# SOME DESCRIPTIVE TITLE. # Copyright (C) 2019 Olivier Bonaventure # This file is distributed under the same license as the Computer networking # : Principles, Protocols and Practice package. # FIRST AUTHOR , 2019. # #, fuzzy msgid "" msgstr "" "Project-Id-Version: Computer networking : Principles, Protocols and " "Practice 3\n" "Report-Msgid-Bugs-To: \n" "POT-Creation-Date: 2019-10-09 12:39+0000\n" "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n" "Last-Translator: FULL NAME \n" "Language-Team: LANGUAGE \n" "MIME-Version: 1.0\n" "Content-Type: text/plain; charset=utf-8\n" "Content-Transfer-Encoding: 8bit\n" "Generated-By: Babel 2.7.0\n" #: ../../exercises/network.rst:8 msgid "" "This is an unpolished draft of the third edition of this e-book. If you " "find any error or have suggestions to improve the text, please create an " "issue via https://github.com/CNP3/ebook/issues?milestone=2 or help us by " "providing pull requests to close the existing issues." msgstr "" #: ../../exercises/network.rst:12 msgid "Network : Open questions" msgstr "" #: ../../exercises/network.rst:14 msgid "" "In your daily life, you also use hierarchical and flat address spaces. " "Can you provide examples of these two types of addresses and discuss the " "benefits of using a hierarchical or flat addressing space in this " "particular context ?" msgstr "" #: ../../exercises/network.rst:16 msgid "" "The network below uses port forwarding with flat addresses. The network " "boots and all hosts start one after the other. Explain at each step how " "the packets are forwarded and how the port forwarding tables of the " "network nodes are modified. Host `C` sends a packet to host `B`. Some " "time later, host `A` sends a packet to host `C`. Finally, host `B` sends " "a packet to host `A`." msgstr "" #: ../../exercises/network.rst:42 msgid "" "Same question as above, but the network is modified as shown in the " "figure below." msgstr "" #: ../../exercises/network.rst:67 msgid "" "Routing protocols used in data networks only use positive link weights. " "What would happen with a distance vector routing protocol in the network " "below that contains a negative link weight ?" msgstr "" #: ../../exercises/network.rst:86 msgid "" "When a network specialist designs a network, one of the problems that he " "needs to solve is to set the metrics the links in his network. In the " "USA, the Abilene network interconnects most of the research labs and " "universities. The figure below shows the topology of this network in " "2009." msgstr "" #: ../../exercises/network.rst:92 msgid "The Abilene network" msgstr "" #: ../../exercises/network.rst:94 msgid "" "In this network, assume that all the link weights are set to 1. What is " "the paths followed by a packet sent by the router located in `Los " "Angeles` to reach :" msgstr "" #: ../../exercises/network.rst:96 msgid "the router located in `New York`" msgstr "" #: ../../exercises/network.rst:97 msgid "the router located in `Washington` ?" msgstr "" #: ../../exercises/network.rst:99 msgid "" "Is it possible to configure the link metrics so that the packets sent by " "the router located in `Los Angeles` to the routers located in " "respectively `New York` and `Washington` do not follow the same path ?" msgstr "" #: ../../exercises/network.rst:101 msgid "" "Is it possible to configure the link weights so that the packets sent by " "the router located in `Los Angeles` to router located in `New York` " "follow one path while the packets sent by the router located in `New " "York` to the router located in `Los Angeles` follow a completely " "different path ?" msgstr "" #: ../../exercises/network.rst:103 msgid "" "Assume that the routers located in `Denver` and `Kansas City` need to " "exchange lots of packets. Can you configure the link metrics such that " "the link between these two routers does not carry any packet sent by " "another router in the network ?" msgstr "" #: ../../exercises/network.rst:105 msgid "" "In the five nodes network shown