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../../protocols/ethernet.rst:177
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Two pairs shielded twisted pair, 25m maximum
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../../protocols/http.rst:162
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:rfc:`1945` and :rfc:`2616` define headers that are specific to HTTP responses. These server headers include:
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../../protocols/ipv6.rst:155
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A `global routing prefix` that is assigned to the Internet Service Provider that owns this block of addresses
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../../protocols/ethernet.rst:169 • ../../protocols/wifi.rst:19
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Standard
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../../protocols/routing.rst:135
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To better represent LANs and reduce the number of OSPF packets that are exchanged, OSPF handles LAN differently. When OSPF routers boot on a LAN, they elect [#felection]_ one of them as the `Designated Router (DR)` :rfc:`2328`. The `DR` router `represents` the local area network, and advertises the LAN's subnet. Furthermore, LAN routers only exchange HELLO packets with the `DR`. Thanks to the utilization of a `DR`, the topology of the LAN appears as a set of point-to-point links connected to the `DR` router.
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../../protocols/rpc.rst:151
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Footnotes
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../../protocols/ssh.rst:305
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The exact algorithms used for the computation of these keys are defined in :rfc:`4253`
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../../protocols/tcp.rst:127
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the `acknowledgment number` set to the `sequence number` of the received `SYN+ACK` segment incremented by 1 :math:`\pmod{2^{32}}`
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../../protocols/tls.rst:175
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The ``Server Name Indication (SNI)`` extension defined in :rfc:`6066` is an important TLS extension for web servers. It is used by the client to indicate the name of the server that it wishes to contact. The IP address associated to this name has been queried from the DNS and used to establish the TCP connection. Why should the client indicate the server name in the TLS ``ClientHello`` ? The motivation is the same as for the ``Host`` header line in HTTP/1.0. With the SNI extension, a single TLS server can support several web sites that use different domain names. Thanks to the SNI extension, the server knows the concerned domain name at the start of the TLS session. Without this extension, hosting providers would have been forced use one IP address per TLS-enabled server.
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../../protocols/wifi.rst:105
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The astute reader may have noticed that the 802.11 data frames contain three 48-bits address fields [#f4addresses]_ . This is surprising compared to other protocols in the network and datalink layers whose headers only contain a source and a destination address. The need for a third address in the 802.11 header comes from the `infrastructure` networks. In such a network, frames are usually exchanged between routers and servers attached to the LAN and WiFi devices attached to one of the access points. The role of the three address fields is specified by bit flags in the `Frame Control` field.
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../../bibliography.rst:132
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Metcalfe R., Boggs, D., `Ethernet: Distributed packet-switching for local computer networks <http://doi.acm.org/10.1145/360248.3602530>`_. Communications of the ACM, 19(7):395--404, 1976.
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../../glossary.rst:319
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file transfer
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../../exercises/reliability.rst:91
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Same question as above, but assume now that both the sender and the receiver implement selective repeat. Note that the answer can be different from the above question.
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../../principles/network.rst:147
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The first technique assumes that the underlying network topology is a tree. A tree is the simplest network to be considered when forwarding packets. The main advantage of using a tree is that there is only one path between any pair of nodes inside the network. Since a tree does not contain any cycle, it is impossible to have forwarding loops in a tree-shaped network.
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../../principles/sharing.rst:182
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`Which packet(s) should be discarded ?` Once the network node has decided to discard packets, it needs to actually discard real packets.
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../../principles/security.rst:412
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In practice, encrypting a message to sign it can be computationally costly, in particular if the message is a large file. A faster solution would be to summarize the document and only sign the summary of the document. A naive approach could be based on a checksum or CRC computed over the message. Alice would then compute :math:`C=Checksum(M)` and :math:`SC=E_p(A_{priv},C)`. She would then send both `M` and `SC` to the recipient of the message who can easily compute `C` from `SC` and verify the authenticity of the message. Unfortunately, this solution does not protect Alice and the message's recipient against a man-in-the-middle attack. If Mallory can intercept the message sent by Alice, he can easily modify Alice's message and tweak it so that it has the same checksum as the original one. The CRCs, although more complex to compute, suffer from the same problem.
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../../exercises/ipv6.rst:436
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Sometimes, static routes must be configured on networks to enforce certain paths. Consider the six routers network shown in the figure below.
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../../exercises/routing-protocols.rst:512
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We can now run this simple network.
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../../exercises/tcp-2.rst:593
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Our last scenario is when the first segment sent is lost. In this case, two round-trip-times are required to retransmit the missing segment and recover from the loss. This script is available from :download:`/exercises/packetdrill_scripts/slow-start-frr3.pkt`.
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../../protocols/bgp.rst:131
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a list of IP prefixes that are withdrawn
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