WEBVTT

1
00:00:00.080 --> 00:00:03.839
<v Speaker 1>Ever felt like you're caught in the intricate digital currents

2
00:00:03.879 --> 00:00:06.000
<v Speaker 1>of the Internet, maybe wishing you had a map to

3
00:00:06.080 --> 00:00:10.119
<v Speaker 1>understand what truly makes it tick. Well, today we're diving deep.

4
00:00:10.439 --> 00:00:13.720
<v Speaker 1>We're going into the foundational concepts of Cisco networking, kind

5
00:00:13.720 --> 00:00:15.720
<v Speaker 1>of pulling back the curtain on the magic that connects

6
00:00:15.720 --> 00:00:19.199
<v Speaker 1>our digital world. Our guide for this journey is Understanding

7
00:00:19.239 --> 00:00:23.480
<v Speaker 1>Cisco Networking Technologies by Todd Lammle. It's a real gold

8
00:00:23.519 --> 00:00:25.359
<v Speaker 1>mine of practical insights.

9
00:00:25.000 --> 00:00:29.079
<v Speaker 2>Absolutely, and our mission here is well pretty precise to

10
00:00:29.079 --> 00:00:33.159
<v Speaker 2>give you a clear, concise and hopefully genuinely engaging understanding

11
00:00:33.159 --> 00:00:35.560
<v Speaker 2>of how these systems work. You know, from the smallest

12
00:00:35.560 --> 00:00:39.000
<v Speaker 2>home setup all the way up to the largest enterprise network.

13
00:00:39.280 --> 00:00:42.079
<v Speaker 2>Think of this as your personalized shortcut maybe to being

14
00:00:42.079 --> 00:00:44.280
<v Speaker 2>well informed about the whole internetworking universe.

15
00:00:44.520 --> 00:00:48.000
<v Speaker 1>Yeah, we'll explore everything from like how a simple file

16
00:00:48.079 --> 00:00:52.159
<v Speaker 1>moves across your local network to the really complex systems

17
00:00:52.200 --> 00:00:56.159
<v Speaker 1>that route data across continents. This deep dive is designed

18
00:00:56.200 --> 00:00:58.840
<v Speaker 1>to arm you with a robust understanding, and yeah, we're

19
00:00:58.880 --> 00:01:01.960
<v Speaker 1>definitely aiming for more than in a few aha moments

20
00:01:02.000 --> 00:01:05.640
<v Speaker 1>along the way. So let's jump in. Let's begin with

21
00:01:05.640 --> 00:01:08.680
<v Speaker 1>a scenario from our source material that perfectly illustrates the

22
00:01:08.719 --> 00:01:12.400
<v Speaker 1>problem networks we're well designed to solve. Imagine a tread

23
00:01:12.439 --> 00:01:15.879
<v Speaker 1>called chaos court. Right, Bob wants to tell Sally something

24
00:01:16.359 --> 00:01:19.200
<v Speaker 1>on very basic hub based network. Bob just shouts her

25
00:01:19.239 --> 00:01:21.000
<v Speaker 1>name and everyone hears it. Hey, everyone, I need to

26
00:01:21.000 --> 00:01:23.920
<v Speaker 1>talk to Sally. Yeah, the hub it just blindly repeats

27
00:01:23.959 --> 00:01:27.519
<v Speaker 1>every signal to every connected device. Yeah, it's just noise exactly.

28
00:01:27.840 --> 00:01:31.760
<v Speaker 1>This means a single collision domain where conversations, you know, clash,

29
00:01:31.879 --> 00:01:34.359
<v Speaker 1>and a single broadcast domain where everyone hears every word.

30
00:01:34.920 --> 00:01:38.079
<v Speaker 2>Not exactly efficient, is it, No, It's an instant recipe

31
00:01:38.079 --> 00:01:41.680
<v Speaker 2>for noise and slow downs. What's fascinating here, though, is

32
00:01:41.719 --> 00:01:45.920
<v Speaker 2>how quickly networks evolved beyond this chaos court thing. The

33
00:01:46.000 --> 00:01:50.680
<v Speaker 2>moment you introduce a switch, you dramatically improve efficiency. Switches

34
00:01:50.760 --> 00:01:53.599
<v Speaker 2>operate at layer two that's the data link layer, and

35
00:01:53.680 --> 00:01:56.319
<v Speaker 2>they're intelligent. They break up collision domains.

36
00:01:56.480 --> 00:01:57.680
<v Speaker 1>Okay, so how does that work?

37
00:01:57.840 --> 00:02:01.000
<v Speaker 2>Well, each port on a switch becomes its own collision domain.

38
00:02:01.480 --> 00:02:05.239
<v Speaker 2>That means devices can communicate much more smoothly without constantly

39
00:02:05.280 --> 00:02:07.680
<v Speaker 2>bumping into each other's signals. It's like giving everyone a

40
00:02:07.719 --> 00:02:09.759
<v Speaker 2>separate direct line to the switch.

41
00:02:09.560 --> 00:02:13.960
<v Speaker 1>Right, So switches handle collisions. But even with switches, I

42
00:02:14.000 --> 00:02:16.400
<v Speaker 1>think you said, every device can still be in the

43
00:02:16.439 --> 00:02:21.039
<v Speaker 1>same broadcast domain, meaning everyone still hears those general shouts.

44
00:02:21.599 --> 00:02:23.240
<v Speaker 1>Mean for anyone else on that segment.

