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71 ../../exercises/routing-protocols.rst:991
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — We can use IPMininet_ to prepare some networks with problems that need to be analyzed and corrected. 100/10000 · 100
71 ../../protocols/bgp.rst:289
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — If the link between `R2` and `R3` fails, `R3` detects the failure as it did not receive `KEEPALIVE` messages recently from `R2`. At this time, `R3` removes from its RIB all the routes learned over the `R2-R3` BGP session. `R2` also removes from its RIB the routes learned from `R3`. `R2` also sends `W(2001:db8:acbd::/48)` to `R1` over the `R1-R3` BGP session since it does not have a route anymore towards this prefix. 420/10000 · 420
71 ../../protocols/email.rst:236
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — k 1/10000 · 1
71 ../../protocols/ethernet.rst:327
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — In this network, the STP will compute the following spanning tree. `Switch1` will be the root of the tree. All the interfaces of `Switch1`, `Switch2` and `Switch7` are part of the spanning tree. Only the interface connected to `LAN B` will be active on `Switch9`. `LAN H` will only be served by `Switch7` and the port of `Switch44` on `LAN G` will be disabled. A frame originating on `LAN B` and destined for `LAN A` will be forwarded by `Switch7` on `LAN C`, then by `Switch1` on `LAN E`, then by `Switch44` on `LAN F` and eventually by `Switch2` on `LAN A`. 559/10000 · 559
71 ../../protocols/http.rst:362
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Then the client requested the web server's icon [#ffavicon]_. This server does not contain such an icon and thus replies with a `404` HTTP status. However, the underlying TCP connection is not closed immediately. 212/10000 · 212
71 ../../protocols/ipv6.rst:241
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The last type of unicast IPv6 addresses are the `Link Local Unicast` addresses. These addresses are part of the `fe80::/10` address block and are defined in :rfc:`4291`. Each host can compute its own link local address by concatenating the `fe80::/64` prefix with the 64 bits identifier of its interface. Link local addresses can be used when hosts that are attached to the same link (or local area network) need to exchange packets. They are used notably for address discovery and auto-configuration purposes. Their usage is restricted to each link and a router cannot forward a packet whose source or destination address is a link local address. Link local addresses have also been defined for IPv4 :rfc:`3927`. However, the IPv4 link local addresses are only used when a host cannot obtain a regular IPv4 address, e.g. on an isolated LAN. 841/10000 · 841
71 ../../protocols/ethernet.rst:248
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — An `Ethernet switch` understands the format of the Ethernet frames and can selectively forward frames over each interface. For this, each `Ethernet switch` maintains a `MAC address table`. This table contains, for each MAC address known by the switch, the identifier of the switch's port over which a frame sent towards this address must be forwarded to reach its destination. This is illustrated below with the `MAC address table` of the bottom switch. When the switch receives a frame destined to address `B`, it forwards the frame on its South port. If it receives a frame destined to address `D`, it forwards it only on its North port. 639/10000 · 639
71 ../../protocols/tcp.rst:231
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — :rfc:`793` also defines two special options that must be supported by all TCP implementations. The first option is `End of option`. It is encoded as a single byte having value `0x00` and can be used to ensure that the TCP header extension ends on a 32 bits boundary. The `No-Operation` option, encoded as a single byte having value `0x01`, can be used when the TCP header extension contains several TCP options that should be aligned on 32 bit boundaries. All other options [#ftcpoptions]_ are encoded using the TLV format. 523/10000 · 523
71 ../../protocols/tls.rst:383
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — In 2013, the statistics collected by the Firefox Telemetry project [#ftelemetry]_ revealed that 30% of the web pages loaded by Firefox users were done over HTTPS. In October 2019, 80% of the web pages are loaded over HTTPS. In six years, HTTPS became the dominant protocol to access web services. Another look at the deployment of HTTPS on web sites may be found in [Helme2019]_. 379/10000 · 379
71 ../../principles/network.rst:418
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Router `R1` fragments the packet into two fragments before transmitting them to router `R2`. Router `R2` reassembles the two packet fragments in a larger packet before transmitting them on the link towards host `B`. 215/10000 · 215
71 ../../bibliography.rst:93
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Helme, S., `Top 1 Million Analysis - September 2019 <https://scotthelme.co.uk/top-1-million-analysis-september-2019/>`_, 2019, https://scotthelme.co.uk/top-1-million-analysis-september-2019/ 190/10000 · 190
71 ../../principles/sharing.rst:454
