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../../protocols/ipv6.rst:111
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It is sometimes necessary to write IPv6 addresses in text format, e.g. when manually configuring addresses or for documentation purposes. The preferred format for writing IPv6 addresses is ``x:x:x:x:x:x:x:x``, where the ``x`` 's are hexadecimal digits representing the eight 16-bit parts of the address. Here are a few examples of IPv6 addresses :
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../../protocols/ethernet.rst:72
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The transport and datalink layers usually chose different strategies to place their CRCs or checksums. Transport layer protocols usually place their CRCs or checksums in the segment header. Datalink layer protocols sometimes place their CRC in the frame header, but often in a trailer at the end of the frame. This choice reflects implementation assumptions, but also influences performance :rfc:`893`. When the CRC is placed in the trailer, as in Ethernet, the datalink layer can compute it while transmitting the frame and insert it at the end of the transmission. All Ethernet interfaces use this optimization today. When the checksum is placed in the header, as in a TCP segment, it is impossible for the network interface to compute it while transmitting the segment. Some network interfaces provide hardware assistance to compute the TCP checksum, but this is more complex than if the TCP checksum were placed in the trailer [#ftso]_.
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../../protocols/routing.rst:84
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OSPF areas
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../../protocols/rpc.rst:104
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`params`: a structure that contains the values of the parameters that are passed to the method
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../../protocols/ssh.rst:211
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It is common practice among designers of security protocols to never use the same key for different purposes. For example, allowing the client and the server to use the same key to encrypt data could enable an attacker to launch a replay attack by sending to the client data that it has itself encrypted.
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../../protocols/tcp.rst:53
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the `PSH` flag is used as a notification from the sender to indicate to the receiver that it should pass all the data it has received to the receiving process. However, in practice TCP implementations do not allow TCP users to indicate when the `PSH` flag should be set.
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../../protocols/tls.rst:84
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A TLS session is divided in two phases: the handshake and the data transfer. During the handshake, the client and the server negotiate the security parameters and the keys that will be used to secure the data transfer. During the second phase, all the messages exchanged are encrypted and authenticated with the negotiated algorithms and keys.
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../../protocols/udp.rst:90
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This limitation is due to the fact that the network layer cannot transport packets that are larger than 64 KBytes. As UDP does not include any segmentation/reassembly mechanism, it cannot split a SDU before sending it. The UDP header consumes 8 bytes and the IPv6 header 60. With IPv4, the IPv4 header only consumes 20 bytes and thus the maximum UDP payload size is 65507 bytes.
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../../protocols/wifi.rst:25
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19 Mbps
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../../bibliography.rst:93
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ISO, `Intermediate System to Intermediate System intra-domain routeing information exchange protocol for use in conjunction with the protocol for providing the connectionless-mode network service (ISO 8473) <http://standards.iso.org/ittf/PubliclyAvailableStandards/c030932_ISO_IEC_10589_2002(E).zip>`_ , 2002
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../../glossary.rst:131
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Classless Inter Domain Routing is the current address allocation architecture for IP version 4. It was defined in :rfc:`1518` and :rfc:`4632`.
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../../exercises/ex-sharing.rst:564
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When analyzing the reaction of a network using round-robin schedulers, it is sometimes useful to consider that the packets sent by each source are equivalent to a fluid and that each scheduler acts as a tap. Using this analogy, consider the network below. In this network, all the links are 100 Mbps and host `B` is sending packets at 100 Mbps. If A sends at 1, 5, 10, 20, 30, 40, 50, 60, 80 and 100 Mbps, what is the throughput that destination `D` will receive from `A`. Use this data to plot a graph that shows the portion of the traffic sent by host `A` which is received by host `D`.
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../../principles/transport.rst:62
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`A` : `1000011b`
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../../principles/sharing.rst:141
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Congestion collapse is unfortunately not only an academic experience. Van Jacobson reports in [Jacobson1988]_ one of these events that affected him while he was working at the Lawrence Berkeley Laboratory (LBL). LBL was two network nodes away from the University of California in Berkeley. At that time, the link between the two sites had a bandwidth of 32 Kbps, but some hosts were already attached to 10 Mbps LANs. "In October 1986, the data throughput from LBL to UC Berkeley ... dropped from 32 Kbps to 40 bps. We were fascinated by this sudden factor-of-thousand drop in bandwidth and embarked on an investigation of why things had gotten so bad." This work lead to the development of various congestion control techniques that have allowed the Internet to continue to grow without experiencing widespread congestion collapse events.
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../../principles/security.rst:324
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RC4 is an encryption scheme defined in the late 1980s by Ron Rivest for RSA Security. Given the speed of its software implementation, it has been included in various protocols and implementations. However, cryptographers have identified several weaknesses in this algorithm. It is now deprecated and should not be used anymore :rfc:`7465`.
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../../exercises/dns.rst:78
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sends DNS requests containing identifiers that are incremented by one after each request
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../../exercises/ipv6.rst:232
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Can you configure the forwarding tables so that the following paths are used by packets sent by host ``A`` to reach one of the four addresses of router ``R4``?
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../../exercises/routing-protocols.rst:359
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the requests
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../../exercises/tcp-2.rst:147
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Let us first explore how a TCP connection can be established. In the previous script, we have injected the segments that a client would send to a server. We can also use the Linux stack as a client and inject the segments that a server would return. Such a client process would first create its :manpage:`socket`` and then issue the :manpage:`connect` system call. At this point, the stack sends a ``SYN`` segment. To simplify the scripts, we have configured the stack to use a ``MSS`` of 1000 bytes and disabled the TCP extensions (the details of this configuration may be found at the beginning of the script). The server replies with a ``SYN+ACK`` and the stack sends acknowledges it to finish the three-way-handshake.
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../../protocols/bgp.rst:86
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The figure below provides a simple example of import and export filters for two domains in a simple internetwork. In RPSL, the keyword `ANY` is used to replace any route from any domain. It is typically used by a provider to indicate that it announces all its routes to a customer over a `provider->customer` relationship. This is the case for `AS4`'s export policy. The example below clearly shows the difference between a `provider->customer` and a `shared-cost` peering relationship. `AS4`'s export filter indicates that it announces only its internal routes (`AS4`) and the routes learned from its clients (`AS7`) over its `shared-cost` peering with `AS3`, while it advertises all the routes that it uses (including the routes learned from `AS3`) to `AS7`.
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