-
Notifications
You must be signed in to change notification settings - Fork 1
/
mod1-07-p2.html
443 lines (399 loc) · 23.9 KB
/
mod1-07-p2.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Advanced Networking - Module 1 Chapter 7, Part 2 - IPv6 Addressing</title>
<meta name="description" content="Abilitante alle certificazioni Cisco CCENT e CCNA">
<meta name="author" content="Hacklab Cosenza">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
<link rel="stylesheet" href="css/reveal.css">
<link rel="stylesheet" href="css/theme/hlcs.css" id="theme">
<!-- Code syntax highlighting -->
<link rel="stylesheet" href="lib/css/zenburn.css">
<!-- Printing and PDF exports -->
<script>
var link = document.createElement( 'link' );
var link = document.createElement( 'link' );
link.rel = 'stylesheet';
link.type = 'text/css';
link.href = window.location.search.match( /print-pdf/gi ) ? 'css/print/pdf.css' : 'css/print/paper.css';
document.getElementsByTagName( 'head' )[0].appendChild( link );
</script>
<!--[if lt IE 9]>
<script src="lib/js/html5shiv.js"></script>
<![endif]-->
</head>
<body>
<div class="reveal">
<!-- Any section element inside of this container is displayed as a slide -->
<div class="slides">
<section>
<h1>Advanced Networking</h1>
<h2>Routing & Switching:</h2>
<h2>Introduction to Networks</h2>
<h3>Chapter 7, Part 2: IPv6 Addressing</h3>
<small><a href="http://hlcs.it">Hacklab Cosenza</a> / Centro di Ricerca su Tecnologia e Innovazione</small>
</section>
<section>
<section>
<h2>Transition to IPv6</h2>
<p>An upgrade from IPv4 was badly needed for several reasons (address space exhaustion, performances, extendibility).</p>
<p>This upgrade is <strong>IPv6</strong> and has been in the works since 1993 and has been ready for several years.</p>
<p>However the transition from IPv4 to IPv6 will be slow and take years, so for a long time <strong>the two protocols will coexist</strong>, thanks to several <strong>transition mechanisms</strong>:</p>
<ul>
<li><strong>Dual Stack</strong>: every host on the network runs both IPv4/6.</li>
<li><strong>Tunneling</strong>: IPv6 packets encapsulated inside IPv4 packets.</li>
<li><strong>Translation</strong>: NAT64 translates IPv4 packets into IPv6 packets, and viceversa.</li>
</ul>
</section>
<section>
<h2>[E] Transition to IPv6: Dual Stack</h2>
<img src="https://i.imgur.com/k3f0jsb.jpg">
<ul>
<li>If (an) <u>entire route between two networks</u> runs <strong>both IPv4/IPv6</strong>, their hosts can use IPv6-only between them.</li>
<li>For two networks, <strong>IPv6 routing could use different routes than IPv4</strong> routing.</li>
<li>IPv6 is growing, but <strong>only a fraction of the Internet is running on IPv6</strong>.</li>
<li>As of now, even if the entire path is dual stack, often <strong>IPv4 has priority</strong> (it's just easier this way).</li>
</ul>
</section>
<section>
<h2>[E] Transition to IPv6: Tunneling</h2>
<img src="https://i.imgur.com/GhiQBhC.jpg">
<ul>
<li>To traverse an IPv4-only network, a tunnel is created that <strong>makes it transparent to dual-stack hosts</strong>.</li>
<li>It's an IP-IP tunnel, precisely an <em>IPv6-in-IPv4</em> tunnel.</li>
<li><u>IPv6 packets are encapsulated inside IPv4 packets</u>, which are able to traverse the IPv4-only networks.</li>
<li>At the end of the tunnel, the (de-encapsulated) IPv6 layer 3 takes the place of the IPv4 L3.</li>
</ul>
</section>
<section>
<h2>[E] Transition to IPv6: NAT64</h2>
<img src="https://i.imgur.com/cMLFJfE.jpg">
<ul>
<li>If IPv4 hosts need <strong>to traverse IPv6-only networks</strong>, an <em>IPv4-in-IPv6</em> tunnel is definitely a possibility.</li>