45
00:02:23.319 --> 00:02:26.319
<v Speaker 2>That's exactly right. And this is where routers truly transform

46
00:02:26.400 --> 00:02:29.919
<v Speaker 2>network design. Routers, working at layer three, the network layer,

47
00:02:30.000 --> 00:02:33.479
<v Speaker 2>through the sophisticated traffic cops, they break up broadcast domains

48
00:02:33.479 --> 00:02:36.759
<v Speaker 2>by default. That's huge. It ensures general announcements only go

49
00:02:36.840 --> 00:02:37.879
<v Speaker 2>where they're actually needed.

50
00:02:38.000 --> 00:02:40.759
<v Speaker 1>Ah, so it prevents that network wide noise and improves

51
00:02:40.800 --> 00:02:41.960
<v Speaker 1>performance significantly.

52
00:02:42.039 --> 00:02:45.080
<v Speaker 2>Precisely, and if we connect this to the bigger picture,

53
00:02:45.439 --> 00:02:50.159
<v Speaker 2>keeping broadcast domains small is just crucial for scalable, efficient networks.

54
00:02:50.599 --> 00:02:54.400
<v Speaker 2>Large ones they just flood users with unnecessary traffic, eat

55
00:02:54.479 --> 00:02:57.840
<v Speaker 2>up bandwidth and slow down response times. Routers don't just

56
00:02:57.960 --> 00:03:02.240
<v Speaker 2>segment networks. They intelligently filter traffic based on IP addresses,

57
00:03:02.360 --> 00:03:06.080
<v Speaker 2>They perform packet switching, and they make best path selections

58
00:03:06.159 --> 00:03:09.360
<v Speaker 2>using routing tables. They effectively turn all these separate local

59
00:03:09.400 --> 00:03:13.080
<v Speaker 2>networks into a harmonious inter network. Our source even calls

60
00:03:13.120 --> 00:03:16.240
<v Speaker 2>them totally obsessive when it comes to networks, which honestly

61
00:03:16.360 --> 00:03:19.159
<v Speaker 2>is exactly what you want for keeping things orderly makes sense.

62
00:03:19.960 --> 00:03:23.639
<v Speaker 1>Beyond these core devices routers and switches, our networks also

63
00:03:23.719 --> 00:03:27.599
<v Speaker 1>use wireless land or w land devices, things like access

64
00:03:27.599 --> 00:03:30.680
<v Speaker 1>points APS. These are the bridges, right, allowing your wireless

65
00:03:30.680 --> 00:03:32.840
<v Speaker 1>devices to connect to the wired network, and they often

66
00:03:32.879 --> 00:03:34.879
<v Speaker 1>live in their own virtual lands of the lands.

67
00:03:34.879 --> 00:03:38.280
<v Speaker 2>For better organization and for managing, say a whole bunch

68
00:03:38.319 --> 00:03:41.240
<v Speaker 2>of aps, especially in a business setting, you have wland controllers.

69
00:03:41.520 --> 00:03:44.280
<v Speaker 2>Cisco's Maraki cloud system is a good example. They become

70
00:03:44.400 --> 00:03:48.199
<v Speaker 2>essential for administrators to oversee and secure their wireless infrastructure.

71
00:03:48.360 --> 00:03:52.479
<v Speaker 1>Okay, and just to round out these building blocks, every

72
00:03:52.520 --> 00:03:56.560
<v Speaker 1>network has both physical topology that's like how the cables

73
00:03:56.560 --> 00:03:59.080
<v Speaker 1>and devices are actually laid out, like the common star

74
00:03:59.159 --> 00:04:02.560
<v Speaker 1>layout with central switch. And then there's the logical topology,

75
00:04:02.759 --> 00:04:06.039
<v Speaker 1>which describes how the signal actually travels. For instance, Ethernet

76
00:04:06.080 --> 00:04:09.400
<v Speaker 1>often creates a logical bus even within that star physical layout.

77
00:04:09.800 --> 00:04:12.719
<v Speaker 1>Understanding both helps you visualize the data flow, right.

78
00:04:12.759 --> 00:04:15.319
<v Speaker 2>It's about the physical layout versus the actual path the

79
00:04:15.400 --> 00:04:16.079
<v Speaker 2>data takes.

80
00:04:16.319 --> 00:04:20.000
<v Speaker 1>So from the the noise of chaos court we quickly

81
00:04:20.040 --> 00:04:23.079
<v Speaker 1>see the need for a common language. Early networks were

82
00:04:23.120 --> 00:04:26.720
<v Speaker 1>like isolated islands, a decent system couldn't talk to an

83
00:04:26.759 --> 00:04:29.759
<v Speaker 1>IBM system, for example. The fundamental insight here is that

84
00:04:29.800 --> 00:04:32.720
<v Speaker 1>the Internet as we know it just couldn't exist without

85
00:04:32.759 --> 00:04:34.560
<v Speaker 1>standardized communication absolutely.

86
00:04:34.800 --> 00:04:37.720
<v Speaker 2>This led directly to the creation of the Open System's

87
00:04:37.759 --> 00:04:40.600
<v Speaker 2>Interconnection or OSI reference model that was back in the

88
00:04:40.680 --> 00:04:43.720
<v Speaker 2>late nineteen seventies by the ISO, the International Organization for

89
00:04:43.839 --> 00:04:47.879
<v Speaker 2>Standardization Right and the OSI model's primary purpose was well

90
00:04:48.000 --> 00:04:50.839
<v Speaker 2>groundbreaking at the time. It was to help vendors create

91
00:04:50.879 --> 00:04:55.279
<v Speaker 2>interoperable network devices and software. It lays out this seven

92
00:04:55.360 --> 00:04:58.680
<v Speaker 2>layer hierarchical approach. The power of this model is how

93
00:04:58.720 --> 00:05:03.279
<v Speaker 2>it divides complex network processes into simpler, manageable chunks. This

94
00:05:03.319 --> 00:05:06.279
<v Speaker 2>allows multiple vendors to develop devices that can all speak

95
00:05:06.319 --> 00:05:09.639
<v Speaker 2>the same language essentially, and it prevents a change in

96
00:05:09.680 --> 00:05:12.920
<v Speaker 2>one layer from messing up the entire stack. It really

97
00:05:12.920 --> 00:05:14.480
<v Speaker 2>paved the way, and each.

