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57 ../../exercises/network.rst:374
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — C 1/10000 · 1
57 ../../glossary.rst:179
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A relay operating in the physical layer. 40/10000 · 40
57 ../../principles/network.rst:345
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The last, but important, point to discuss about the `data plane` of the networks that rely on the datagram mode is their addressing scheme. In the examples above, we have used letters to represent the addresses of the hosts and network nodes. In practice, all addresses are encoded as a bit string. Most network technologies use a fixed size bit string to represent source and destination address. These addresses can be organized in two different ways. 453/10000 · 453
57 ../../principles/reliability.rst:232
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 01111110011011111011111011111011001001111110 44/10000 · 44
57 ../../principles/sharing.rst:374
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The common problem among Local Area Networks is how to efficiently share the available bandwidth. If two devices send a frame at the same time, the two electrical, optical or radio signals that correspond to these frames will appear at the same time on the transmission medium and a receiver will not be able to decode either frame. Such simultaneous transmissions are called `collisions`. A `collision` may involve frames transmitted by two or more devices attached to the Local Area Network. Collisions are the main cause of errors in wired Local Area Networks. 563/10000 · 563
57 ../../principles/transport.rst:234
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — As the transport layer is built on top of the network layer, it is important to know the key features of the network layer service. In this book, we only consider the `connectionless network layer service` which is the most widespread. Its main characteristics are : 266/10000 · 266
57 ../../principles/security.rst:600
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Public key cryptography provides another possibility to allow Alice to authenticate herself on Bob's computer. Assume again that Alice and Bob know each other from previous encounters. Alice knows Bob's public key (:math:`Bob_{pub}`) and Bob also knows Alice's key (:math:`Alice_{pub}`). To authenticate herself, Alice could send her user identifier. Bob would reply with a random number encrypted with Alice's public key : :math:`E_p(Alice_{pub},R)`. Alice can decrypt this message to recover `R` and sends :math:`E_p(Bob_{pub},R)`. Bob decrypts the nonce and confirms that Alice knows :math:`Alice_{priv}`. If an eavesdropper captures the messages exchanged, he cannot recover the value `R` which could be used as a key to encrypt the information with a secret key algorithm. This is illustrated in the time sequence diagram below. 833/10000 · 833
57 ../../exercises/ipv6.rst:531
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — During the last years, `Olivier Tilmans <https://inl.info.ucl.ac.be/otilmans.html>`_ and `Mathieu Jadin <https://inl.info.ucl.ac.be/mjadin.html>`_ have developed the missing piece to enable students to use mininet_ to experiment with IPv6: ipmininet_. ipmininet_ is a python module that provides the classes that are required to automatically configure IPv6 networks with different routing protocols. It is available from PyPi from https://pypi.python.org/ipmininet. 467/10000 · 467
57 ../../exercises/routing-protocols.rst:840
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the eBGP session with ``fe80::3c81:2eff:fe19:465d`` with an AS-Path of ``AS3:AS2`` (see last column) 100/10000 · 100
57 ../../exercises/tcp-2.rst:715
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Same question as the first one, but consider that the MSS on the sender is set to 500 bytes. How does this modification affect the entire delay ? 145/10000 · 145
57 ../../protocols/bgp.rst:197
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — At this point, the remote router has received all the exportable BGP routes. After this initial exchange, the router only sends `BGP UPDATE` messages when there is a change (addition of a route, removal of a route or change in the attributes of a route) in one of these exportable routes. Such a change can happen when the router receives a BGP message. The pseudo-code below summarizes the processing of these BGP messages. 424/10000 · 424
57 ../../protocols/congestion.rst:242
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The buffers of a router can be implemented as variable or fixed-length slots. If the router uses variable length slots to store the queued packets, then the occupancy is usually measured in bytes. Some routers have use fixed-length slots with each slot large enough to store a maximum-length packet. In this case, the buffer occupancy is measured in packets. 358/10000 · 358
57 ../../protocols/email.rst:232
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 51 2/10000 · 2
57 ../../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
57 ../../protocols/http.rst:190
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — All status codes starting with digit `5` indicate an error on the server. `500 Internal Server Error` indicates that the server could not process the request due to an error on the server itself. 195/10000 · 195
57 ../../protocols/ipv6.rst:189
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — There is one difficulty with the utilization of these IPv6 prefixes. Consider Belnet, the Belgian research ISP that has been allocated the ``2001:6a8::/32`` prefix. Universities are connected to Belnet. UCLouvain uses prefix ``2001:6a8:3080::/48`` while the University of Liege uses ``2001:6a8:2d80::/48``. A commercial ISP uses prefix ``2a02:2788::/32``. Both Belnet and the commercial ISP are connected to the global Internet. 429/10000 · 429
57 ../../protocols/ethernet.rst:178
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 1000Base-SX 11/10000 · 11
57 ../../protocols/routing.rst:175
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The OSPF Designated Router election procedure is defined in :rfc:`2328`. Each router can be configured with a router priority that influences the election process since the router with the highest priority is preferred when an election is run. 243/10000 · 243
57 ../../protocols/tcp.rst:200
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — To avoid the `SYN flood` attacks, recent TCP implementations no longer enter the `SYN Rcvd` state upon reception of a `SYN segment`. Instead, they reply directly with a `SYN+ACK` segment and wait until the reception of a valid `ACK`. This implementation trick is only possible if the TCP implementation is able to verify that the received `ACK` segment acknowledges the `SYN+ACK` segment sent earlier without storing the initial sequence number of this `SYN+ACK` segment in a TCB. The solution to solve this problem, which is known as `SYN cookies <http://cr.yp.to/syncookies.html>`_ is to compute the 32 bits of the `ISN` as follows : 635/10000 · 635
57 ../../protocols/tls.rst:299
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A TLS cipher suite is usually represented as an ASCII string that starts with TLS and contains the acronym of the key exchange algorithm, the encryption scheme with the key size and its mode of operation and the authentication algorithm. For example, ``TLS_DHE_RSA_WITH_AES_128_GCM_SHA256`` is a TLS cipher suite that uses the ``DHE_RSA`` key exchange algorithm with 128 bits AES in GCM mode for encryption and SHA-256 for authentication. The official list of TLS cipher suites is maintained by IANA [#fianaTLS]_. The NULL acronym indicates that no algorithm has been specified. For example, ``TLS_ECDH_RSA_WITH_NULL_SHA`` is a cipher suite that does not use any encryption but still uses the ``ECDH_RSA`` key exchange and ``SHA`` for authentication. 750/10000 · 750