Exit Zen
33
../../protocols/wifi.rst:35
English
The architecture of WiFi networks is slightly different from the Local Area Networks that we have discussed until now. There are, in practice, two main types of WiFi networks : `independent` or `adhoc` networks and `infrastructure` networks [#fBSS]_. An `independent` or `adhoc` network is composed of a set of devices that communicate with each other. These devices play the same role and the `adhoc` network is usually not connected to the global Internet. `Adhoc` networks are used when for example a few laptops need to exchange information or to connect a computer with a WiFi printer.
0/5910 · 591
34
../../bibliography.rst:107
English
Kleinrock, L., Tobagi, F., `Packet Switching in Radio Channels: Part I--Carrier Sense Multiple-Access Modes and their Throughput-Delay Characteristics <https://dx.doi.org/10.1109/TCOM.1975.1092768>`_, IEEE Transactions on Communications, Vol. COM-23, No. 12, pp. 1400-1416, December 1975.
0/2880 · 288
34
../../glossary.rst:171
English
eBGP
0/100 · 4
34
../../exercises/ex-sharing.rst:630
English
Hosts `A` and `B` use the simple congestion control scheme described in the book and router `R1` uses the DECBIT mechanism to mark packets as soon as its buffers contain one packet. Hosts `A` and `B` need to send five segments and start exactly at the same time. How long does each hosts needs to wait to receive the acknowledgment for its fifth segment ?
0/3550 · 355
34
../../principles/network.rst:130
English
The simplest `control plane` for a network is to manually compute the forwarding tables of all routers inside the network. This simple control plane is sufficient when the network is (very) small, usually up to a few routers.
0/2250 · 225
34
../../principles/transport.rst:71
English
`line feed` (`LF`) : `0001010b`
0/310 · 31
34
../../principles/sharing.rst:155
English
When a network node forwards small packets, its performance is usually limited by the number of lookup operations that it can perform every second. This lookup performance is measured in packets per second. The performance may depend on the length of the forwarded packets. The key performance factor is the number of minimal size packets that are forwarded by the node every second. This rate can lead to a capacity in bits per second which is much lower than the sum of the bandwidth of the node's links.
0/5060 · 506
34
../../principles/security.rst:375
English
A public key cryptographic scheme is a combination of two functions :
0/690 · 69
34
../../exercises/dns.rst:113
English
On a Linux machine, the *Description* section of the `dig` man page tells you where `dig` finds the list of nameservers to query.
0/1290 · 129
34
../../exercises/ipv6.rst:330
English
The students have configured the following forwarding tables on these six routers.
0/820 · 82
34
../../exercises/routing-protocols.rst:380
English
To explore the configuration of BGP, let us consider a network that contains three ASes: ``AS1``, ``AS2`` and ``AS3``. To simplify the tests, we identify one host inside each of these ASes.
0/1900 · 190
34
../../exercises/tcp-2.rst:261
English
Let us first use packetdrill_ to explore the evolution of the TCP retransmission timeout. The value of this timeout is set based on the measured round-trip-time and its variance. When the retransmission timer expires, TCP doubles the retransmission timer. This exponential backoff mechanism is important to ensure that TCP slowdowns during very severe congestion periods. We use the ``tcpi_rto`` variable from ``TCP_INFO`` to track the evolution of the retransmission timer. This script is available from :download:`/exercises/packetdrill_scripts/rto.pkt`.
0/5560 · 556
34
../../protocols/bgp.rst:116
English
A BGP peering session between two directly connected routers
0/600 · 60
34
../../protocols/congestion.rst:189
English
Thanks to its congestion control scheme, TCP adapts its transmission rate to the losses that occur in the network. Intuitively, the TCP transmission rate decreases when the percentage of losses increases. Researchers have proposed detailed models that allow the prediction of the throughput of a TCP connection when losses occur [MSMO1997]_ . To have some intuition about the factors that affect the performance of TCP, let us consider a very simple model. Its assumptions are not completely realistic, but it gives us good intuition without requiring complex mathematics.
0/5720 · 572
34
../../protocols/email.rst:178
English
Inside the email header, the `Content-Type:` header line indicates how the MIME email message is structured. :rfc:`2046` defines the utilization of this header line. The two most common structures for MIME messages are :
0/2200 · 220
34
../../protocols/ethernet.rst:174
English
10Base-F
0/100 · 8
34
../../protocols/http.rst:146
English
the `GET` method is the most popular one. It is used to retrieve a document from a server. The `GET` method is encoded as `GET` followed by the path of the URI of the requested document and the version of HTTP used by the client. For example, to retrieve the http://www.w3.org/MarkUp/ URI, a client must open a TCP connection on port `80` with host `www.w3.org` and send a HTTP request containing the following line:
0/4160 · 416
34
../../protocols/http2.rst:234
English
HTTP/2.0 includes much more than what we have covered in this short introduction. There is for example a `Ping` frame that allows measuring the round-trip-time between a client and a server or the `GoAway` frame that indicates the termination of an HTTP/2.0 session. This frame contains an error code that indicates why the session has been terminated. Several error codes are defined in :rfc:`7540`, including `ENHANCE_YOUR_CALM` that is used to indicate that the other endpoint exhibits an behavior that could cause excessive load.
0/5330 · 533
34
../../protocols/ipv6.rst:122
English
``0:0:0:0:0:0:0:0`` is represented as ``::``
0/440 · 44
34
../../protocols/ethernet.rst:109
English
Several physical layers have been defined for Ethernet networks. The first physical layer, usually called 10Base5, provided 10 Mbps over a thick coaxial cable. The characteristics of the cable and the transceivers that were used then enabled the utilization of 500 meter long segments. A 10Base5 network can also include repeaters between segments.
0/3480 · 348