below, can you configure the link metrics" " so that the packets sent by router `E` to router `A` use link `B->A` " "while the packets sent by router `B` use links `B->D` and `D->A`?" msgstr "" #: ../../exercises/network.rst:129 msgid "" "In the five nodes network shown above, can you configure the link weights" " so that the packets sent by router `E` (resp. `F`) follow the `E->B->A` " "path (resp. `F->D->B->A`) ?" msgstr "" #: ../../exercises/network.rst:132 ../../exercises/network.rst:154 #: ../../exercises/network.rst:184 ../../exercises/network.rst:216 msgid "Consider the network shown in the figure below." msgstr "" #: ../../exercises/network.rst:152 msgid "" "Assuming that the network uses source routing, what are the possible " "paths from `R1` to `R4` ?" msgstr "" #: ../../exercises/network.rst:176 msgid "" "The network operator uses would like to have the following paths in this " "network :" msgstr "" #: ../../exercises/network.rst:178 msgid "`R3->R2->R4->R5` and `R1->R2->R5`" msgstr "" #: ../../exercises/network.rst:180 msgid "" "Is it possible to achieve these paths and if so what are the required " "forwarding tables ?" msgstr "" #: ../../exercises/network.rst:182 ../../exercises/network.rst:214 msgid "Same question with virtual circuits." msgstr "" #: ../../exercises/network.rst:208 ../../exercises/network.rst:238 msgid "The network operator would like to use the following paths :" msgstr "" #: ../../exercises/network.rst:210 msgid "`R1->R2->R4` and `R3->R2->R5->R4`" msgstr "" #: ../../exercises/network.rst:212 ../../exercises/network.rst:242 msgid "" "Are these paths possible with link-state or distance vector routing ? If " "yes, how do configure the link weights. If no, explain your answer." msgstr "" #: ../../exercises/network.rst:240 msgid "`R1->R5->R4` and `R3->R2->R4`" msgstr "" #: ../../exercises/network.rst:247 msgid "Network: Discussion questions" msgstr "" #: ../../exercises/network.rst:250 msgid "" "The network below uses port forwarding tables. It has been running for " "several hours and all hosts have exchanged packets. What is the content " "of the port forwarding tables ?" msgstr "" #: ../../exercises/network.rst:273 msgid "" "At this point, a new link is added between `R1` and `R3`. What happens " "for the forwarding of packets ?" msgstr "" #: ../../exercises/network.rst:276 msgid "" "The network below uses port forwarding tables. What happens if host `A` " "moves by removing its link with `R1` and replacing it with a link with " "`R3`? How should networks using port forwarding deal with such mobile " "hosts ?" msgstr "" #: ../../exercises/network.rst:299 msgid "" "Some hosts need to be multihomed, i.e. attached to two different network " "nodes as shown in the figure below." msgstr "" #: ../../exercises/network.rst:323 msgid "Would this network work correctly with port-forwarding tables if :" msgstr "" #: ../../exercises/network.rst:325 msgid "Host `A` uses the same flat address for both links." msgstr "" #: ../../exercises/network.rst:326 msgid "Host `A` uses a different flat address on each of its links" msgstr "" #: ../../exercises/network.rst:328 msgid "" "What are the advantages and drawbacks of flat addresses versus " "hierarchical addresses ?" msgstr "" #: ../../exercises/network.rst:332 msgid "" "Let us now consider the transient problems that mainly happen when the " "network topology changes. For this, consider the network topology shown " "in the figure below and assume that all routers use a distance vector " "protocol that uses split horizon." msgstr "" #: ../../exercises/network.rst:356 msgid "" "If you compute the routing tables of all routers in this network, you " "would obtain a table such as the table below :" msgstr "" #: ../../exercises/network.rst:360 msgid "Destination" msgstr "" #: ../../exercises/network.rst:360 msgid "Routes on A" msgstr "" #: ../../exercises/network.rst:360 msgid "Routes on B" msgstr "" #: ../../exercises/network.rst:360 msgid "Routes on C" msgstr "" #: ../../exercises/network.rst:360 