98
00:05:14.319 --> 00:05:18.879
<v Speaker 1>Of these seven layers, let's the application, presentation, session, transport,

99
00:05:19.040 --> 00:05:23.600
<v Speaker 1>network data, link and physical data gets progressively encapsulated like

100
00:05:23.639 --> 00:05:25.879
<v Speaker 1>putting a letter in an envelope, than that envelope.

101
00:05:25.560 --> 00:05:28.439
<v Speaker 2>In a package exactly like that. Each step adds necessary

102
00:05:28.480 --> 00:05:33.519
<v Speaker 2>control information, transforming your original data into segments than packets,

103
00:05:33.560 --> 00:05:35.560
<v Speaker 2>than frames, and finally just bits on the wire that

104
00:05:35.639 --> 00:05:37.160
<v Speaker 2>can actually travel across a cable.

105
00:05:37.439 --> 00:05:40.240
<v Speaker 1>So OSI is the big do print, But in practice

106
00:05:40.240 --> 00:05:43.199
<v Speaker 1>we often talk more about the TCPIP and DoD models,

107
00:05:43.600 --> 00:05:44.639
<v Speaker 1>which are more condensed.

108
00:05:44.959 --> 00:05:48.680
<v Speaker 2>Yeah, that's true, and the history there is fascinating. Tcpit's

109
00:05:48.759 --> 00:05:52.040
<v Speaker 2>roots are deep in arpenet, you know, the Internet's ancestor.

110
00:05:52.480 --> 00:05:55.240
<v Speaker 2>It came out of government research, sure, but a lot

111
00:05:55.279 --> 00:05:58.680
<v Speaker 2>of its development happened at UC Berkeley, bundled with BSD Unix,

112
00:05:59.160 --> 00:06:03.399
<v Speaker 2>and that became the robust, adaptable foundation for today's global Internet.

113
00:06:03.800 --> 00:06:06.439
<v Speaker 2>The d ID model, for instance, it distills these functions

114
00:06:06.480 --> 00:06:10.959
<v Speaker 2>into just four layers process, application, host to host or transport,

115
00:06:11.279 --> 00:06:13.519
<v Speaker 2>Internet and network access or link.

116
00:06:13.720 --> 00:06:16.959
<v Speaker 1>Okay, let's zoom in on some key TCP IP protocols

117
00:06:17.000 --> 00:06:19.519
<v Speaker 1>you probably interact with every single day. Starting at the

118
00:06:19.519 --> 00:06:21.680
<v Speaker 1>top of the process application layer. This is where your

119
00:06:21.680 --> 00:06:24.560
<v Speaker 1>applications talk to the network. So here we have DNS

120
00:06:24.800 --> 00:06:28.360
<v Speaker 1>Domain Name system right, translating human friendly domain names like www,

121
00:06:28.439 --> 00:06:31.560
<v Speaker 1>dot lambload dot com into the numerical IP addresses the

122
00:06:31.600 --> 00:06:35.920
<v Speaker 1>network understands. Then there's HGTP and its secure version HTTPS,

123
00:06:36.079 --> 00:06:39.040
<v Speaker 1>which basically powers all your web browsing. We also find

124
00:06:39.120 --> 00:06:42.720
<v Speaker 1>FTP for efficient file transfers and SMMP, which is crucial

125
00:06:42.959 --> 00:06:46.319
<v Speaker 1>for network management stations to monitor devices good list.

126
00:06:46.920 --> 00:06:49.920
<v Speaker 2>Moving down to the host to host or transport layer,

127
00:06:50.560 --> 00:06:53.199
<v Speaker 2>this is where we make really crucial decisions about how

128
00:06:53.240 --> 00:06:56.120
<v Speaker 2>reliable your data needs to travel, and we mainly distinguish

129
00:06:56.120 --> 00:07:00.720
<v Speaker 2>between TCP and UDP here. TCP that's transmission can protocol.

130
00:07:00.920 --> 00:07:03.399
<v Speaker 2>It's like sending a registered letter. It's reliable.

131
00:07:03.519 --> 00:07:06.560
<v Speaker 1>Connection oriented, uses that three way handchick right.

132
00:07:06.439 --> 00:07:11.240
<v Speaker 2>Exactly to establish communication. Then it uses sequencing, acknowledgments, and

133
00:07:11.279 --> 00:07:15.560
<v Speaker 2>flow control to guarantee delivery. Every single segment is accounted for.

134
00:07:16.240 --> 00:07:19.560
<v Speaker 1>That sounds incredibly robust, which makes me ask, why would

135
00:07:19.560 --> 00:07:22.120
<v Speaker 1>you ever not want all that reliability. I mean my

136
00:07:22.120 --> 00:07:25.120
<v Speaker 1>first thought is all that guaranteeing must add overhead, maybe

137
00:07:25.160 --> 00:07:26.120
<v Speaker 1>slow things down.

138
00:07:26.240 --> 00:07:31.519
<v Speaker 2>You're exactly right. TCP comes with significant network overhead sometimes,

139
00:07:31.560 --> 00:07:34.319
<v Speaker 2>believe it or not, Less reliable is more powerful. That's

140
00:07:34.360 --> 00:07:37.399
<v Speaker 2>where UDP comes in User datagram protocol. It's the scale

141
00:07:37.480 --> 00:07:40.879
<v Speaker 2>down economy model. As the source puts it, it's connectionless

142
00:07:40.920 --> 00:07:44.079
<v Speaker 2>and unreliable in the sense that it doesn't guarantee delivery

143
00:07:44.160 --> 00:07:47.120
<v Speaker 2>or order but this isn't a flaw, it's a feature.

