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../../principles/transport.rst:148
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An `unreliable connectionless` service may suffer from various types of problems compared to a `reliable connectionless service`. First of all, an `unreliable connectionless service` does not guarantee the delivery of all SDUs. This can be expressed graphically by using the time-sequence diagram below.
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../../principles/sharing.rst:231
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Distributing the load across the network
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../../principles/security.rst:559
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Unfortunately, this solution forces Bob to store Alice's password in clear. Any breach in the security of Bob's computer would reveal Alice's password. Such breaches unfortunately occur and some of them have led to the dissemination of millions of passwords.
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../../exercises/ipv6.rst:517
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Assign IP subnets to all links in this network so that you can reduce the number of entries in the forwarding tables of all routers. Assume that you have received a ``/56`` prefix that you can use as you want. Each subnet containing a host must be allocated a ``/64`` subnet.
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../../exercises/routing-protocols.rst:685
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This router (`as1`) has two BGP neighbors: ``2001:cafe:1:12::2`` and ``2001:cafe:1:13::3``. Both BGP sessions are established using the current version of the protocol (version 4). About 50 messages were sent/received over each session. These messages are mainly the BGP Keepalive messages that are exchanged every 30 seconds. The last column indicates that two prefixes were received over each session. We can see more details about these two eBGP sessions with the `show bgp neighbors` command.
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../../exercises/tcp-2.rst:686
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Can you explain why the congestion window is increased after the reception of the first acknowledgment ?
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../../protocols/bgp.rst:164
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the `Adj-RIB-Out` contains the BGP routes that have been advertised to each BGP peer. The `Adj-RIB-Out` for a given peer is built by applying the peer's `export filter` on the routes that have been installed in the `FIB`. There is one `export filter` per BGP peer. For this reason, the Adj-RIB-Out of a peer may contain different routes than the Adj-RIB-Out of another peer.
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../../protocols/congestion.rst:236
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In this pseudo-code, we assume that TCP uses unlimited sequence and acknowledgment numbers. Furthermore, we do not detail how the `cwnd` is adjusted after the retransmission of the lost segment by fast retransmit. Additional details may be found in :rfc:`5681`.
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../../protocols/email.rst:232
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R
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../../protocols/ethernet.rst:203
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Fortunately, IEEE was able to define the [IEEE802.3]_ frame format while maintaining backward compatibility with the Ethernet [DIX]_ frame format. The trick was to only assign values above 1500 as `EtherType` values. When a host receives a frame, it can determine whether the frame's format by checking its `EtherType/Length` field. A value lower smaller than `1501` is clearly a length indicator and thus an [IEEE802.3]_ frame. A value larger than `1501` can only be type and thus a [DIX]_ frame.
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../../protocols/http.rst:187
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All status codes starting with digit `2` indicate a valid response. `200 Ok` indicates that the HTTP request was successfully processed by the server and that the response is valid.
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../../protocols/ipv6.rst:180
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``/56`` for small user sites
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../../protocols/ethernet.rst:176
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Two multi-mode optical fiber, 2 km maximum
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../../protocols/routing.rst:169
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Footnotes
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../../protocols/tcp.rst:None
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Denial of Service attacks
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../../protocols/tls.rst:283
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The client sends the ``ChangeCipherSpec`` message followed by the ``Finished`` message. The ``ChangeCipherSpec`` message indicates that the client has received all the information required to generate the security keys for this TLS session. This messages can also appear later in the session to indicate a change in the encryption algorithms that are used, but this usage is outside the scope of this book. The ``Finished`` message is more important. It confirms to the server that the TLS handshake has been performed correctly and that no attacker has been able to modify the data sent by the client or the server. This is the first message that is encrypted with the selected security keys. It contains a hash of all the messages that were exchanged during the handshake.
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../../protocols/wifi.rst:154
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The second important utilization of the management frames is to allow a WiFi station to be associated with an access point. When a WiFi station starts, it listens to beacon frames to find the available SSIDs. To be allowed to send and receive frames via an access point, a WiFi station must be associated to this access point. If the access point does not use any security mechanism to secure the wireless transmission, the WiFi station simply sends an `Association request` frame to its preferred access point (usually the access point that it receives with the strongest radio signal). This frame contains some parameters chosen by the WiFi station and the SSID that it requests to join. The access point replies with an `Association response frame` if it accepts the WiFI station.
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../../bibliography.rst:330
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Sklower, K. 1989. `Improving the efficiency of the OSI checksum calculation <http://doi.acm.org/10.1145/74681.74684>`_. SIGCOMM Computer Communication Review 19, 5 (Oct. 1989), 32-43.
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../../glossary.rst:264
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The HyperText Markup Language specifies the structure and the syntax of the documents that are exchanged on the world wide web. HTML is maintained by the `HTML working group <https://www.w3.org/html/wg/>`_ of the :term:`W3C`
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../../principles/network.rst:249
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For example, consider again the network topology above. `A` sends a control packet towards `B`. The initial `record route` is empty. When `R1` receives the packet, it adds its own address to the `record route` and forwards a copy to `R2` and another to `R3`. `R2` receives the packet, adds itself to the `record route` and forwards it to `R3`. `R3` receives two copies of the packet. The first contains the `[R1,R2]` `record route` and the second `[R1]`. In the end, `B` will receive two control packets containing `[R1,R2,R3,R4]` and `[R1,R3,R4]` as `record routes`. `B` can keep these two paths or select the best one and discard the second. A popular heuristic is to select the `record route` of the first received packet as being the best one since this likely corresponds to the shortest delay path.
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