msgid "Routes on D" msgstr "" #: ../../exercises/network.rst:360 msgid "Routes on E" msgstr "" #: ../../exercises/network.rst:363 msgid "A" msgstr "" #: ../../exercises/network.rst:363 ../../exercises/network.rst:364 #: ../../exercises/network.rst:365 ../../exercises/network.rst:366 #: ../../exercises/network.rst:367 msgid "0" msgstr "" #: ../../exercises/network.rst:363 msgid "1 via A" msgstr "" #: ../../exercises/network.rst:363 ../../exercises/network.rst:365 msgid "2 via B" msgstr "" #: ../../exercises/network.rst:363 ../../exercises/network.rst:367 msgid "3 via C" msgstr "" #: ../../exercises/network.rst:363 msgid "4 via D" msgstr "" #: ../../exercises/network.rst:364 msgid "B" msgstr "" #: ../../exercises/network.rst:364 msgid "1 via B" msgstr "" #: ../../exercises/network.rst:364 ../../exercises/network.rst:366 msgid "2 via C" msgstr "" #: ../../exercises/network.rst:364 msgid "3 via D" msgstr "" #: ../../exercises/network.rst:365 msgid "C" msgstr "" #: ../../exercises/network.rst:365 msgid "1 via C" msgstr "" #: ../../exercises/network.rst:365 ../../exercises/network.rst:367 msgid "2 via D" msgstr "" #: ../../exercises/network.rst:366 msgid "D" msgstr "" #: ../../exercises/network.rst:366 msgid "3 via B" msgstr "" #: ../../exercises/network.rst:366 msgid "1 via D" msgstr "" #: ../../exercises/network.rst:367 msgid "E" msgstr "" #: ../../exercises/network.rst:367 msgid "4 via B" msgstr "" #: ../../exercises/network.rst:367 msgid "1 via E" msgstr "" #: ../../exercises/network.rst:370 msgid "" "Distance vector protocols can operate in two different modes : `periodic " "updates` and `triggered updates`. `Periodic updates` is the default mode " "for a distance vector protocol. For example, each router could advertise " "its distance vector every thirty seconds. With the `triggered updates` a " "router sends its distance vector when its routing table changes (and " "periodically when there are no changes)." msgstr "" #: ../../exercises/network.rst:372 msgid "" "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 ?" msgstr "" #: ../../exercises/network.rst:374 msgid "" "Consider the same distance vector protocol, but now with `triggered " "updates`. When link `B-C` fails, assume that `B` updates its routing " "table immediately and sends its distance vector to `A` and `D`. Assume " "that both `A` and `D` process the received distance vector and that `A` " "sends its own distance vector, ... Indicate all the distance vectors that" " are exchanged and update the table above each time a distance vector is " "sent by a router (and received by other routers) until all routers have " "learned a new route to each destination. How many distance vector " "messages must be exchanged until the network converges to a stable state " "?" msgstr "" #: ../../exercises/network.rst:376 msgid "" "Consider again the network shown above. After some time, link state " "routing converges and all routers compute the same routing tables as " "above." msgstr "" #: ../../exercises/network.rst:378 msgid "" "An important difference between OSPF and RIP is that OSPF routers flood " "link state packets that allow the other routers to recompute their own " "routing tables while RIP routers exchange distance vectors. Consider that" " link `B-C` fails and that router `B` is the first to detect the failure." " At this point, `B` cannot reach anymore `C`, `D` and `E`. `C` cannot " "reach `B` and `A` anymore." msgstr "" #: ../../exercises/network.rst:380 msgid "" "Router `B` will flood its updated link state packet through the entire " "network and all routers will recompute their forwarding table. Upon " "reception of a link state packet, routers usually first flood the " "received link-state packet and then recompute their forwarding table. " "Assume that `B` is the first to recompute its forwarding table, followed " "by `D`, `A`, `C` and finally `E`." msgstr "" #: ../../exercises/network.rst:382 msgid "" "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." msgstr ""