144
00:07:47.480 --> 00:07:51.199
<v Speaker 2>It's a deliberate design choice that unlocks real time experiences.

145
00:07:51.720 --> 00:07:55.560
<v Speaker 2>It's incredibly fast and efficient with much less overhead, perfect

146
00:07:55.600 --> 00:07:58.639
<v Speaker 2>for things like video streaming or voiceover IP where a

147
00:07:58.720 --> 00:08:02.199
<v Speaker 2>dropped packet here or there is less critical than delay.

148
00:08:02.279 --> 00:08:05.160
<v Speaker 1>Makes sense well, speedover guaranteed delivery for something.

149
00:08:04.920 --> 00:08:08.360
<v Speaker 2>Right, and both TCP and UDP use port numbers to

150
00:08:08.439 --> 00:08:11.079
<v Speaker 2>keep track of different applications and conversations happening at the

151
00:08:11.079 --> 00:08:14.399
<v Speaker 2>same time, like specific apartment numbers in a large building, you.

152
00:08:14.360 --> 00:08:16.800
<v Speaker 1>Know, got it. And then at the Internet.

153
00:08:16.560 --> 00:08:20.240
<v Speaker 2>Layer here we have IP itself Internet protocol. This is

154
00:08:20.279 --> 00:08:23.959
<v Speaker 2>the core. It's aware of all interconnected networks, responsible for

155
00:08:24.000 --> 00:08:28.360
<v Speaker 2>that logical addressing and routing packets across vast distances supporting IP.

156
00:08:28.560 --> 00:08:32.279
<v Speaker 2>You've got ICMP Internet Control Message Protocol that's used for

157
00:08:32.320 --> 00:08:35.440
<v Speaker 2>diagnostics like the PIN command and for air reporting. And

158
00:08:35.480 --> 00:08:39.039
<v Speaker 2>then there's ARP Address Resolution Protocol. This does the essential

159
00:08:39.120 --> 00:08:42.279
<v Speaker 2>job of resolving those logical IP addresses to physical hardware

160
00:08:42.399 --> 00:08:45.879
<v Speaker 2>or MRC addresses, but only on the local network. It's

161
00:08:45.919 --> 00:08:48.600
<v Speaker 2>how your computer finds the physical address of its local

162
00:08:48.639 --> 00:08:49.519
<v Speaker 2>router for example.

163
00:08:49.639 --> 00:08:53.080
<v Speaker 1>Okay, now for the really practical site IP addressing. Every

164
00:08:53.080 --> 00:08:56.399
<v Speaker 1>device on an IP network gets a unique numeric identifier,

165
00:08:56.679 --> 00:08:59.639
<v Speaker 1>a software address. It's hierarchical, right, like a phone number,

166
00:08:59.720 --> 00:09:02.639
<v Speaker 1>area code, prefix, customer number. We write these thirty two

167
00:09:02.679 --> 00:09:05.080
<v Speaker 1>bits in four octets or bites, usually in that dot

168
00:09:05.159 --> 00:09:07.679
<v Speaker 1>decimal format like one seventy two point one three zero

169
00:09:07.679 --> 00:09:10.360
<v Speaker 1>point five to six. We categorize them into class A,

170
00:09:10.519 --> 00:09:13.240
<v Speaker 1>B and C addresses, each with a default subnet mask

171
00:09:13.360 --> 00:09:15.240
<v Speaker 1>like two five to five p on zero point zero

172
00:09:15.320 --> 00:09:17.399
<v Speaker 1>point zero four Class A. This mask tells you which

173
00:09:17.399 --> 00:09:18.759
<v Speaker 1>part is the network and which part is the.

174
00:09:18.679 --> 00:09:22.360
<v Speaker 2>Host exactly, and the power of that subnet mask really

175
00:09:22.360 --> 00:09:26.759
<v Speaker 2>comes alive with subnetting. Now, our source material playfully suggests

176
00:09:26.759 --> 00:09:29.080
<v Speaker 2>you'll actually be able to subnet a network in your head.

177
00:09:29.320 --> 00:09:32.639
<v Speaker 2>Maybe not instantly, but the key insight is that subnetting

178
00:09:32.679 --> 00:09:35.039
<v Speaker 2>is the art of borrowing bits from the host portion

179
00:09:35.080 --> 00:09:38.679
<v Speaker 2>of an IP address to create smaller, more manageable networks.

180
00:09:39.120 --> 00:09:43.519
<v Speaker 2>It's definitely challenging, but it's an indispensably crucial skill for

181
00:09:43.639 --> 00:09:47.240
<v Speaker 2>real world networking. It lets you use IP address space

182
00:09:47.279 --> 00:09:52.039
<v Speaker 2>efficiently and importantly keep those broadcast domains small. Helps prevent

183
00:09:52.080 --> 00:09:53.679
<v Speaker 2>another chaos court.

184
00:09:53.600 --> 00:09:57.440
<v Speaker 1>Right, efficiency and control and to conserve the limited supply

185
00:09:57.480 --> 00:09:59.840
<v Speaker 1>of public IPA addresses, and also for security, we use

186
00:09:59.840 --> 00:10:04.399
<v Speaker 1>p i at IP addresses right defined in RFC nineteen eighteen. Crucially,

187
00:10:04.480 --> 00:10:06.639
<v Speaker 1>these are not routable on the public Internet.