<li>However, IPv6 has an explicit <strong>translation capability</strong> that can be used for this purpose: <strong>NAT64</strong> translates IPv4 addresses into corresponding IPv6 addresses.</li>
<li>Notice that <u>NAT64 is not about preserving addresses</u>, as it's the case with NAT for IPv4.</li>
</ul>
</section>
</section>
<section>
<section>
<h2>IPv6 Address Format</h2>
<img src="http://i.imgur.com/2Xf426J.gif" style="width: 600px;">
<p>An IPv6 address is <strong>128 bits long</strong>. It's not expressed with 16 decimal values, but instead <strong>32 hexadecimal digits</strong> are used. Example: 2607:f0d0:1002:0051:0000:0000:0000:0004.</p>
<p>Each group of 16 bits/4 hex digits (unofficially called an <em>hextet</em>) is <strong>separated by a colon</strong> (<code>:</code>) instead of a dot (<code>.</code>).</p>
<p>It's made of a <strong>Network Prefix</strong> (network part) and <strong>Interface ID</strong> (host part).</p>
</section>
<section>
<h2>IPv6 Preferred Format</h2>
<img src="http://i.imgur.com/2Xf426J.gif" style="width: 700px;">
<p>When we use all 32 hex digits to write an IPv6 address, we are using the <strong><em>preferred format</em></strong>.</p>
<p>It's not always ideal to use this many digits :(</p>
<p>But! There are rules to <strong>simplify the format</strong> than can be used often (but now always).</p>
</section>
<section>
<h2>Simplifying IPv6 Address Format</h2>
<h3>Rule 1: Omitting Leading 0s</h3>
<p>Any <strong>leading</strong> 0s in any of the hextets can be stripped out.</p>
<pre>Preferred - 2001:0DB8:0000:1110:0000:0000:0000:0230
No Lead 0 - 2001:DB8:0:1110:0:0:0:230
Preferred - 2001:0DB8:0000:A300:ABCD:0000:0000:1234
No Lead 0 - 2001:DB8:0:A300:ABCD:0:1234
Preferred - FE80:0000:0000:0000:0123:4567:89AB:CDEF
No Lead 0 - FE80:0:0:0:123:4567:89AB:CDEF
Preferred - FF02:0000:0000:0000:0000:0000:0000:0001
No Lead 0 - FF02:0:0:0:0:0:0:1
Preferred - 0000:0000:0000:0000:0000:0000:0000:0001
No Lead 0 - 0:0:0:0:0:0:0:1</pre>
<p>You <u>must not</u> strip the <strong>trailing</strong> 0s.</p>
</section>
<section>
<h2>Simplifying IPv6 Address Format</h2>
<h3>Rule 2: Omitting All-0s</h3>
<p>Any <strong>contiguos</strong> string of one or more hextets that consists of <strong>all-0s</strong> can be replaced by a <u>single</u> double colon (<code>::</code>).</p>
<pre><code class="no-highlight">YOU CAN ONLY USE THE :: _ONCE_ IN A IPv6 ADDRES!!!
Preferred - 2001:0DB8:0000:0000:1110:0000:0000:0230
No Lead 0 - 2001:DB8:0:0:1110:0:0:230
Compressed - 2001:DB8::1110:0:0:230 or 2001:DB8:0:0:1110::230
Preferred - 2001:0DB8:0000:A300:ABCD:0000:0000:1234
No Lead 0 - 2001:DB8:0:A300:ABCD:0:0:1234
Compressed - 2001:DB8::A300:ABCD:0:0:1234 or 2001:DB8:0:A300:ABCD::1234
Preferred - FE80:0000:0000:0000:0123:4567:89AB:CDEF
No Lead 0 - FE80:0:0:0:123:4567:89AB:CDEF
Compressed - FE80::123:4567:89AB:CDEF
Preferred - FF02:0000:0000:0000:0000:0000:0000:0001
No Lead 0 - FF02:0:0:0:0:0:0:1
Compressed - FF02::1
Preferred - 0000:0000:0000:0000:0000:0000:0000:0001
No Lead 0 - 0:0:0:0:0:0:0:1
Compressed - ::1</code></pre>
</section>
</section>
<section>
<h2>IPv6 Addresses</h2>
<p>In IPv6 too there are <strong>unicast</strong> and <strong>multicast</strong> addresses. It also has <strong>anycast</strong> addresses, which are <strong>assignable to multiple hosts</strong> and <strong>routed to the nearest</strong> one.</p>
<p><strong>IPv6 has no broadcast addresses</strong>. It achieves the same effect with a particular multicast address called <em>all-nodes</em>.</p>
<p>IPv6 doesn't use dotted notation for subnet masks. Instead <strong>it uses prefix lengths/slash notation ranging from 0 to 128</strong>.</p>
<p>A typical network prefix for IPv6 networks is /64:</p>
<img src="http://i.imgur.com/I2rCANR.gif">
</section>
<section>
<section>
<h2>IPv6 Unicast Addresses</h2>
