Exit Zen
46
../../bibliography.rst:311
English
Ramakrishnan, K.K. and Henry Yang, `The Ethernet Capture Effect: Analysis and Solution <http://www2.research.att.com/~kkrama/papers/capture_camera.pdf>`_, Proceedings of IEEE 19th Conference on Local Computer Networks, MN, Oct. 1994.
0/2330 · 233
46
../../glossary.rst:229
English
Frame-Relay
0/110 · 11
46
../../principles/reliability.rst:202
English
Framing
0/100 · 7
46
../../principles/security.rst:453
English
SHA-2 is another family of cryptographic hash functions designed by the NIST. Different variants of SHA-2 can produce has values of 224, 256, 384 or 512 bits.
0/1580 · 158
46
../../exercises/ipv6.rst:475
English
``p:0002::/64`` used on the link ``B1-R5``. ``B1`` uses address ``p:0002::B1/64``
0/810 · 81
46
../../exercises/routing-protocols.rst:542
English
We have configured the following addresses on the hosts.
0/560 · 56
46
../../exercises/tcp-2.rst:642
English
the round-trip-time is fixed and does not change during the lifetime of the TCP connection. We assume a fixed value of 100 milliseconds for the round-trip-time and a fixed value of 200 milliseconds for the retransmission timer.
0/2270 · 227
46
../../protocols/bgp.rst:137
English
`Withdraw message` to indicate a BGP `UPDATE` message containing one route that is withdrawn
0/920 · 92
46
../../protocols/congestion.rst:219
English
The TCP congestion control zoo
0/300 · 30
46
../../protocols/email.rst:220
English
The first computers used different techniques to represent characters in memory and on disk. During the 1960s, computers began to exchange information via tape or telephone lines. Unfortunately, each vendor had its own proprietary character set and exchanging data between computers from different vendors was often difficult. The 7 bits ASCII character table :rfc:`20` was adopted by several vendors and by many Internet protocols. However, ASCII became a problem with the internationalization of the Internet and the desire of more and more users to use character sets that support their own written language. A first attempt at solving this problem was the definition of the ISO-8859_ character sets by :term:`ISO`. This family of standards specified various character sets that allowed the representation of many European written languages by using 8 bits characters. Unfortunately, an 8-bits character set is not sufficient to support some widely used languages, such as those used in Asian countries. Fortunately, at the end of the 1980s, several computer scientists proposed to develop a standard that supports all written languages used on Earth today. The Unicode standard [Unicode]_ has now been adopted by most computer and software vendors. For example, Java always uses Unicode to manipulate characters, Python can handle both ASCII and Unicode characters. Internet applications are slowly moving towards complete support for the Unicode character sets, but moving from ASCII to Unicode is an important change that can have a huge impact on current deployed implementations. See, for example, the work to completely internationalize email :rfc:`4952` and domain names :rfc:`5890`.
0/16930 · 1693
46
../../protocols/ethernet.rst:180
English
40-100 Gbps
0/110 · 11
46
../../protocols/http.rst:170
English
the `User-Agent:` header provides information about the client that has generated the HTTP request. Some servers analyze this header line and return different headers and sometimes different documents for different user agents.
0/2270 · 227
46
../../protocols/ipv6.rst:162
English
the top half is divided in two smaller blocks, one for each small campus
0/720 · 72
46
../../protocols/ethernet.rst:172
English
Thin coaxial cable, 185m
0/240 · 24
46
../../protocols/routing.rst:145
English
all routers update their routing table
0/380 · 38
46
../../protocols/tcp.rst:143
English
In the original TCP specification :rfc:`793`, each TCP entity maintained a clock to compute the initial sequence number (:term:`ISN`) placed in the `SYN` and `SYN+ACK` segments. This made the ISN predictable and caused a security issue. The typical security problem was the following. Consider a server that trusts a host based on its IP address and allows the system administrator to log in from this host without giving a password [#frlogin]_. Consider now an attacker who knows this particular configuration and is able to send IP packets having the client's address as source. He can send fake TCP segments to the server, but does not receive the server's answers. If he can predict the `ISN` that is chosen by the server, he can send a fake `SYN` segment and shortly after the fake `ACK` segment confirming the reception of the `SYN+ACK` segment sent by the server. Once the TCP connection is open, he can use it to send any command to the server. To counter this attack, current TCP implementations add randomness to the `ISN`. One of the solutions, proposed in :rfc:`1948` is to compute the `ISN` as ::
0/11090 · 1109
46
../../protocols/tls.rst:215
English
the ``ServerHelloDone`` indicates that the server has sent all the messages for the first phase of the handshake.
0/1130 · 113
46
../../protocols/wifi.rst:126
English
IEEE 802.11 RTS frame format
0/280 · 28
47
../../bibliography.rst:312
English
Roberts, L., `ALOHA packet system with and without slots and capture <http://doi.acm.org/10.1145/1024916.1024920>`_. SIGCOMM Computer Communication Review 5, 2 (Apr. 1975), 28-42.
0/1790 · 179
47
../../principles/network.rst:187
English
By inspecting the source and destination addresses of packets, network nodes can automatically derive their forwarding tables. As we will discuss later, this technique is used in :term:`Ethernet` networks. Despite being widely used, it has two important drawbacks. First, packets sent to unknown destinations are broadcasted in the network even if the destination is not attached to the network. Consider the transmission of ten packets destined to `Z` in the network above. When a node receives a packet towards this destination, it can only broadcast that packet. Since `Z` is not attached to the network, no node will ever receive a packet whose source is `Z` to update its forwarding table. The second and more important problem is that few networks have a tree-shaped topology. It is interesting to analyze what happens when a port-address table is used in a network that contains a cycle. Consider the simple network shown below with a single host.
0/9540 · 954