msgid "" msgstr "" "Project-Id-Version: French (cnp3-ebook)\n" "Report-Msgid-Bugs-To: \n" "POT-Creation-Date: 2026-04-20 15:41+0200\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME \n" "Language-Team: French \n" "Language: fr\n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=UTF-8\n" "Content-Transfer-Encoding: 8bit\n" "Plural-Forms: nplurals=2; plural=n > 1;\n" "X-Generator: Weblate 5.14.3\n" #: ../../exercises/ipv6.rst:6 msgid "IPv6 Networks" msgstr "Réseaux IPv6" #: ../../exercises/ipv6.rst:9 msgid "Basic questions on IPv6 Networks" msgstr "" #: ../../exercises/ipv6.rst:11 msgid "" "Before starting to determine the paths that packets will follow in an IPv6 " "network, it is important to remember how to convert IPv6 addresses in binary " "numbers." msgstr "" #: ../../exercises/ipv6.rst:15 msgid "" "An IPv6 forwarding table contains a list of IPv6 prefixes with their " "associated nexthop or outgoing interface. When an IPv6 router receives a " "packet, it forwards it according to its forwarding table. Note that IPv6 " "routers forward packets along the *longest match* between the destination " "address of the packet and the routes in the forwarding table." msgstr "" #: ../../exercises/ipv6.rst:20 msgid "" "Now that you master the basics, you can determine the paths followed by IPv6 " "packets in simple networks." msgstr "" #: ../../exercises/ipv6.rst:31 msgid "Design questions" msgstr "" #: ../../exercises/ipv6.rst:33 #: ../../exercises/ipv6.rst:142 msgid "" "Consider the network shown in the figure below. In this network, the " "following addresses are used." msgstr "" #: ../../exercises/ipv6.rst:35 #: ../../exercises/ipv6.rst:144 #: ../../exercises/ipv6.rst:222 msgid "" "host ``A`` : ``2001:db8:1341:1::A`` and its default route points to " "``2001:db8:1341:1::1``" msgstr "" #: ../../exercises/ipv6.rst:36 #: ../../exercises/ipv6.rst:145 #: ../../exercises/ipv6.rst:223 msgid "" "host ``B`` : ``2001:db8:1341:4::B`` and its default route points to " "``2001:db8:1341:4::4``" msgstr "" #: ../../exercises/ipv6.rst:38 #: ../../exercises/ipv6.rst:147 #: ../../exercises/ipv6.rst:225 msgid "The routers have one address inside each network :" msgstr "" #: ../../exercises/ipv6.rst:40 #: ../../exercises/ipv6.rst:149 msgid "" "router ``R1`` uses address ``2001:db8:1341:1::1`` on its West interface, " "address ``2001:db8:1341:12::1`` on its East interface and address " "``2001:db8:1341:13::1`` on its South interface" msgstr "" #: ../../exercises/ipv6.rst:41 msgid "" "router ``R2`` uses address ``2001:db8:1341:12::2`` on its West interface, " "address ``2001:db8:1341:23::2`` on its South-West interface and address " "``2001:db8:1341:24::2`` on its South interface." msgstr "" #: ../../exercises/ipv6.rst:42 msgid "" "router ``R3`` uses address ``2001:db8:1341:34::3`` on its East interface, " "address ``2001:db8:1341:23::3`` on its North-East interface and address " "``2001:db8:1341:13::3`` on its North interface" msgstr "" #: ../../exercises/ipv6.rst:43 #: ../../exercises/ipv6.rst:152 msgid "" "router ``R4`` uses address ``2001:db8:1341:34::4`` on its West interface, " "address ``2001:db8:1341:24::4`` on its North interface and address " "``2001:db8:1341:4::4`` on its East interface" msgstr "" #: ../../exercises/ipv6.rst:45 msgid "" "The forwarding paths used in a network depend on the forwarding tables " "installed in the network nodes. Sometimes, these forwarding tables must be " "configured manually." msgstr "" #: ../../exercises/ipv6.rst:91 msgid "" "In this network, propose the forwarding tables of ``R2`` and ``R3`` that " "ensure that hosts ``A`` and ``B`` can exchange packets in both directions." msgstr "" #: ../../exercises/ipv6.rst:94 