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The first version of ALOHANet, described in [Abramson1970]_, operated as follows. First, the terminals and the mainframe exchanged fixed-length frames composed of 704 bits. Each frame contained 80 8-bit characters, some control bits and parity information to detect transmission errors. Two channels in the 400 MHz range were reserved for the operation of ALOHANet. The first channel was used by the mainframe to send frames to all terminals. The second channel was shared among all terminals to send frames to the mainframe. As all terminals share the same transmission channel, there is a risk of collision. To deal with this problem as well as transmission errors, the mainframe verified the parity bits of the received frame and sent an acknowledgment on its channel for each correctly received frame. The terminals on the other hand had to retransmit the unacknowledged frames. As for TCP, retransmitting these frames immediately upon expiration of a fixed timeout is not a good approach as several terminals may retransmit their frames at the same time leading to a network collapse. A better approach, but still far from perfect, is for each terminal to wait a random amount of time after the expiration of its retransmission timeout. This avoids synchronization among multiple retransmitting terminals. 1310/10000 · 1310
71 ../../principles/transport.rst:264
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — An invocation of the `connection-oriented service` is divided into three phases. The first phase is the establishment of a `connection`. A `connection` is a temporary association between two users through a service provider. Several connections may exist at the same time between any pair of users. Once established, the connection is used to transfer SDUs. `Connections` usually provide one bidirectional stream supporting the exchange of SDUs between the two users that are associated through the `connection`. This stream is used to transfer data during the second phase of the connection called the `data transfer` phase. The third phase is the termination of the connection. Once the users have finished exchanging SDUs, they request the service provider to terminate the connection. As we will see later, there are also some cases where the service provider may need to terminate a connection itself. 906/10000 · 906
72 ../../exercises/network.rst:391
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — After each update of a forwarding table, verify which pairs of routers are able to exchange packets. Provide your answer using a table similar to the one shown above. 166/10000 · 166
72 ../../glossary.rst:66
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Internet 8/10000 · 8
72 ../../principles/network.rst:420
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Each of the packet fragments is a valid packet that contains a header with the source (host `A`) and destination (host `B`) addresses. When router `R2` receives a packet fragment, it treats this packet as a regular packet and forwards it to its final destination (host `B`). Host `B` reassembles the received fragments. 319/10000 · 319
72 ../../principles/reliability.rst:257
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `BEL`: `0000111` b 18/10000 · 18
72 ../../principles/transport.rst:267
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The establishment of a connection can be modeled by using four primitives : `Connect.request`, `Connect.indication`, `Connect.response` and `Connect.confirm`. The `Connect.request` primitive is used to request the establishment of a connection. The main parameter of this primitive is the `address` of the destination user. The service provider delivers a `Connect.indication` primitive to inform the destination user of the connection attempt. If it accepts to establish a connection, it responds with a `Connect.response` primitive. At this point, the connection is considered to be established and the destination user can start sending SDUs over the connection. The service provider processes the `Connect.response` and will deliver a `Connect.confirm` to the user who initiated the connection. The delivery of this primitive terminates the connection establishment phase. At this point, the connection is considered to be open and both users can send SDUs. A successful connection establishment is illustrated below. 1021/10000 · 1021
72 ../../principles/security.rst:853
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Then, knowing Ted's public key, anyone can verify the validity of a certificate. When a user sends his/her public key, he/she must also attach the certificate to prove the link between his/her identity and the public key. In practice, certificates are more complex than this. Certificates will often be used to authenticate the server and sometimes to authenticate the client. 376/10000 · 376
72 ../../exercises/ipv6.rst:656
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — We start by creating the objects that correspond to the static routes on the three routers. The second argument of the ``addDaemon`` method is a list of ``StaticRoute`` objects. Each of these objects is created by specifying an IP prefix and a nexthop. 252/10000 · 252