<p>As in IPv4, in IPv6 transmissions the <strong>source address must be an unicast address</strong> that uniquely identifies that interface.</p>
<p>There are 6 types of IPv6 unicast addresses:</p>
<ul>
<li><strong>Global Unicast</strong>: Similar to <u>public</u> IPv4 Internet addresses, globally unique and routable.</li>
<li><strong>Link-Local</strong>: Used only for tranmission to other IPv6 hosts on the same link (subnet). They only must be unique in a single link, because <u>IPv6 router will never forward packets with link-local addresses</u>. Their range is <code>FE80::/10</code> - <code>FEBF::/10</code></li>
<li><strong>Loopback</strong>: The IPv6 loopback address is <code>::1/128</code> or <code>::1</code>.</li>
</ul>
</section>
<section>
<h2>IPv6 Unicast Addresses</h2>
<ul>
<li><strong>Unspecified</strong>: It's the <u>all-0s address</u>, <code>::/128</code> or <code>::</code>. It can't be assigned, and only used as source address by hosts yet to have IPv6 configured or when the source is irrelevant.</li>
<li><strong>Unique Local (ULA)</strong>: They are the <u>IPv6 counterpart of RFC 1918 Private Addresses</u>. ULAs are available for use in private networks, inside a single site or organization or spanning a limited number of sites. They are not routable in the global IPv6 Internet. The allocated block for ULAs is <code>fc00::/7</code> - <code>fdff::/7</code></li>
<li><strong>IPv4 Embedded</strong>: a particular type of address to help the transition from IPv4 to IPv6. They are, in fact, <u>IPv6 addresses that contain an IPv4 address</u> in the last 4 bytes.</li>
</ul>
</section>
</section>
<section>
<h2>IPv6 Link-Local Communications</h2>
<img src="http://i.imgur.com/3QmNjli.png">
<p>IPv6 <strong>supports multiple IPv6 addresses</strong> on an interface, and <u>at least one of them</u> <strong>must be a link-local address</strong>.</p>
<p>If it is not configured statically, it will be calculated automatically by the host without the need for DHCP.</p>
<p>It will be used to communicate <strong>with other IPv6 hosts on the same link/subnet</strong>, <u>including the default gw</u>.</p>
</section>
<section>
<section>
<h2>IPv6 Global Unicast Address</h2>
<img src="http://i.imgur.com/LGVfYS4.png">
<p>These are the <strong>IPv6 Internet-routable addresses</strong>, assigned by the IANA to the RIRs and then to the users. As of now, only addresses starting with <code>2000::/3</code> (first 3 bits 001) are being assigned.</p>
</section>
<section>
<h2>IPv6 Global Unicast Address</h2>
<p>A global unicast address is made of 3 components:</p>
<ul>
<li><strong>Global Routing Prefix</strong>: Currently RIR assigns IPv6 blocks with a /48 routing prefix.</li>
<li><strong>Subnet ID</strong>: A field available for assignees of a GRP block to define their subnets/sites.</li>
<ul>
<li>GRP + Subnet ID must be 64 bits.</li>
<li>This makes <strong>/64 the most used subnet mask</strong> for IPv6 users.</li>
</ul>
<li><strong>Interface ID</strong>: Equivalent to the host portion of IPv4. It's called a generic "ID" because IPv6 can have multiple global addresses on multiple interfaces.</li>
<ul>
<li>It is strongly recommended never to use an Interface ID smaller than 64 bits.</li>
</ul>
</ul>
</section>
<section>
<h2>IPv6 Global Unicast Address</h2>
<p>Unlike IPv4, in IPv6 it is possible to assign to hosts:</p>
<ul>
<li><strong>All-1s addresses</strong>, because IPv6 has no broadcast address.</li>
<li><strong>All-0s addresses</strong>, but they are reserved as anycast Subnet-routers address (the routers residing in a subnet).</li>
</ul>
</section>
</section>
<section>
<h2>Configure Static IPv6 Global Address</h2>
