-gentle-introduction/>`_. There have been deployments of ECC recently because ECC schemes usually require shorter keys than RSA and consume less CPU.
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../../protocols/bgp.rst:415
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`AS1` prefers the path `AS3:AS0` over all other paths
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../../protocols/email.rst:248
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I
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../../protocols/ethernet.rst:395
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During the computation of the spanning tree, switches discard all received data frames, as at that time the network topology is not guaranteed to be loop-free. Once that topology has been stable for some time, the switches again start to use the MAC learning algorithm to forward data frames. Only the `Root` and `Designated` ports are used to forward data frames. Switches discard all the data frames received on their `Blocked` ports and never forward frames on these ports.
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../../protocols/ipv6.rst:381
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``01`` : if a node does not recognize this header, the packet must be discarded
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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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../../protocols/tcp.rst:332 • ../../protocols/tcp.rst:345
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RTT
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../../glossary.rst:277
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MIME document
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../../principles/network.rst:442
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->R3
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../../principles/reliability.rst:399
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To deal with these types of imperfections, reliable protocols rely on different types of mechanisms. The first problem is transmission errors. Data transmission on a physical link can be affected by the following errors :
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../../principles/sharing.rst:513
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Carrier Sense Multiple Access with Collision Avoidance
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../../protocols/bgp.rst:416
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`AS3` prefers the path `AS4:AS0` over all other paths
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../../protocols/email.rst:248
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25
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../../protocols/ethernet.rst:397
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Switches, ports and links can fail in a switched Ethernet network. When a failure occurs, the switches must be able to recompute the spanning tree to recover from the failure. The `Spanning Tree Protocol` relies on regular transmissions of the `BPDUs` to detect these failures. A `BPDU` contains two additional fields : the `Age` of the `BPDU` and the `Maximum Age`. The `Age` contains the amount of time that has passed since the root switch initially originated the `BPDU`. The root switch sends its `BPDU` with an `Age` of zero and each switch that computes its own `BPDU` increments its `Age` by one. The `Age` of the `BPDUs` stored on a switch's table is also incremented every second. A `BPDU` expires when its `Age` reaches the `Maximum Age`. When the network is stable, this does not happen as `BPDU` s are regularly sent by the `root` switch and downstream switches. However, if the `root` fails or the network becomes partitioned, `BPDU` will expire and switches will recompute their own `BPDU` and restart the `Spanning Tree Protocol`. Once a topology change has been detected, the forwarding of the data frames stops as the topology is not guaranteed to be loop-free. Additional details about the reaction to failures may be found in [IEEE802.1d]_.
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../../protocols/ipv6.rst:382
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``10`` (resp. ``11``) : if a node does not recognize this header, it must return a control packet (ICMP, see later) back to the source (resp. except if the destination was a multicast address)
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../../protocols/ethernet.rst:373
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Port state
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../../protocols/tcp.rst:332 • ../../protocols/tcp.rst:345
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Maximum Throughput
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../../glossary.rst:279
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A MIME document is a document, encoded by using the :term:`MIME` format.
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