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../../glossary.rst:17
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a transmission mode where an information is sent from one source to `one` receiver that belongs to a specified group
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../../exercises/ex-sharing.rst:92
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Consider the following scenario for the ALOHA medium access control algorithm. Three hosts are attached to a one-kilometer long cable and transmit 1000 bits frames at 1 Mbps. Each arrow represents a request to transmit a frame on the corresponding host. Each square represents 250 microseconds in the figure. Represent all the transmitted frames and list the frames that collide.
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../../principles/transport.rst:25
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Networked applications do not exchange random messages. In order to ensure that the server is able to understand the queries sent by a client, and also that the client is able to understand the responses sent by the server, they must both agree on a set of syntactical and semantic rules. These rules define the format of the messages exchanged as well as their ordering. This set of rules is called an application-level `protocol`.
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../../principles/sharing.rst:28
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The second possible physical organization, which is also used inside computers to connect different extension cards, is the bus. In a bus network, all hosts are attached to a shared medium, usually a cable through a single interface. When one host sends an electrical signal on the bus, the signal is received by all hosts attached to the bus. A drawback of bus-based networks is that if the bus is physically cut, then the network is split into two isolated networks. For this reason, bus-based networks are sometimes considered to be difficult to operate and maintain, especially when the cable is long and there are many places where it can break. Such a bus-based topology was used in early Ethernet networks.
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../../principles/security.rst:64
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When analyzing security issues in computer networks, it is useful to reason about the capabilities of the attacker who wants to exploit some breach in the security of the network. There are different types of attackers. Some have generic capabilities, others are specific to a given technology or network protocol. In this section, we discuss some important threats that a network architect must take into account.
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../../exercises/dns.rst:33
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where
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../../exercises/email.rst:16
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Use your preferred email tool to send an email message to yourself containing a single line of text. Most email tools have the ability to show the `source` of the message, use this function to look at the message that you sent and the message that you received. Can you find an explanation for all the lines that have been added to your single line email ?
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../../exercises/http.rst:23
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Can you explain the different headers found in the response ?
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../../exercises/ipv6.rst:33 • ../../exercises/ipv6.rst:142
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Consider the network shown in the figure below. In this network, the following addresses are used.
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../../exercises/lan.rst:56
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Many enterprise networks are organized with a set of backbone devices interconnected by using a full mesh of links as shown in Fig.2. In this network, what are the benefits and drawbacks of using Ethernet switches and IP routers running OSPF ?
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../../exercises/routing-policies.rst:60
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from `AS4` to `AS1`
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../../exercises/routing-protocols.rst:94
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Finally, we can start the IPMininet_ topology and launch the daemons. The entire script is available from :download:`/exercises/ipmininet_scripts/ospf6.py`.
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../../exercises/tcp-2.rst:22
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packetdrill_ executes a system call and verifies its return value
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../../exercises/trace.rst:35
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A first solution to analyze this trace is to use tcpdump_ on the command line. The `-n` disables the reverse DNS lookups that tcpdump_ does by default for all IP addresses. The `-r` argument is the name of the file contained the captured packets. The trace starts with the DNS request. This request was sent over IPv4 which is the default on this host. tcpdump_ indicates the query and the response returned by the local DNS resolver.
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../../protocols/bgp.rst:27
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Interconnection of two domains via a private peering link
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../../protocols/congestion.rst:24
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`mild congestion`. TCP considers that the network is lightly congested if it receives three duplicate acknowledgments and performs a fast retransmit. If the fast retransmit is successful, this implies that only one segment has been lost. In this case, TCP performs multiplicative decrease and the congestion window is divided by `2`. The slow-start threshold is set to the new value of the congestion window.
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../../protocols/dnssec.rst:53
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The first field of the header is the `Identification` field. When Alice sends a DNS request, she places a 16-bits integer in this field and remembers it. When she receives a response, she uses this `Identification` field to locate the initial DNS request that she sent. The response is only used if its `Identification` matches a pending DNS request (containing the same question).
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../../protocols/email.rst:51
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client software, that allows users to easily create and read email messages
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../../protocols/ethernet.rst:56
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Impact of the frame length on the maximum channel utilisation [SH1980]_
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../../protocols/http.rst:18
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In the late 1980s, high energy physicists working at CERN_ had to efficiently exchange documents about their ongoing and planned experiments. `Tim Berners-Lee`_ evaluated several of the documents sharing techniques that were available at that time [B1989]_. As none of the existing solutions met CERN's requirements, they chose to develop a completely new document sharing system. This system was initially called the `mesh`. It was quickly renamed the `world wide web`. The starting point for the `world wide web` are hypertext documents. An hypertext document is a document that contains references (hyperlinks) to other documents that the reader can immediately access. Hypertext was not invented for the world wide web. The idea of hypertext documents was proposed in 1945 [Bush1945]_ and the first experiments were done during the 1960s [Nelson1965]_ [Myers1998]_ . Compared to the hypertext documents that were used in the late 1980s, the main innovation introduced by the `world wide web` was to allow hyperlinks to reference documents stored on different remote machines.
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