<p>Static configuration on <strong>Cisco routers</strong> is almost identical to IPv4, except the command is <code>ipv6 {address/prefix}</code>.</p>
<pre><code class="bash">R1(config)# interface gigabitethernet 0/0
R1(config-if)# ipv6 address 2001:db8:acad:1::1/64
R1(config-if)# no shutdown
R1(config-if)# exit</code></pre>
<p><strong>On a host</strong> the configuration is identical to IPv4, except it uses IPv6 addresses and prefixes. Optionally, the <strong>default gateway can be configured with its link-local address</strong>.</p>
<p>For automatic configuration of IPv6 addresses, there are two different ways: <strong>SLAAC and DHCPv6</strong>.</p>
</section>
<section>
<section>
<h2>Stateless Address Autoconfiguration</h2>
<p>Hosts using <strong>SLAAC</strong> rely on special, periodic messages from local IPv6 Routers called <em>ICMPv6 Router Advertisement (RA)</em>.</p>
<p>Hosts don't have to wait for a RA, but <strong>they can send a <em>Router Solicitation (RS)</em> message</strong> to local router(s).</p>
<p>RA contains everything hosts need: <strong>prefix, prefix length, default gateway</strong>. But also one of 3 possible responses:</p>
</section>
<section>
<h2>Stateless Address Autoconfiguration</h2>
<ul>
<li><strong>SLAAC only</strong> (Option 1, <u>default</u>): <em>Don't count on a DHCPv6 server</em>.</li>
<li><strong>SLAAC + DHCPv6</strong> (Option 2): <em>Other infos available from a DHCPv6 Server</em>.</li>
<li><strong>DHCPv6 only</strong> (Option 3): <em>Please rely exclusively on the DHCPv6 Server</em>.</li>
</ul>
<p>RA messages, and the default gateway information they contain, use the <strong>link-local IPv6 address</strong> of the router.</p>
</section>
<section>
<h2>DHCPv6</h2>
<p>The DHCP for IPv6 can provide hosts with <strong>a global unicast address, prefix length, default gateway and DNS servers</strong>.</p>
<p>An host can use <strong>none, some, or all</strong> theses informations, depending on the option specified in RAs:</p>
<ul>
<li>With <strong>Option 1</strong>, SLAAC only, a DHCPv6 server is absent.</li>
<li>With <strong>Option 2</strong>, SLAAC+DHCPv6, DHCPv6 operates in <strong>stateless mode</strong>: it just provides DNS servers and doesn't keep track of allocated IPv6 addresses.</li>
<li>With <strong>Option 3</strong>, DHCPv6 only, it behaves in the same <strong>stateful mode</strong> DHCPv4 does, keeping track of allocated resources.</li>
</ul>
</section>
<section>
<h2>IPv6 Address Generation</h2>
<ul>
<li>With DHCPv6-only, the server will provide <strong>the entire IPv6 address</strong> to the clients.</li>
<li>With SLAAC, <strong>the client must generate its own 64-bit interface ID</strong>.</li>
<ul>
<li>With the <em>Extended Unique Identifier</em> process, an host can calculate the <em>Interface ID</em> <strong>based on its own MAC address</strong>.</li>
<li>An host can also <strong>randomly calculate</strong> the Interface ID. This can mitigate privacy concerns in leaking one's own MAC address.</li>
</ul>
</ul>
</section>
<section>
<h2>EUI-64</h2>
<img src="http://i.imgur.com/08FYCF9.png" style="width: 850px;">
</section>
</section>
<section>
<section>
<h2>Link-Local Addresses Generation</h2>
<p>The link-local addresses can be <strong>dynamically generated</strong> by appending the Interface ID to the FE80::/64 network prefix.</p>
<p>Example: <code>fe80:0000:0000:0000:ea11:32ff:fe4e:486b</code>.</p>
<p>But because a MAC rarely contains many 0s, <strong>the resulting link-local address will be very long</strong> and uncompressable.</p>
<p>By <strong>statically</strong> providing link-local addresses we can make them way more easier to read. On Cisco routers:</p>
<pre><code class="bash">Router(config-if)# ipv6 address [link-local-address] link-local </code></pre>
</section>