msgid "" "Consider the same network as in the previous question, but now the " "forwarding tables of ``R2`` and ``R3`` are configured as shown below :" msgstr "" #: ../../exercises/ipv6.rst:139 msgid "" "In this network, select `all` the rules in the shown forwarding tables that " "ensure that the packets sent from ``A`` to ``B`` follow the reverse path of " "the packets sent by ``B`` to ``A``." msgstr "" #: ../../exercises/ipv6.rst:150 #: ../../exercises/ipv6.rst:228 msgid "" "router ``R2`` uses address ``2001:db8:1341:12::2`` on its West interface, " "and address ``2001:db8:1341:24::2`` on its South interface" msgstr "" #: ../../exercises/ipv6.rst:151 #: ../../exercises/ipv6.rst:229 msgid "" "router ``R3`` uses address ``2001:db8:1341:34::3`` on its East interface and " "address ``2001:db8:1341:13::3`` on its North interface" msgstr "" #: ../../exercises/ipv6.rst:154 msgid "" "Routers ``R2`` and ``R3`` are buggy in this network. Besides the routes for " "their local interfaces (not shown in the figure), they only have a default " "route which is shown in the figure below." msgstr "" #: ../../exercises/ipv6.rst:193 msgid "" "How do you configure the forwarding tables on ``R1`` and ``R4`` so that ``A``" " can reach ``B`` and the reverse ?" msgstr "" #: ../../exercises/ipv6.rst:195 msgid "Consider a slightly different network than in the previous question." msgstr "" #: ../../exercises/ipv6.rst:220 msgid "Assuming that the following IPv6 addresses are used :" msgstr "" #: ../../exercises/ipv6.rst:227 msgid "" "router ``R1`` uses address ``2001:db8:1341:1::1`` on its West interface, " "address ``2001:db8:1341:12::1`` on its East interface, address " "``2001:db8:1341:14::1`` on its South-East interface and address " "``2001:db8:1341:13::1`` on its South interface" msgstr "" #: ../../exercises/ipv6.rst:230 msgid "" "router ``R4`` uses address ``2001:db8:1341:34::4`` on its West interface, " "address ``2001:db8:1341:24::4`` on its North interface, address " "``2001:db8:1341:14::4`` on its North-West interface and address " "``2001:db8:1341:4::4`` on its East interface" msgstr "" #: ../../exercises/ipv6.rst:232 msgid "" "Can you configure the forwarding tables so that the following paths are used " "by packets sent by host ``A`` to reach one of the four addresses of router " "``R4``?" msgstr "" #: ../../exercises/ipv6.rst:290 msgid "" "Do your forwarding tables impose the path used to reach host ``B`` which is " "attached to router ``R4`` or do you need to configure an additional entry in " "these tables ?" msgstr "" #: ../../exercises/ipv6.rst:292 msgid "" "Consider the network below that contains only routers. This network has been " "configured by a group of students and you must verify whether the " "configuration is correct. All the IPv6 addresses are part of the same ``/48``" " prefix that we name ``p``. The following subnets are defined in this ``/48``" " prefix." msgstr "" #: ../../exercises/ipv6.rst:294 msgid "" "``p:12/64`` for the link between ``R1`` and ``R2``. On this subnet, ``R1`` " "uses address ``p:12::1`` while router ``R2`` uses address ``p:12::2``" msgstr "" #: ../../exercises/ipv6.rst:295 msgid "" "``p:13/64`` for the link between ``R1`` and ``R3``. On this subnet, ``R1`` " "uses address ``p:13::1`` while router ``R3`` uses address ``p:13::3``" msgstr "" #: ../../exercises/ipv6.rst:296 msgid "" "``p:24/64`` for the link between ``R2`` and ``R4``. On this subnet, ``R2`` " "uses address ``p:24::2`` while router ``R4`` uses address ``p:24::4``" msgstr "" #: ../../exercises/ipv6.rst:297 msgid "..." msgstr "" #: ../../exercises/ipv6.rst:330 msgid "" "The students have configured the following forwarding tables on