188
00:10:06.360 --> 00:10:09.240
<v Speaker 2>Correct, which means ISPs and corporations only need a small

189
00:10:09.240 --> 00:10:12.159
<v Speaker 2>block of public EPs to connect their entire internal private

190
00:10:12.200 --> 00:10:15.639
<v Speaker 2>network to the outside world. Saves valuable public address space

191
00:10:15.679 --> 00:10:18.279
<v Speaker 2>and adds a nice layer of security through obscurity.

192
00:10:18.399 --> 00:10:21.159
<v Speaker 1>Essentially okay, And we also distinguish between different types of

193
00:10:21.200 --> 00:10:22.480
<v Speaker 1>traffic patterns we do.

194
00:10:23.120 --> 00:10:27.279
<v Speaker 2>Unicast is just one to one conversation. Simple multicast is

195
00:10:27.320 --> 00:10:29.360
<v Speaker 2>one to many, like sending out a video stream to

196
00:10:29.399 --> 00:10:32.840
<v Speaker 2>a specific group of subscribers who've opted in, and broadcasts

197
00:10:32.840 --> 00:10:35.720
<v Speaker 2>are one to all within a specific domain. Layer two

198
00:10:35.720 --> 00:10:39.159
<v Speaker 2>broadcasts use that special MSc address all f's and hex

199
00:10:39.159 --> 00:10:42.039
<v Speaker 2>and they stay within a land. Routers will never forward them.

200
00:10:42.320 --> 00:10:46.960
<v Speaker 2>That reinforces their role in managing broadcast domains. Layer three broadcasts,

201
00:10:46.960 --> 00:10:49.000
<v Speaker 2>on the other hand, use an IP address with all

202
00:10:49.039 --> 00:10:51.240
<v Speaker 2>host bits turned on, and they reach all hosts within

203
00:10:51.320 --> 00:10:52.960
<v Speaker 2>that specific broadcast domain.

204
00:10:53.039 --> 00:10:54.879
<v Speaker 1>Got it. So, with those concepts down, let's turn to

205
00:10:54.919 --> 00:10:58.879
<v Speaker 1>the brain of Cisco devices, their operating system the Cisco

206
00:10:58.919 --> 00:11:02.279
<v Speaker 1>Internetwork operating System or iOS, and its command line interface,

207
00:11:02.320 --> 00:11:06.360
<v Speaker 1>the CLI. This is the kernel allocating resources managing tasks. Now,

208
00:11:06.360 --> 00:11:09.039
<v Speaker 1>setting up admin functions here doesn't magically make a device

209
00:11:09.080 --> 00:11:12.480
<v Speaker 1>work faster, but our source advises your life will be

210
00:11:12.480 --> 00:11:13.840
<v Speaker 1>a whole lot better if you do. Yeah.

211
00:11:13.879 --> 00:11:16.080
<v Speaker 2>Basic housekeeping makes a huge difference, right.

212
00:11:16.480 --> 00:11:19.879
<v Speaker 1>This includes setting host names, ideally mapping to a physical

213
00:11:19.879 --> 00:11:22.879
<v Speaker 1>location not you know, Todd's office router like in the

214
00:11:22.879 --> 00:11:26.799
<v Speaker 1>book example, adding banners for security notices like a message

215
00:11:26.840 --> 00:11:30.600
<v Speaker 1>of the day, and critically configuring secure passwords.

216
00:11:30.840 --> 00:11:34.399
<v Speaker 2>And when it comes to passwords, security is paramount. You

217
00:11:34.519 --> 00:11:37.679
<v Speaker 2>need to set an enable secret that encrypts the main

218
00:11:37.799 --> 00:11:42.360
<v Speaker 2>administrative password. Understand that the older enable password command it

219
00:11:42.440 --> 00:11:45.879
<v Speaker 2>leaves the password unencrypted by default in the CONFIGU big

220
00:11:45.919 --> 00:11:49.000
<v Speaker 2>no no. You also need to secure access for direct

221
00:11:49.000 --> 00:11:52.799
<v Speaker 2>console connections and for VTY virtual terminal access. That's how

222
00:11:52.799 --> 00:11:55.919
<v Speaker 2>you connect remotely using things like telnet or SSH.

223
00:11:56.039 --> 00:11:58.120
<v Speaker 1>And you mentioned telnet, right, It's.

224
00:11:58.080 --> 00:12:01.080
<v Speaker 2>Vital to remember telnet sends passwords and clear text. It's

225
00:12:01.080 --> 00:12:02.960
<v Speaker 2>a huge security risk. Just don't use it if you

226
00:12:02.960 --> 00:12:07.000
<v Speaker 2>can avoid it. Secure shell SSH is the modern secure alternative.

227
00:12:07.080 --> 00:12:09.399
<v Speaker 2>It requires setting up a host name, a domain name,

228
00:12:09.440 --> 00:12:12.600
<v Speaker 2>and generating cryptographic keys first, and for an added layer

229
00:12:12.600 --> 00:12:15.120
<v Speaker 2>of protection, you can encrypt all passwords, showing and the

230
00:12:15.200 --> 00:12:18.240
<v Speaker 2>running configuration with a single command service Password Encryption.

231
00:12:18.399 --> 00:12:21.960
<v Speaker 1>Good tip. Okay, Configuring interfaces is arguably the most vital

232
00:12:22.000 --> 00:12:25.320
<v Speaker 1>router configuration right getting it talking on the network, you

233
00:12:25.440 --> 00:12:29.240
<v Speaker 1>use the by address command to assign the IP and mask.