<section>
<h2>Link-Local Addresses Generation</h2>
<p>Because they must be unique only over the same link, <strong>we can use the same link-local address on all the router interfaces</strong>:</p>
<pre><code class="bash">Router(config)#interface g0/0
Router(config-if)# ipv6 address fe80::1 link-local
Router(config-if)# exit
Router(config)#interface g0/1
Router(config-if)# ipv6 address fe80::1 link-local
Router(config-if)# exit
Router(config)#interface s0/0/0
Router(config-if)# ipv6 address fe80::1 link-local
Router(config-if)# exit</code></pre>
</section>
</section>
<section>
<section>
<h2>IPv6 Multicast Addresses</h2>
<p>As with IPv4, <strong>multicast groups are represented by addresses</strong>. There are 2 types of IPv6 multicast addresses:</p>
<ul>
<li><strong>Assigned</strong> - Reserved multicast addresses for pre-defined group on devices, or devices running a common protocol or known service. 2 common assigned multicasts are:</li>
<ul>
<li><strong>FF02::1 <em>All-Nodes Multicast Group</em></strong> - A multicast group that any IPv6-enabled host joins, effectively making it the "broadcast" address of IPv6.</li>
<li><strong>FF02::2 <em>All-Routers Multicast Group</em></strong> - A group joined by all IPv6 routers on the link/network.</li>
</ul>
</ul>
</section>
<section>
<h2>IPv6 Multicast Addresses</h2>
<ul>
<li><strong>Solicited Node</strong> - A multicast address created for each IPv6 interface, and consisting of a FF02::1:FF00:0:/104 prefix plus the <strong>least significant 24 bits of the Interface ID</strong> from the unicast address.</li>
<ul>
<li><strong><u>Important</u></strong>: the "00" in the FF00 is not part of the prefix.</li>
<li>They are used for obtaining the L2 addresses of other nodes with the <em>IPv6 Neighbor Discovery Protocol</em> (equivalent to IPv4's ARP).</li>
</ul>
</ul>
</section>
</section>
<section>
<h2>IPv6 Routers</h2>
<p>Being IPv6-enabled is not enough to be considered an IPv6 router. The <strong>basic features of an IPv6 router</strong> are:
<ul>
<li><strong>Forwarding IPv6 packets</strong> between different networks.</li>
<li>Ability to configure <strong>static IPv6 routes</strong> or a <strong>dynamic IPv6 routing protocol</strong>.</li>
<li><strong>Sending ICMPv6 Router Advertisement</strong> messages.</li>
</ul>
<p><u>IPv6 routing is not enabled by default on Cisco routers</u>: you need to enable it with <code>ipv6 unicast-routing</code>.</p>
<p>Link-local addresses are assigned to interfaces only after this <u>global config</u> command is executed.</p>
</section>
<section>
<section>
<h2>ICMP v4/v6</h2>
<p>The <strong>ICMP v4/v6</strong> (<em>Internet Control Protocol Message</em>) protocols are part of the TCP/IP protocol suite and <strong>provide feedback about certain errors involving IPv4/v6 packet processing</strong>.</p>
<p>Because of the information they provide, ICMP messages are frequently blocked for security.</p>
</section>
<section>
<h2>ICMP v4/v6</h2>
<p>These ICMP messages are common between v4 and v6:</p>
<ul>
<li><strong>Host Confirmation</strong>: an ICMP <em>Echo Request</em> is sent to <u>test if an host in operational</u>. If it is an <em>Echo Reply</em> is sent back.</li>
<ul>
<li>ICMP Echo messagges are fundamental to the <code>ping</code> network verification utility.</li>
</ul>
<li><strong>Destination or Service Unreachable</strong>: when a <u>gateway can't forward a packet</u>, it notifies the source with a code specifying if the net, host, protocol or port is unreachable.</li>
<li><strong>Time Exceeded</strong>: Used to notify the packet source that the <u>TTL counter in the header has reached 0</u> and the packet is being dropped.</li>
</ul>
</section>
<section>
<h2>ICMP v6</h2>