these six " "routers." msgstr "" #: ../../exercises/ipv6.rst:332 msgid "on router ``R1``" msgstr "" #: ../../exercises/ipv6.rst:350 msgid "on router ``R2``" msgstr "" #: ../../exercises/ipv6.rst:368 msgid "on router ``R3``" msgstr "" #: ../../exercises/ipv6.rst:384 msgid "on router ``R5``" msgstr "" #: ../../exercises/ipv6.rst:399 msgid "on router ``R4``" msgstr "" #: ../../exercises/ipv6.rst:416 msgid "on router ``R6``" msgstr "" #: ../../exercises/ipv6.rst:433 msgid "What do you think about the proposed configuration?" msgstr "" #: ../../exercises/ipv6.rst:436 msgid "" "Sometimes, static routes must be configured on networks to enforce certain " "paths. Consider the six routers network shown in the figure below." msgstr "" #: ../../exercises/ipv6.rst:471 msgid "In this network, we will focus on four IPv6 prefixes :" msgstr "" #: ../../exercises/ipv6.rst:473 msgid "" "``p:0000::/64`` used on the link ``A1-R1``. ``A1`` uses address ``p:0000::A1/" "64``" msgstr "" #: ../../exercises/ipv6.rst:474 msgid "" "``p:0001::/64`` used on the link ``A2-R3``. ``A2`` uses address ``p:0001::A2/" "64``" msgstr "" #: ../../exercises/ipv6.rst:475 msgid "" "``p:0002::/64`` used on the link ``B1-R5``. ``B1`` uses address ``p:0002::B1/" "64``" msgstr "" #: ../../exercises/ipv6.rst:476 msgid "" "``p:0003::/64`` used on the link ``B2-R6``. ``B2`` uses address ``p:0003::B2/" "64``" msgstr "" #: ../../exercises/ipv6.rst:478 msgid "" "Can you configure the forwarding tables of the six routers to achieve the " "following network objectives :" msgstr "" #: ../../exercises/ipv6.rst:480 msgid "" "All packets sent by ``B1`` and ``B2`` to ``A1`` and ``A2`` are always " "forwarded via ``R2`` while all packets from ``A1`` and ``A2`` are always " "forwarded via ``R4``" msgstr "" #: ../../exercises/ipv6.rst:481 msgid "" "The packets whose destinations are ``A1``, ``A2``, ``B1`` or ``B2`` are " "never forwarded via router ``R4``" msgstr "" #: ../../exercises/ipv6.rst:482 msgid "" "The packets sent by ``A1`` or ``A2`` towards ``B1`` are always forwarded via " "``R2`` while the packets towards ``B2`` are always forwarded via ``R4``." msgstr "" #: ../../exercises/ipv6.rst:484 msgid "" "When creating these forwarding tables, try to minimize the number of entries " "that you install on each router." msgstr "" #: ../../exercises/ipv6.rst:486 msgid "" "When a network is designed, an important element of the design is the IP " "address allocation plan. A good allocation plan can provide flexibility and " "help to reduce the size of the forwarding tables." msgstr "" #: ../../exercises/ipv6.rst:517 msgid "" "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." msgstr "" #: ../../exercises/ipv6.rst:527 msgid "Configuring IPv6 Networks" msgstr "" #: ../../exercises/ipv6.rst:529 msgid "" "With the previous exercises, you have learned how to reason about IPv6 " "networks \"on paper\". Given the availability of IPv6 implementations, it is " "also possible to carry out experiments in real and virtual labs. Several " "virtual environments are possible. In this section, we focus on mininet_. " "mininet_ is an emulation framework developed at Stanford University that " "leverages the namespaces features of recent Linux kernels. With those " "namespaces, a single Linux kernel can support a variety of routers and hosts " "interconnected by virtual links. mininet_ has been used by several " "universities as an educational tool, but unfortunately it was designed " "without IPv6 support." msgstr "" #: ../../exercises/ipv6.rst:531 msgid "" "During the last years, `Olivier Tilmans `_ and `Mathieu Jadin `" "_ 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." msgstr "" #: ../../exercises/ipv6.rst:533 msgid "" "The syntax of IPMininet_ is relatively simple and can be learned by looking " "at a few examples." msgstr "" #: ../../exercises/ipv6.rst:535 msgid "" "Let us start our exploration of IPv6 routing with a simple network topology " "that contains two hosts and three routers and uses static routes." msgstr "" #: ../../exercises/ipv6.rst:580 msgid "" "IPMininet_ simplifies the creation of the network topology by providing a " "simple API. For this, you simply need to declare a class that extends the " "``IPTopo`` class." msgstr "" #: ../../exercises/ipv6.rst:592 msgid "" "Then, you need to extend the build method that creates routers and hosts." msgstr "" #: ../../exercises/ipv6.rst:607 msgid "" "Although IPMininet_ can assign prefixes and addresses automatically, we use " "manually assigned addresses in this example." msgstr "" #: ../../exercises/ipv6.rst:609 msgid "We use five /64 IPv6 prefixes in this network topology:" msgstr "" #: ../../exercises/ipv6.rst:611 msgid "``2001:db8:1341:1::/64`` on the link between ``a`` and ``r1``" msgstr "" #: ../../exercises/ipv6.rst:612 msgid "``2001:db8:1341:12::/64`` on the link between ``r1`` and ``r2``" msgstr "" #: ../../exercises/ipv6.rst:613 msgid "``2001:db8:1341:13::/64`` on the link between ``r1`` and ``r3``" msgstr "" #: ../../exercises/ipv6.rst:614 msgid "``2001:db8:1341:23::/64`` on the link between ``r2`` and ``r3``" msgstr "" #: ../../exercises/ipv6.rst:615 msgid "``2001:db8:1341:1::/64`` on the link between ``b`` and ``r3``" msgstr "" #: ../../exercises/ipv6.rst:617 msgid "" "We can then manually configure the IPv6 addresses of each host/router on " "each link. Let us start with the links attached to the two hosts." msgstr "" #: ../../exercises/ipv6.rst:631 msgid "The same can be done for the three links between the different routers." msgstr "" #: ../../exercises/ipv6.rst:648 msgid "" "With these IP prefixes and the network topology, we can now use IPMininet_ " "to create the topology and assign the addresses." msgstr "" #: ../../exercises/ipv6.rst:656 msgid "" "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." msgstr "" #: ../../exercises/ipv6.rst:675 msgid "We can now create the hosts and the routers" msgstr "" #: ../../exercises/ipv6.rst:682 msgid "" "With this ``build`` method, we can now launch the network by using the " "python code below." msgstr "" #: ../../exercises/ipv6.rst:694 msgid "" "The entire script is available from :download:`/exercises/ipmininet_scripts/" "static-1.py`." msgstr "" #: ../../exercises/ipv6.rst:696 msgid "" "To help students to start using IPMininet, `Mathieu Jadin `_ has created a Vagrant box that launches a " "Ubuntu virtual machine with all the required software. See https://" "ipmininet.readthedocs.io/en/latest/install.html for additional information." msgstr "" #: ../../exercises/ipv6.rst:698 msgid "Here is a simple example of the utilization of this Vagrant box." msgstr "" #: ../../exercises/ipv6.rst:700 msgid "" "We start the network topology shown above with the ``sudo python script.py`` " "command. It launches the mininet_ interactive shell that provides several " "useful commands:" msgstr "" #: ../../exercises/ipv6.rst:732 msgid "" "Some of the standard mininet commands assume the utilisation of IPv4 and do " "not have a direct IPv6 equivalent. Here are some useful commands." msgstr "" #: ../../exercises/ipv6.rst:734 msgid "" "The ``nodes`` command lists the routers and hosts that have been created in " "the mininet topology." msgstr "" #: ../../exercises/ipv6.rst:743 msgid "" "The ``links`` command lists the links that have been instantiated and shows " "that mapping between the named interfaces on each