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66 ../../protocols/ethernet.rst:199
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The attentive reader may question the need for different `EtherTypes` for IPv4 and IPv6 while the IP header already contains a version field that can be used to distinguish between IPv4 and IPv6 packets. Theoretically, IPv4 and IPv6 could have used the same `EtherType`. Unfortunately, developers of the early IPv6 implementations found that some devices did not check the version field of the IPv4 packets that they received and parsed frames whose `EtherType` was set to `0x0800` as IPv4 packets. Sending IPv6 packets to such devices would have caused disruptions. To avoid this problem, the IETF decided to apply for a distinct `EtherType` value for IPv6. Such a choice is now mandated by :rfc:`6274` (section 3.1), although we can find a funny counter-example in :rfc:`6214`. 779/10000 · 779
66 ../../protocols/tcp.rst:223
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The TCP options are encoded by using a Type Length Value format where : 71/10000 · 71
66 ../../protocols/tls.rst:341
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — TLS supports several methods to encrypted records. The selected method depends on the cryptographic algorithms that have been negotiated for the TLS session. A detailed presentation of the different methods that can be used to produce the `TLSPlainText` from the user data is outside the scope of this book. As an example, we study one method: Stream Encryption. This method is used with cryptographic algorithms which can operate on a stream of bytes. The method starts with a sequence of bytes provided by the user application: the plain text. The first step is to compute the authentication code to verify the integrity of the data. For this, TLS computes :math:`MAC(SeqNum, Header, PlainText)` using HMAC where `SeqNum` is a sequence number which is incremented by one for each new TLS record transmitted. The `Header` is the header of the TLS record described above and `PlainText` is the information that needs to be encrypted. Note that the sequence number is maintained at the two endpoints of the TLS session, but it is not transmitted inside the TLS record. This sequence number is used to prevent replay attacks. 1123/10000 · 1123
66 ../../bibliography.rst:87
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Griffin, T. G. and Wilfong, G., `An analysis of BGP convergence properties <http://doi.acm.org/10.1145/316194.316231>`_. SIGCOMM Computer Communication Review 29, 4 (Oct. 1999), 277-288. 186/10000 · 186
67 ../../exercises/network.rst:381
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Consider a distance vector protocol using split horizon and `periodic updates`. Assume that the link `B-C` fails. `B` and `C` update their local routing table but they will only advertise it at the end of their period. Select one ordering for the `periodic updates` and every time a router sends its distance vector, indicate the vector sent to each neighbor and update the table above. How many periods are required to allow the network to converge to a stable state ? 470/10000 · 470
67 ../../bibliography.rst:89
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Garcia-Lunes-Aceves, J., `Loop-Free Routing Using Diffusing Computations <https://dx.doi.org/10.1109/90.222913>`_, IEEE/ACM Transactions on Networking, Vol. 1, No, 1, Feb. 1993 176/10000 · 176
67 ../../glossary.rst:146
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Interior Gateway Protocol. Synonym of intradomain routing protocol 66/10000 · 66
67 ../../principles/network.rst:392
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Sometimes, the network layer needs to deal with heterogeneous datalink layers. For example, two hosts connected to different datalink layers exchange packets via routers that are using other types of datalink layers. Thanks to the network layer, this exchange of packets is possible provided that each packet can be placed inside a datalink layer frame before being transmitted. If all datalink layers support the same frame size, this is simple. When a node receives a frame, it decapsulates the packet that it contains, checks the header and forwards it, encapsulated inside another frame, to the outgoing interface. Unfortunately, the encapsulation operation is not always possible. Each datalink layer is characterized by the maximum frame size that it supports. Datalink layers typically support frames containing up to a few hundreds or a few thousands of bytes. The maximum frame size that a given datalink layer supports depends on its underlying technology. Unfortunately, most datalink layers support a different maximum frame size. This implies that when a host sends a large packet inside a frame to its nexthop router, there is a risk that this packet will have to traverse a link that is not capable of forwarding the packet inside a single frame. In principle, there are three possibilities to solve this problem. To discuss them, we consider a simple scenario with two hosts connected to a router as shown in the figure below. 1442/10000 · 1442
67 ../../principles/reliability.rst:250
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `z` : `1111010` b 17/10000 · 17
67 ../../principles/sharing.rst:440
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — TDM as shown above can be completely static, i.e. the same conversations always share the link, or dynamic. In the latter case, the two endpoints of the link must exchange messages specifying which conversation uses which byte inside each slot. Thanks to these control messages, it is possible to dynamically add and remove voice conversations from a given link. 362/10000 · 362
67 ../../principles/transport.rst:252
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the `request-response service` 30/10000 · 30
67 ../../principles/security.rst:822
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — In this example, Mallory has forced Alice to compute :math:`E_p(Alice_{priv},RB)` which is the information required to finalize the first exchange and be authenticated as Alice. This illustrates a common problem with authentication schemes when the same information can be used for different purposes. The problem comes from the fact that Alice agrees to compute her signature on a nonce chosen by Bob (and relayed by Mallory). This problem occurs if the nonce is a simple integer without any structure. If the nonce includes some structure such as some information about Alice and Bob's identities or even a single bit indicating whether the nonce was chosen by a user acting as a client (i.e. starting the authentication) or as a server, then the protocol is not vulnerable anymore. 784/10000 · 784
67 ../../exercises/ipv6.rst:614
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — ``2001:db8:1341:23::/64`` on the link between ``r2`` and ``r3`` 63/10000 · 63
67 ../../exercises/routing-protocols.rst:911
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — We start indicate that we will use the terminal to change the router configuration with `configure terminal`. We then enter the BGP part of the configuration with `router bgp 2` (`2` is the AS number of `as2`). Then we use the `neighbor 2001:cafe:2:23::3 shutdown` that takes as parameter the IP address of the peer of the session that we want to stop. We then leave the BGP part of the configuration (first `exit`) and the configuration menu (second `exit` command). At this point, the BGP session between ``AS2`` and ``AS3`` is down. 535/10000 · 535
67 ../../exercises/tcp-2.rst:885
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — By default, packetdrill_ uses port 8080 when creating TCP segments. You can thus capture the packets injected by packetdrill_ and the responses from the stack by using ``tcpdump -i any -n port 8080`` 199/10000 · 199
67 ../../protocols/bgp.rst:282
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the `BGP nexthop` 17/10000 · 17
67 ../../protocols/email.rst:236
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — C 1/10000 · 1
67 ../../protocols/ethernet.rst:309
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The first Ethernet relays that operated in the datalink layers were called `bridges`. In practice, the main difference between switches and bridges is that bridges were usually implemented in software while switches are hardware-based devices. Throughout this text, we always use `switch` when referring to a relay in the datalink layer, but you might still see the word `bridge`. 380/10000 · 380
67 ../../protocols/http.rst:311
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The example below shows the operation of HTTP/1.1 over a persistent TCP connection to retrieve three URIs stored on the same server. Once the connection has been established, the client sends its first request with the `Connection: Keep-Alive` header to request a persistent connection. 286/10000 · 286
67 ../../protocols/ipv6.rst:230
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — For the companies that want to use IPv6 without being connected to the IPv6 Internet, :rfc:`4193` defines the `Unique Local Unicast (ULA)` addresses (``fc00::/7``). These ULA addresses play a similar role as the private IPv4 addresses defined in :rfc:`1918`. However, the size of the ``fc00::/7`` address block allows ULA to be much more flexible than private IPv4 addresses. 375/10000 · 375