<p>ICMPv6 introduced 4 new messages as part of the <strong>Neighbour Discovery Protocol (NDP)</strong>:
<ul>
<li><strong>Router Solicitation (RS)</strong> - Sent by hosts to routers to <u>obtain addressing</u> autoconfiguration information.</li>
<li><strong>Router Advertisement (RA)</strong> - Sent by router to hosts to <u>provide addressing</u> autoconfiguration information.</li>
<li><strong>Neighbor Solicitation (NS)</strong> -Sent by an host to another host to <u>discover its L2 address</u> or to <u>detect a duplicate address</u>.</li>
<li><strong>Neighbor Advertisement (NA)</strong> - <u>Sent by an host who received a NS</u> to comunicate its L2 address or that an IPv6 address is already in use.</li>
</ul>
</section>
</section>
<section>
<h2>Ping</h2>
<p>The <code>ping</code> testing utility uses <strong>ICMP Echo request/reply messages to test connectivity between hosts</strong>. There is a <em>timeout</em> and ping considers replies received within it as successful "pings".</p>
<p>It reports the success rate and the time it took between request and reply, important <u>measures of network performances</u>.</p>
<p>A successful ping means correct connectivity, but an unsuccessful one does not necessarily imply connectivity issues:</p>
<ul>
<li>The target host could be not operational.</li>
<li>ICMP messages could be blocked for security reasons.</li>
</ul>
</section>
<section>
<section>
<h2>Traceroute</h2>
<p>While ping just test connectivity between 2 hosts, <code>traceroute</code> (<code>tracert</code> in Windows) <strong>details the path</strong> taken by the packet.</p>
<p><code>traceroute</code> provides its functions by <strong>exploiting the ICMP time exceeded messages caused by deliberately low TTL values</strong>.</p>
<p><strong>Each row in its output is the interface of a router (hop)</strong> the packet traversed. An asterisk (*) means a <strong>lost packet</strong>. Times represent the <strong>Round Trip Time (RTT)</strong> between sending the packet and getting the response. </p>
<p>Traceroutes can help identify <u>where in the path a problem occurs</u>.</p>
</section>
<section>
<h2>Traceroute</h2>
<pre><code class="no-highlight">stefanauss@barney:~$ traceroute -n google.it
traceroute to google.it (173.194.40.15), 30 hops max, 60 byte packets
1 10.87.23.1 0.257 ms 0.284 ms 0.346 ms
2 * * *
3 172.18.1.129 25.915 ms 28.067 ms 30.293 ms
4 172.18.0.77 31.994 ms 40.412 ms 172.18.0.73 36.516 ms
5 172.19.240.173 56.398 ms 58.932 ms 58.996 ms
6 195.22.192.85 59.228 ms 63.312 ms 66.776 ms
7 74.125.51.12 62.567 ms 72.14.196.141 41.077 ms 40.297 ms
8 209.85.249.54 40.273 ms 40.186 ms 40.549 ms
9 64.233.174.245 40.962 ms 40.498 ms 39.815 ms
10 173.194.40.15 43.655 ms 43.748 ms 40.498 ms</code></pre>
</section>
</section>
<section>
<h1>End of Lesson</h1>
</section>
</div>
</div>
<script src="lib/js/head.min.js"></script>
<script src="js/reveal.js"></script>
<script>
// More info https://github.com/hakimel/reveal.js#configuration
Reveal.initialize({
controls: true,
progress: true,
history: true,
center: true,
transition: 'slide', // none/fade/slide/convex/concave/zoom
// More info https://github.com/hakimel/reveal.js#dependencies
dependencies: [
{ src: 'lib/js/classList.js', condition: function() { return !document.body.classList; } },
{ src: 'plugin/markdown/marked.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },
{ src: 'plugin/markdown/markdown.js', condition: function() { return !!document.querySelector( '[data-markdown]' ); } },
{ src: 'plugin/highlight/highlight.js', async: true, callback: function() { hljs.initHighlightingOnLoad(); } },
{ src: 'plugin/zoom-js/zoom.js', async: true },
{ src: 'plugin/notes/notes.js', async: true }
]
});
</script>
</body>
</html>