234
00:12:29.840 --> 00:12:33.000
<v Speaker 1>But remember you don't set an IP addressed directly on

235
00:12:33.080 --> 00:12:36.519
<v Speaker 1>layer two switchboard. That works differently. You enable an interface

236
00:12:36.840 --> 00:12:39.440
<v Speaker 1>with the no shutdown command, Otherwise it just sits there

237
00:12:39.480 --> 00:12:43.120
<v Speaker 1>doing nothing. And here's a handy CLI tip the dew command.

238
00:12:43.519 --> 00:12:45.720
<v Speaker 1>It lets you run show commands even when you're inside

239
00:12:45.720 --> 00:12:48.159
<v Speaker 1>configuration mode, which saves a ton of time jumping back

240
00:12:48.200 --> 00:12:48.519
<v Speaker 1>and forth.

241
00:12:48.559 --> 00:12:50.559
<v Speaker 2>Oh yeah, the dow umpaying is a lifesaver.

242
00:12:50.960 --> 00:12:54.120
<v Speaker 1>So to properly manage these Cisco devices, you also need

243
00:12:54.120 --> 00:12:57.879
<v Speaker 1>to understand their internal architecture, their memory types. RAM holds

244
00:12:57.919 --> 00:13:01.919
<v Speaker 1>the running configuration, the active setup ENVYRAM non voldel RAMS

245
00:13:01.960 --> 00:13:04.600
<v Speaker 1>stores the startup configuration, the one that loads on boot

246
00:13:04.639 --> 00:13:08.120
<v Speaker 1>it persists across reboots. Flash memory holds the Cisco iOS

247
00:13:08.159 --> 00:13:12.000
<v Speaker 1>image itself, the actual operating system file and RAM contains

248
00:13:12.000 --> 00:13:14.919
<v Speaker 1>a mini iOS like a basic bootloader. Crucially, there's the

249
00:13:14.960 --> 00:13:16.039
<v Speaker 1>configuration register.

250
00:13:16.279 --> 00:13:20.360
<v Speaker 2>Ah, yes, the config register. It's a powerful, low level setting.

251
00:13:20.720 --> 00:13:23.840
<v Speaker 2>It's a sixteen bit value that controls how the router boots.

252
00:13:24.240 --> 00:13:28.879
<v Speaker 2>It includes options for crucial password recovery by telling the

253
00:13:28.960 --> 00:13:33.320
<v Speaker 2>router to temporarily ignore the startup config stored an envyram.

254
00:13:33.320 --> 00:13:35.000
<v Speaker 2>It's a real life saver if you get locked out.

255
00:13:35.080 --> 00:13:38.960
<v Speaker 1>Exactly. The configuration register is basically the router secret instruction

256
00:13:39.080 --> 00:13:42.159
<v Speaker 1>manual for how to wake up. It really highlights how

257
00:13:42.200 --> 00:13:45.399
<v Speaker 1>tightly coupled the hardware and software are in these devices.

258
00:13:45.519 --> 00:13:47.000
<v Speaker 1>It's like a get out of jail free card.

259
00:13:47.039 --> 00:13:49.080
<v Speaker 2>As you said, definitely one you hope not to use

260
00:13:49.120 --> 00:13:50.960
<v Speaker 2>often on a live network though for sure.

261
00:13:51.360 --> 00:13:54.600
<v Speaker 1>Okay, regular backups absolutely essential. You can save your running

262
00:13:54.600 --> 00:13:57.240
<v Speaker 1>config to startup config and envyram. That saves your current

263
00:13:57.240 --> 00:13:59.320
<v Speaker 1>work so it loads next time. But for a second

264
00:13:59.399 --> 00:14:03.840
<v Speaker 1>off device, copy configurations to a TFTP server, copy running

265
00:14:03.840 --> 00:14:07.440
<v Speaker 1>config TFTP. You can also back up the entire iOS

266
00:14:07.480 --> 00:14:10.799
<v Speaker 1>image itself from flash memory to a TFTP server. Copy

267
00:14:10.799 --> 00:14:12.879
<v Speaker 1>flash TFTP right though.

268
00:14:12.879 --> 00:14:15.799
<v Speaker 2>While TFTP is simple and often built in for those

269
00:14:15.919 --> 00:14:20.320
<v Speaker 2>large iOS files. More reliable protocols like FTP or even

270
00:14:20.360 --> 00:14:24.600
<v Speaker 2>better SCP Secure copy Protocol are generally preferred because they

271
00:14:24.639 --> 00:14:26.559
<v Speaker 2>handle potential transfer errors better.

272
00:14:26.799 --> 00:14:30.039
<v Speaker 1>Good point Now, for dynamic IP address assignment, which is

273
00:14:30.080 --> 00:14:32.960
<v Speaker 1>how most client devices get their IPS automatically, you can

274
00:14:33.000 --> 00:14:36.559
<v Speaker 1>actually configure a DHCP server directly on a Cisco router.

275
00:14:36.960 --> 00:14:39.879
<v Speaker 1>You define the pools of addresses, the default gateways DNS

276
00:14:39.919 --> 00:14:41.879
<v Speaker 1>servers may be addressed to exclude.

277
00:14:42.080 --> 00:14:44.399
<v Speaker 2>And if your main DHCP server isn't on the same

278
00:14:44.440 --> 00:14:47.360
<v Speaker 2>local network segment as the client's needing addresses, you can

279
00:14:47.360 --> 00:14:49.600
<v Speaker 2>figure the router interface facing those clients to act as

280
00:14:49.600 --> 00:14:53.600
<v Speaker 2>a DHCP relay agent. It basically forwards those client DHCP

281
00:14:53.720 --> 00:14:56.000
<v Speaker 2>requests across the network segments to the actual server.

282
00:14:56.320 --> 00:15:01.159
<v Speaker 1>Makes sense, Okay. Inevitably things go wrong, systematic troubleshooting is key.

