Exit Zen
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../../glossary.rst:129
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CIDR
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../../exercises/ex-sharing.rst:561
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Assume now that `R1` is using round-robin scheduling instead of a FIFO buffer. One queue is used to store the packets sent by `A` and another for the packets sent by `B`. `A` sends one 1000 bits packet every second while `B` sends packets at 10 Mbps. What is the round-trip-time measured by each of these two hosts if each of the two queues of `R1` can store 5 packets ?
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../../exercises/reliability.rst:57
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the 16 bits or the 32 bits Cyclical Redundancy Checks (CRC) that are often used on disks, in zip archives and in datalink layer protocols. See http://rosettacode.org/wiki/CRC-32 for CRC-32 implementations in various languages.
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../../exercises/network.rst:240
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`R1->R5->R4` and `R3->R2->R4`
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../../exercises/sockets.rst:259
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Creating a new socket to communicate through a network
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../../principles/naming.rst:127
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if the server process moves to another physical server, all clients must be informed about the new server address
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../../principles/referencemodels.rst:116
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physical layer entities exchange bits
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../../principles/network.rst:104
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The figure illustrates some possible forwarding tables in this network. By inspecting the forwarding tables of the different routers, one can find the path followed by packets sent from a source to a particular destination. In the example above, host `A` sends its packet to router `R1`. `R1` consults its forwarding table and forwards the packet towards `R2`. Based on its own table, `R2` decides to forward the packet to `R5` that can deliver it to its destination. Thus, the path from `A` to `J` is `A -> R1 -> R2 -> R5 -> J`.
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../../principles/reliability.rst:66
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every millisecond, record the voltage applied on the electrical wire. If the voltage is set to ``+5V``, record the reception of bit `1`. Otherwise, record the reception of bit `0`
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../../principles/transport.rst:60
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Application-layer protocols exchange two types of messages. Some protocols such as those used to support electronic mail exchange messages expressed as strings or lines of characters. As the transport layer allows hosts to exchange bytes, they need to agree on a common representation of the characters. The first and simplest method to encode characters is to use the :term:`ASCII` table. :rfc:`20` provides the ASCII table that is used by many protocols on the Internet. For example, the table defines the following binary representations :
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../../principles/sharing.rst:139
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Congestion collapse on the Internet
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../../principles/security.rst:319
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DES, the Data Encryption Standard that became a standard in 1977 and has been widely used by industry. It uses 56 bits keys that are not considered sufficiently secure nowadays since attackers can launch brute-force attacks by testing all possible keys. Triple DES combines three 56 bits keys, making the brute force attacks more difficult.
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../../exercises/dns.rst:77
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sends DNS requests containing always the same identifier
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../../exercises/ipv6.rst:230
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router ``R4`` uses address ``2001:db8:1341:34::4`` on its West interface, address ``2001:db8:1341:24::4`` on its North interface, address ``2001:db8:1341:14::4`` on its North-West interface and address ``2001:db8:1341:4::4`` on its East interface
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../../exercises/lan.rst:310
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Thanks to the traces collected by tcpdump_, we can easily analyze the messages exchanged by the switches. Here is the fist message sent by switch ``s3``.
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../../exercises/routing-protocols.rst:357
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We can observe the RIPng messages that are exchanged over the network. :rfc:`2080` defines two types of RIPng messages:
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../../exercises/tcp-2.rst:145
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Another interesting features of packetdrill_ is that it is possible to inspect the state maintained by the Linux kernel for the underlying connection using the ``TCP_INFO`` socket option. This makes it possible to retrieve the value of some variables of the TCP control block.
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../../protocols/bgp.rst:84
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A domain's import and export filters can be defined by using the Route Policy Specification Language (RPSL) specified in :rfc:`2622` [GAVE1999]_ . Some Internet Service Providers, notably in Europe, use RPSL to document [#fripedb]_ their import and export policies. Several tools help to easily convert a RPSL policy into router commands.
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../../protocols/congestion.rst:146
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To solve this problem, :rfc:`3168` uses an additional bit in the TCP header : the `Congestion Window Reduced` (CWR) bit.
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../../protocols/dnssec.rst:288
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Given the above security risks, DNSSEC opted for a different approach that allows the negative replies to be authenticated by using offline signatures. The `NSEC` record exploits the lexicographical ordering of all the domain names. To understand its usage, consider a simple domain that contains three names (the associated `AAAA` and other records that are not shown) :
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