node." msgstr "" #: ../../exercises/ipv6.rst:760 msgid "" "It is possible to execute any of the standard Linux commands to configure " "the network stack on any of the hosts by prefixing the command with the " "corresponding host. Remember to always specify ``inet6`` as the address " "family to retrieve the IPv6 information." msgstr "" #: ../../exercises/ipv6.rst:770 msgid "" "Host ``a`` has two interfaces: the standard loopback interface and a network " "interface named ``a-eth0`` that is attached to router ``r1``. We can also " "verify how the IPv6 addresses have been configured:" msgstr "" #: ../../exercises/ipv6.rst:784 msgid "" "On its ``a-eth0`` interface, host ``a`` uses IPv6 address ``2001:db8:1341:1::" "a/64``. The link local address (``fe80::c44e:26ff:fed9:de6d/64``) will be " "described in another chapter. Finally, we can check the forwarding table of " "host ``a``." msgstr "" #: ../../exercises/ipv6.rst:794 msgid "" "There are three routes in this table. The first two correspond to the two " "prefixes that are used over the ``a-eth0`` interface. These routes are " "automatically created when an IPv6 address is configured on an interface. " "The last route is the default route (``::/0``) which points towards " "``2001:db8:1341:1::1``, i.e. router ``r1``." msgstr "" #: ../../exercises/ipv6.rst:796 msgid "" "Another useful command is ``xterm`` 'node' that allows to launch a terminal " "on the specified node. This gives you a interactive shell on any node. You " "can use it to capture packets with tcpdump_. As an example, let us use " ":manpage:`traceroute6(8)` to trace the path followed by packets from host " "``a`` towards the IPv6 address of host ``b`` i.e. ``2001:db8:1341:3::b``. " "The output of this command shows that the path passes through routers ``r1``" ", ``r2`` and ``r3``." msgstr "" #: ../../exercises/ipv6.rst:808 msgid "" "Another interesting mininet_ command is ``pingall`` it allows to check that " "any host can reach any other host inside the network. It executes a ping " "from any host to any other host inside the network topology." msgstr "" #: ../../exercises/ipv6.rst:819 msgid "" "When debugging a network, it can be interesting to capture packets using " "tcpdump_ on specific links to check that they follow the expect. If you use " "tcpdump_ without any filter, you will capture the packets generated by " "xterm. To capture packets, you need to specify precise filters that will " "match the packets of interest. For traceroute6, you need to match the IPv6 " "packets that contain UDP segments and some ICMPv6 packets. The script below " "provides a simple filter that you can reuse. It takes one argument: the name " "of the interface on which tcpdump_ needs to run." msgstr "" #: ../../exercises/ipv6.rst:827 msgid "" "Starting from the :download:`/exercises/ipmininet_scripts/static-1.py` " "IPMininet_ script, we can explore classical problems when networks are " "configured with static routes. A first problem is when a router has an " "incomplete forwarding table. We configure the static routes as shown below. " "The entire script is available from :download:`/exercises/ipmininet_scripts/" "static-1-hole.py`." msgstr "" #: ../../exercises/ipv6.rst:841 msgid "We first check with ``pingall`` whether the network works correctly." msgstr "" #: ../../exercises/ipv6.rst:851 msgid "The problem can be detected by using :manpage:`traceroute6(8)`." msgstr "" #: ../../exercises/ipv6.rst:861 msgid "" "In the output of :manpage:`traceroute6(8)`, a ``!N`` indicates that host " "``a`` received from ``2001:db8:1341:12::2``, i.e. router ``r2``, a Network " "unreachable ICMPv6 message. The forwarding table of ``r2`` confirms the root " "cause of this problem." msgstr "" #: ../../exercises/ipv6.rst:873 msgid "" "A second problem is when there is a forwarding loop inside the network, i.e. " "packets sent to a specific destination loop through several routers. With " "the static routes shown below, router ``r2`` forwards the packets towards " "``2001:db8:1341:3::b`` via router ``r1``. The entire script is available " "from :download:`/exercises/ipmininet_scripts/static-1-loop.py`." msgstr "" #: ../../exercises/ipv6.rst:888 msgid "" "The ``pingall`` command reveals that there is a problem in this network." msgstr "" #: ../../exercises/ipv6.rst:898 msgid "" "We can analyze this configuration problem in more details by using " "``traceroute6``. The loop appears clearly." msgstr "" #: ../../exercises/ipv6.rst:919 msgid "" "On host ``b``, the problem is different. The packets that it sends towards " "host ``a`` do not seem to go beyond router ``r3``." msgstr "" #: ../../exercises/ipv6.rst:933 msgid "" "To debug this problem, let us look at the forwarding table of ``r3``. This " "router forwards the packets sent to host ``a`` to router ``r1`` that is " "directly connected to host ``a``." msgstr "" #: ../../exercises/ipv6.rst:946 msgid "" "Unfortunately, when router ``r1`` sends its ICMP HopLimit exceeded message, " "the destination of this IP packet is ``2001:db8:1341:3::b``. This packet is " "forward to router ``r2`` that returns the packet back to router ``r1``. The " "packet loops between the two routers until their HopLimit reaches zero." msgstr "" #: ../../exercises/ipv6.rst:965 msgid "IPv6 packets" msgstr "" #: ../../exercises/ipv6.rst:967 msgid "" "To correctly understand the operation of IPv6, it is sometimes important to " "remember the packet format and how the different fields are used." msgstr "" #: ../../exercises/ipv6.rst:971 msgid "" "The `Next Header` of the IPv6 packet indicates the type of the header that " "follows the IPv6 packet. IANA_ maintains a list of all the assigned values " "of this header at https://www.iana.org/assignments/protocol-numbers/protocol-" "numbers.xhtml" msgstr "" #: ../../exercises/ipv6.rst:980 msgid "" "When an IPv6 router receives a packet that is larger than the Maximum " "Transmission Unit (MTU) on its outgoing interface, it drops the packet and " "returns an ICMPv6 message back to the source. Upon reception of this ICMPv6 " "message, the source will either adjust the size of the packets that it " "transmits or use IPv6 packet fragmentation. The exercises below show a few " "examples of the utilization of IPv6 fragmentation." msgstr "" #: ../../exercises/ipv6.rst:987 msgid "" "Network engineers often rely on :manpage:`ping6(8)` to verify the " "reachability of a remote host or router. :manpage:`ping6(8)` sends ICMPv6 " "echo request messages and analyzes the received ICMPv6 echo responses. Each " "echo request message contains an identifier and a sequence number that is " "returned in the response." msgstr "" #: ../../exercises/ipv6.rst:991 msgid "" "When the :manpage:`ping6(8)` is executed, it sends ICMPv6 echo request " "messages with increasing sequence numbers." msgstr "" #: ../../exercises/ipv6.rst:995 msgid "" "The :manpage:`traceroute6(8)` software is very useful to debug network " "problems. It sends a series of UDP segments encapsulated inside IP packets " "with increasing values of the HopLimit. The first packet has a HotLimit and " "the first router on the path returns an ICMPv6 HopLimit exceeded message." msgstr "" #: ../../exercises/ipv6.rst:999 msgid "" "When :manpage:`traceroute6(8)` sends UDP segments, it uses the UDP source " "port as a way to remember the target hop for this specific UDP segment." msgstr ""