283
00:15:01.960 --> 00:15:06.480
<v Speaker 1>Cisco recommend a pretty solid four step IP troubleshooting process. First,

284
00:15:06.519 --> 00:15:08.840
<v Speaker 1>ping one twenty seven zero TET zero to a net

285
00:15:08.879 --> 00:15:11.759
<v Speaker 1>one the loop back address. This test your local IP

286
00:15:11.879 --> 00:15:16.159
<v Speaker 1>software stack is TCPIP even running correctly on your machine. Second,

287
00:15:16.200 --> 00:15:18.639
<v Speaker 1>ping your own IP address this test to your network

288
00:15:18.679 --> 00:15:22.360
<v Speaker 1>interface card your NIC. Third, ping your default gateway. This

289
00:15:22.399 --> 00:15:24.679
<v Speaker 1>test local network connectivity to the router, can you reach

290
00:15:24.720 --> 00:15:26.960
<v Speaker 1>the edge of your local network? And finally, ping a

291
00:15:27.000 --> 00:15:29.759
<v Speaker 1>remote server like a public DNS server. This test end

292
00:15:29.759 --> 00:15:31.799
<v Speaker 1>to end connectivity across the wider network.

293
00:15:31.919 --> 00:15:35.639
<v Speaker 2>And that sequence is just incredibly effective because each step

294
00:15:35.759 --> 00:15:38.879
<v Speaker 2>isolates a potential failure point as you quickly figure out

295
00:15:40.159 --> 00:15:43.159
<v Speaker 2>is the problem with my devices, software, my local connection

296
00:15:43.919 --> 00:15:45.720
<v Speaker 2>or is it further out in the network somewhere. Other

297
00:15:45.799 --> 00:15:48.480
<v Speaker 2>super useful commands include trace route on Cisco or trace

298
00:15:48.519 --> 00:15:50.840
<v Speaker 2>rout on Windows that shows you the actual path hop

299
00:15:50.879 --> 00:15:52.759
<v Speaker 2>by hop that your packets are taking to reach a

300
00:15:52.799 --> 00:15:57.080
<v Speaker 2>destination and show interface. Is crucial for checking the physical

301
00:15:57.120 --> 00:15:59.759
<v Speaker 2>and logical status of links. You're looking for things like

302
00:16:00.000 --> 00:16:04.200
<v Speaker 2>Twitter CRC's cyclic redundancy checks or especially duplex mismatches, which

303
00:16:04.240 --> 00:16:05.960
<v Speaker 2>can absolutely kill performance on a link.

304
00:16:06.039 --> 00:16:09.519
<v Speaker 1>Yeah, duplex mismatches are sneaky. Okay. Finally, let's broaden our

305
00:16:09.600 --> 00:16:13.440
<v Speaker 1>view to wide area networks or wands. These connect geographically

306
00:16:13.519 --> 00:16:17.519
<v Speaker 1>separated devices, usually over services provided by carriers. Common one

307
00:16:17.559 --> 00:16:20.639
<v Speaker 1>topologies include the star or hub and spoke full mesh

308
00:16:20.679 --> 00:16:23.440
<v Speaker 1>where everything connects to everything else, highly redundant, put off

309
00:16:23.440 --> 00:16:27.480
<v Speaker 1>and expensive and partial mesh as a compromise. Key one

310
00:16:27.600 --> 00:16:31.000
<v Speaker 1>terms you'll hear are CPE customer premises equipment, that's the

311
00:16:31.000 --> 00:16:34.360
<v Speaker 1>gear at your site, the demarcation point, or that's the

312
00:16:34.399 --> 00:16:38.039
<v Speaker 1>spot usually a physical box where the service provider's responsibility

313
00:16:38.080 --> 00:16:42.000
<v Speaker 1>officially ends and yours begins, and the central office or

314
00:16:42.039 --> 00:16:45.519
<v Speaker 1>point of presence pop basically where your local connection plugs

315
00:16:45.519 --> 00:16:46.879
<v Speaker 1>into the carrier's bigger network.

316
00:16:47.200 --> 00:16:50.639
<v Speaker 2>Right and wands use all sorts of connection types and bandwidths.

317
00:16:50.720 --> 00:16:52.480
<v Speaker 2>You know, from an old T one line at one

318
00:16:52.559 --> 00:16:55.159
<v Speaker 2>point five four to four millipis up to things like

319
00:16:55.200 --> 00:16:57.679
<v Speaker 2>an OC three optical connection at one hundred and fifty

320
00:16:57.720 --> 00:17:00.480
<v Speaker 2>five point five to two millipis or much foul. Now,

321
00:17:00.960 --> 00:17:03.960
<v Speaker 2>dedicated least lines give you a private point to point connection,

322
00:17:04.200 --> 00:17:08.440
<v Speaker 2>often using synchronous serial links. Great for consistent bandwidth. Circuit

323
00:17:08.480 --> 00:17:11.400
<v Speaker 2>switching like old dial up or ISDN, sets up a

324
00:17:11.440 --> 00:17:14.599
<v Speaker 2>temporary dedicated circuit for the duration of the call or connection.

325
00:17:15.160 --> 00:17:18.119
<v Speaker 2>In contrast, packet switching like frame relay in the past

326
00:17:18.279 --> 00:17:22.480
<v Speaker 2>or the modern MPLS multi protocol label switching allows multiple

327
00:17:22.519 --> 00:17:25.480
<v Speaker 2>customers to share the carrier's bandwidth. It's generally more cost

328
00:17:25.559 --> 00:17:28.559
<v Speaker 2>effective and ideal for bursty data traffic, which is most

329
00:17:28.640 --> 00:17:29.720
<v Speaker 2>Internet traffic.

