Exit Zen
3
../../principles/sharing.rst:16
English
A network is designed to support a potentially large number of users that exchange information with each other. These users produce and consume information which is exchanged through the network. To support its users, a network uses several types of resources. It is important to keep in mind the different resources that are shared inside the network.
0/3520 · 352
4
../../bibliography.rst:13
English
LAN/MAN Standards Committee of the IEEE Computer Society. IEEE Standard for Information Technology - Telecommunications and information exchange between systems - local and metropolitan area networks - specific requirements - Part 3 : Carrier Sense multiple access with collision detection (CSMA/CD) access method and physical layer specification. IEEE, 2000. Available from http://standards.ieee.org/getieee802/802.3.html
0/4220 · 422
4
../../glossary.rst:183
English
AIMD
0/100 · 4
4
../../exercises/ex-sharing.rst:17
English
To understand the operation of Medium Access Control algorithms, it is often interesting to use a geometric representation of the transmission of frames on a shared medium. This representation is suitable if the communicating devices are attached to a single cable. Consider a simple scenario with a host connected at one end of a cable. For simplicity, let us consider a cable that has a length of one kilometer. Let us also consider that the propagation delay of the electrical signal is five microseconds per kilometer. The figure below shows the transmission of a 2000 bits frame at 100 Mbps by host A on the cable.
0/6190 · 619
4
../../exercises/intro.rst:12
English
A good understanding of the topics covered by this e-book can only be obtained by solving the proposed exercises. Reading the e-book from the first to the last page is not sufficient to get a detailed knowledge of computer networking.
0/2340 · 234
4
../../exercises/network.rst:16
English
The network below uses port forwarding with flat addresses. The network boots and all hosts start one after the other. Explain at each step how the packets are forwarded and how the port forwarding tables of the network nodes are modified. Host `C` sends a packet to host `B`. Some time later, host `A` sends a packet to host `C`. Finally, host `B` sends a packet to host `A`.
0/3760 · 376
4
../../exercises/reliability.rst:16
English
Transmission links have sometimes different upstream and downstream bandwidths. A typical example are access networks that use ADSL (Asymmetric Digital Subscriber Lines). Consider two hosts connected via an ADSL link having an upstream bandwidth of 1 Mbps and a downstream bandwidth of 50 Mbps. The propagation delay between the two hosts is 10 milliseconds. What is the maximum throughput, expressed in frames/second, that the alternating bit protocol can obtain on this link if each data frame has a length of 125 bytes and acknowledgments are 25 bytes long. Same question if the protocol is modified to support 1500 bytes long data frames.
0/6420 · 642
4
../../exercises/sockets.rst:98
English
Networked applications were usually implemented by using the :term:`socket` :term:`API`. This API was designed when TCP/IP was first implemented in the `Unix BSD`_ operating system [Sechrest]_ [LFJLMT]_, and has served as the model for many APIs between applications and the networking stack in an operating system. Although the socket API is very popular, other APIs have also been developed. For example, the STREAMS API has been added to several Unix System V variants [Rago1993]_. The socket API is supported by most programming languages and several textbooks have been devoted to it. Users of the C language can consult [DC2009]_, [Stevens1998]_, [SFR2004]_ or [Kerrisk2010]_. The Java implementation of the socket API is described in [CD2008]_ and in the `Java tutorial <http://java.sun.com/docs/books/tutorial/networking/sockets/index.html>`_. In this section, we will use the C socket API to illustrate the key concepts.
0/9290 · 929
4
../../principles/network.rst:15
English
The main objective of the network layer is to allow hosts, connected to different networks, to exchange information through intermediate systems called :term:`router`. The unit of information in the network layer is called a :term:`packet`.
0/2400 · 240
4
../../principles/referencemodels.rst:19
English
The five layers reference model
0/310 · 31
4
../../principles/reliability.rst:31
English
To enable the two hosts to exchange information, they need to be linked together by some kind of physical media. Computer networks have used various types of physical media to exchange information, notably :
0/2070 · 207
5
../../bibliography.rst:14
English
LAN/MAN Standards Committee of the IEEE Computer Society. IEEE Standard for Information technology--Telecommunications and information exchange between systems--Local and metropolitan area networks--Specific requirements--Part 5: Token Ring Access Method and Physical Layer Specification. IEEE, 1998. available from http://standards.ieee.org/getieee802
0/3520 · 352
5
../../glossary.rst:185
English
Additive Increase, Multiplicative Decrease. A rate adaption algorithm used notably by TCP where a host additively increases its transmission rate when the network is not congested and multiplicatively decreases when congested is detected.
0/2380 · 238
5
../../exercises/ex-sharing.rst:42
English
If the transmitting host is located at another position on the shared medium than one of the edges, then the geometrical pattern that represents the transmission of a frame is slightly different. If the transmitting host is placed in the middle of the cable, then the signal is transmitted in both directions on the cable. The figure below shows the transmission of one 100 bits frame at 100 Mbps by host C on the same cable.
0/4250 · 425
5
../../exercises/network.rst:42
English
Same question as above, but the network is modified as shown in the figure below.
0/810 · 81
5
../../exercises/reliability.rst:19
English
How would you set the duration of the retransmission timer in the alternating bit protocol ?
0/920 · 92
5
../../exercises/sockets.rst:100
English
The socket API is quite low-level and should be used only when you need a complete control of the network access. If your application simply needs, for instance, to retrieve data from a web server, there are much simpler and higher-level APIs.
0/2430 · 243
5
../../exercises/transport.rst:18
English
A reliable connection oriented transport places a 32 bits sequence number inside the segment header to number the segments. This sequence number is incremented for each data segment. The connection starts as shown in the figure below :
0/2350 · 235
5
../../principles/naming.rst:15
English
Because names are at a higher level than addresses, they allow (both in the example of programming above, and on the Internet) to treat addresses as mere technical identifiers, which can change at will. Only the names are stable.
0/2290 · 229
5
../../principles/network.rst:18
English
Before explaining the operation of the network layer, it is useful to remember the characteristics of the service provided by the `datalink` layer. There are many variants of the datalink layer. Some provide a reliable service while others do not provide any guarantee of delivery. The reliable datalink layer services are popular in environments such as wireless networks where transmission errors are frequent. On the other hand, unreliable services are usually used when the physical layer provides an almost reliable service (i.e. only a negligible fraction of the frames are affected by transmission errors). Such `almost reliable` services are frequently used in wired and optical networks. In this chapter, we will assume that the datalink layer service provides an `almost reliable` service since this is both the most general one and also the most widely deployed one.
0/8770 · 877