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../../protocols/tcp.rst:623
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Several researchers have analyzed the utilization of TCP and UDP in the global Internet. Most of these studies have been performed by collecting all the packets transmitted over a given link during a period of a few hours or days and then analyzing their headers to infer the transport protocol used, the type of application, ... Recent studies include http://www.caida.org/research/traffic-analysis/tcpudpratio/, https://research.sprintlabs.com/packstat/packetoverview.php or http://www.nanog.org/meetings/nanog43/presentations/Labovitz_internetstats_N43.pdf
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../../glossary.rst:206
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The telnet protocol is defined in :rfc:`854`
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../../principles/linkstate.rst:73
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To deal with the memory corruption problem, link state packets contain a checksum or CRC. This checksum is computed by the router that generates the LSP. Each router must verify the checksum when it receives or floods an LSP. Furthermore, each router must periodically verify the checksums of the LSPs stored in its LSDB. This enables them to cope with memory errors that could corrupt the LSDB as the one that occurred in the ARPANET.
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../../principles/reliability.rst:768
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the `go-back-n` receiver does not accept out-of-sequence frames
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../../principles/sharing.rst:1041
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A congestion control scheme for our simple transport protocol could be implemented as follows.
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../../protocols/email.rst:305
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00010100 11111011
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../../protocols/ipv6.rst:645
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The broadcast service allows easily reaching all devices attached to a datalink layer network. It has been widely used to support IP version 4. A drawback of using the broadcast service to support a network layer protocol is that a broadcast frame that contains a network layer packet is always delivered to all devices attached to the datalink network, even if some of these devices do not support the network layer protocol. The multicast service is a useful alternative to the broadcast service. To understand its operation, it is important to understand how a datalink layer interface operates. In shared media LANs, all devices are attached to the same physical medium and all frames are delivered to all devices. When such a frame is received by a datalink layer interface, it compares the destination address with the MAC address of the device. If the two addresses match, or the destination address is the broadcast address, the frame is destined to the device and its payload is delivered to the network layer protocol. The multicast service exploits this principle. A multicast address is a logical address. To receive frames destined to a multicast address in a shared media LAN, a device captures all frames having this multicast address as their destination. All IPv6 nodes are capable of capturing datalink layer frames destined to different multicast addresses.
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../../protocols/wifi.rst:160
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In fact, the [IEEE802.11]_ frame format contains a fourth optional address field. This fourth address is only used when an 802.11 wireless network is used to interconnect bridges attached to two classical LAN networks.
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../../protocols/tcp.rst:625
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This 32 bits counter was specified in :rfc:`793`. A 32 bits counter that is incremented every 4 microseconds wraps in about 4.5 hours. This period is much larger than the Maximum Segment Lifetime that is fixed at 2 minutes in the Internet (:rfc:`791`, :rfc:`1122`).
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../../glossary.rst:238
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TLD
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../../principles/linkstate.rst:75
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Flooding is illustrated in the figure below. By exchanging HELLO messages, each router learns its direct neighbors. For example, router `E` learns that it is directly connected to routers `D`, `B` and `C`. Its first LSP has sequence number `0` and contains the directed links `E->D`, `E->B` and `E->C`. Router `E` sends its LSP on all its links and routers `D`, `B` and `C` insert the LSP in their LSDB and forward it over their other links.
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../../principles/reliability.rst:769
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the `go-back-n` sender retransmits all unacknowledged frames once it has detected a loss
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../../principles/sharing.rst:1060
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In the above pseudocode, `cwin` contains the congestion window stored as a real number of segments. This congestion window is updated upon the arrival of each acknowledgment and when congestion is detected. For simplicity, we assume that `cwin` is stored as a floating point number but only full segments can be transmitted.
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../../protocols/email.rst:307
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000101 001111 101100
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../../protocols/ipv6.rst:649
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Interactions between IPv6 and the datalink layer
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../../protocols/tcp.rst:627
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On many departmental networks containing Unix workstations, it was common to allow users on one of the hosts to use ``rlogin`` :rfc:`1258` to run commands on any of the workstations of the network without giving any password. In this case, the remote workstation "authenticated" the client host based on its IP address. This was a bad practice from a security viewpoint.
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../../glossary.rst:240
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A Top-level domain name. There are two types of TLDs. The ccTLD are the TLD that correspond to a two letters :term:`ISO-3166` country code. The gTLD are the generic TLDs that are not assigned to a country.
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../../principles/reliability.rst:776
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`Selective repeat` is a better strategy to recover from losses. Intuitively, `selective repeat` allows the receiver to accept out-of-sequence frames. Furthermore, when a `selective repeat` sender detects losses, it only retransmits the frames that have been lost and not the frames that have already been correctly received.
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../../principles/sharing.rst:1063
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As an illustration, let us consider the network scenario above and assume that the router implements the DECBit binary feedback scheme [RJ1995]_. This scheme uses a form of Forward Explicit Congestion Notification and a router marks the congestion bit in arriving packets when its buffer contains one or more packets. In the figure below, we use a `*` to indicate a marked packet.
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../../protocols/email.rst:309
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5 15 44
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