330
00:17:29.359 --> 00:17:32.200
<v Speaker 1>Okay, and for those serial wan links. Two common protocols

331
00:17:32.240 --> 00:17:36.119
<v Speaker 1>are HDLC High Level Data Link Control. It's Cisco's default,

332
00:17:36.400 --> 00:17:36.880
<v Speaker 1>but it's.

333
00:17:36.720 --> 00:17:40.599
<v Speaker 2>Proprietary, meaning a Cisco router running HDLC won't talk to say,

334
00:17:40.720 --> 00:17:43.519
<v Speaker 2>a Juniper router running its version of HDLC. They have

335
00:17:43.599 --> 00:17:44.480
<v Speaker 2>to match, right.

336
00:17:44.559 --> 00:17:47.880
<v Speaker 1>So the alternative is PPP Point to Point Protocol. That's

337
00:17:47.920 --> 00:17:51.519
<v Speaker 1>the industry standard. It supports multiple network layer protocols running

338
00:17:51.519 --> 00:17:55.279
<v Speaker 1>over it, and it has dorthin authentication methods. These include

339
00:17:55.319 --> 00:17:59.039
<v Speaker 1>PAP Password Authentication Protocol, which is less secure because it

340
00:17:59.079 --> 00:18:00.759
<v Speaker 1>sends credentials in clear text.

341
00:18:01.000 --> 00:18:02.519
<v Speaker 2>Again, clear text bad.

342
00:18:02.359 --> 00:18:06.480
<v Speaker 1>Yeah, and the more secure cheering HP Challenge Handshake authentication

343
00:18:06.559 --> 00:18:09.480
<v Speaker 1>protocol that uses a three way handshake and one way

344
00:18:09.480 --> 00:18:11.920
<v Speaker 1>hashing to protect the credentials during authentication.

345
00:18:12.240 --> 00:18:16.039
<v Speaker 2>Much better, definitely, And A really critical troubleshooting point for

346
00:18:16.119 --> 00:18:18.799
<v Speaker 2>ones one that can catch you out is ensuring you

347
00:18:18.880 --> 00:18:22.839
<v Speaker 2>don't have mismatched one encapsulations like having PPP configure it

348
00:18:22.880 --> 00:18:25.079
<v Speaker 2>on one end of the link and HDLC on the other.

349
00:18:25.279 --> 00:18:27.079
<v Speaker 2>The link just won't come up properly at layer two.

350
00:18:27.160 --> 00:18:31.160
<v Speaker 2>It won't work. Also, mismatched IP addresses on PPP links

351
00:18:31.160 --> 00:18:34.039
<v Speaker 2>can be tricky. Sometimes the physical interface might show us

352
00:18:34.160 --> 00:18:38.599
<v Speaker 2>up that the actual PPP protocol negotiation fails, showing protocol down.

353
00:18:39.079 --> 00:18:41.000
<v Speaker 2>You really have to check both the physical status and

354
00:18:41.039 --> 00:18:44.200
<v Speaker 2>the protocol status carefully and look at the routing tables.

355
00:18:44.400 --> 00:18:45.599
<v Speaker 1>Good practical tips there.

356
00:18:45.640 --> 00:18:45.720
<v Speaker 2>So.

357
00:18:45.799 --> 00:18:49.680
<v Speaker 1>Wow, from the noisy chaos cord of hubs all the

358
00:18:49.720 --> 00:18:53.920
<v Speaker 1>way to the precise layered ballet of TCPIP and the

359
00:18:54.039 --> 00:18:57.880
<v Speaker 1>vast interconnected world of wands, we've really navigated the complex

360
00:18:57.960 --> 00:19:01.640
<v Speaker 1>landscape of Cisco networking fundamentals. You've hopefully gained an understanding

361
00:19:01.680 --> 00:19:04.880
<v Speaker 1>of the devices that make networks function, the languages they speak,

362
00:19:05.079 --> 00:19:07.519
<v Speaker 1>and the critical steps for configuring and troubleshooting them.

363
00:19:07.599 --> 00:19:09.599
<v Speaker 2>Yeah, our goal was really to provide you with a

364
00:19:09.599 --> 00:19:14.759
<v Speaker 2>comprehensive yet accessible overview, highlighting those key concepts and practical

365
00:19:14.799 --> 00:19:18.039
<v Speaker 2>insights that go beyond just surface level stuff. You should

366
00:19:18.039 --> 00:19:20.359
<v Speaker 2>now have the foundational knowledge to not just see the

367
00:19:20.359 --> 00:19:23.680
<v Speaker 2>network blinking lights, but to truly understand its underlying structure

368
00:19:24.039 --> 00:19:27.519
<v Speaker 2>and maybe appreciate the ingenious design choices that make our

369
00:19:27.559 --> 00:19:28.680
<v Speaker 2>digital world possible.

370
00:19:28.960 --> 00:19:32.759
<v Speaker 1>Absolutely so, considering the delicate balance we've explored today, that

371
00:19:32.880 --> 00:19:37.039
<v Speaker 1>tension between robust security and seamless successibility. What do you

372
00:19:37.079 --> 00:19:40.519
<v Speaker 1>think is the next major challenge facing network architects as

373
00:19:40.519 --> 00:19:43.559
<v Speaker 1>they try to build truly resilient in future proof networks.

374
00:19:43.799 --> 00:19:45.559
<v Speaker 1>Something for you to think about. That's all for this

375
00:19:45.599 --> 00:19:48.880
<v Speaker 1>deep dives. We hope you feel more informed and ready

376
00:19:48.920 --> 00:19:51.480
<v Speaker 1>to explore the exciting world of networking even further. Until

377
00:19:51.519 --> 00:19:53.200
<v Speaker 1>next time, keep digging deeper.