cnp3-ebook - English @ Weblate

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124 ../../principles/sharing.rst:771

	English While the basic principles of the Token Ring are simple, there are several subtle implementation details that add complexity to Token Ring networks. To understand these details let us analyze the operation of a Token Ring interface on a station. A Token Ring interface serves three different purposes. Like other LAN interfaces, it must be able to send and receive frames. In addition, a Token Ring interface is part of the ring, and as such, it must be able to forward the electrical signal that passes on the ring even when its station is powered off. 553/10000 · 553
124 ../../principles/transport.rst:745

	English Thanks to the three way handshake, transport entities avoid duplicate transport connections. This is illustrated by considering the three scenarios below. 154/10000 · 154
124 ../../protocols/bgp.rst:438

	English The second guideline also corresponds to economic preferences. Since a provider earns money when sending packets to one of its customers, it makes sense to prefer such customer learned routes over routes learned from providers. [GR2001]_ also shows that BGP convergence is guaranteed even if an AS associates the same preference to routes learned from a `shared-cost` peer and routes learned from a customer. 408/10000 · 408
124 ../../protocols/email.rst:252

	English 27 2/10000 · 2
124 ../../protocols/ipv6.rst:407

	English 802.15.4 8/10000 · 8
124 ../../protocols/ethernet.rst:397

	English 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]_. 1260/10000 · 1260
124 ../../protocols/tcp.rst:350

	English 17 Gbps 7/10000 · 7
124 ../../principles/reliability.rst:458

	English Besides framing, datalink layers also include mechanisms to detect and sometimes even recover from transmission errors. To allow a receiver to notice transmission errors, a sender must add some redundant information as an `error detection` code to the frame sent. This `error detection` code is computed by the sender on the frame that it transmits. When the receiver receives a frame with an error detection code, it recomputes it and verifies whether the received `error detection code` matches the computed `error detection code`. If they match, the frame is considered to be valid. Many error detection schemes exist and entire books have been written on the subject. A detailed discussion of these techniques is outside the scope of this book, and we will only discuss some examples to illustrate the key principles. 821/10000 · 821
125 ../../bibliography.rst:324

	English Ross, F., `An overview of FDDI: The fiber distributed data interface <https://dx.doi.org/10.1109/49.44552>`_, IEEE J. Selected Areas in Comm., vol. 7, no. 7, pp. 1043-1051, Sept. 1989 183/10000 · 183
125 ../../glossary.rst:207

	English The Network File System is defined in :rfc:`1094` 49/10000 · 49
125 ../../principles/dv.rst:13

	English `R[d].link` is the outgoing link that the router uses to forward packets towards destination `d` 96/10000 · 96
125 ../../principles/reliability.rst:460

	English To understand `error detection codes`, let us consider two devices that exchange bit strings containing `N` bits. To allow the receiver to detect a transmission error, the sender converts each string of `N` bits into a string of `N+r` bits. Usually, the `r` redundant bits are added at the beginning or the end of the transmitted bit string, but some techniques interleave redundant bits with the original bits. An `error detection code` can be defined as a function that computes the `r` redundant bits corresponding to each string of `N` bits. The simplest error detection code is the parity bit. There are two types of parity schemes : even and odd parity. With the `even` (resp. `odd`) parity scheme, the redundant bit is chosen so that an even (resp. odd) number of bits are set to `1` in the transmitted bit string of `N+r` bits. The receiver can easily recompute the parity of each received bit string and discard the strings with an invalid parity. The parity scheme is often used when 7-bit characters are exchanged. In this case, the eighth bit is often a parity bit. The table below shows the parity bits that are computed for bit strings containing three bits. 1172/10000 · 1172
125 ../../principles/sharing.rst:773

	English When powered-on, Token Ring interfaces operate in two different modes : `listen` and `transmit`. When operating in `listen` mode, a Token Ring interface receives an electrical signal from its upstream neighbor on the ring, introduces a delay equal to the transmission time of one bit on the ring and regenerates the signal before sending it to its downstream neighbor on the ring. 380/10000 · 380
125 ../../principles/transport.rst:747

	English The first scenario is when the remote entity receives an old `CR` segment. It considers this `CR` segment as a connection establishment attempt and replies by sending a `CA` segment. However, the initiating host cannot match the received `CA` segment with a previous connection attempt. It sends a control segment (`REJECT` in the figure below) to cancel the spurious connection attempt. The remote entity cancels the connection attempt upon reception of this control segment. 476/10000 · 476
125 ../../protocols/bgp.rst:440

	English From a theoretical perspective, these guidelines should be verified automatically to ensure that BGP will always converge in the global Internet. However, such a verification cannot be performed in practice because this would force all domains to disclose their routing policies (and few are willing to do so) and furthermore the problem is known to be NP-hard [GW1999]. 370/10000 · 370
125 ../../protocols/email.rst:252

	English b 1/10000 · 1
125 ../../protocols/ipv6.rst:407

	English 102 or 81 bytes 15/10000 · 15
125 ../../protocols/ethernet.rst:402

	English Virtual LANs 12/10000 · 12
125 ../../protocols/tcp.rst:357

	English These throughputs are acceptable in today's networks. However, there are already servers having 10 Gbps interfaces... Early TCP implementations had fixed receiving and sending buffers [#ftcphosts]_. Today's high performance implementations are able to automatically adjust the size of the sending and receiving buffer to better support high bandwidth flows [SMM1998]_. 368/10000 · 368
126 ../../bibliography.rst:325

	English Russell A., `Rough Consensus and Running Code and the Internet-OSI Standards War <https://dx.doi.org/10.1109/MAHC.2006.42>`_, IEEE Annals of the History of Computing, July-September 2006 186/10000 · 186

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