-: Data center architecture. 2 2
In this lesson, we're going to discuss the architecture 3 3
within our data centers. 4 4
When we're talking about a data center, 5 5
this is any facility that's composed of network, 6 6
computers and storage that businesses 7 7
and other organizations are going to use 8 8
to organize, process, store, 9 9
and disseminate large amounts of data. 10 10
Now that's a pretty generic definition, 11 11
but this is because a data center 12 12
is used to describe a lot of different things these days 13 13
from the very small to the massively large. 14 14
For example, one of the smaller organizations 15 15
I worked for had a small data center 16 16
that was roughly 150 square feet in size. 17 17
Within it, we had a single rack of networking equipment 18 18
and about five racks that contained various servers. 19 19
Now, on the other hand, 20 20
one of the largest data centers in the world 21 21
is located in Bluffdale, Utah. 22 22
This data center is known as the Utah Data Center 23 23
or its official title, 24 24
the Intelligence Community Comprehensive National 25 25
Cybersecurity Initiative Data Center, 26 26
and it is 1.5 million square feet in size 27 27
spread across 20 buildings. 28 28
This data center is massive 29 29
and it uses around 65 megawatts of electricity 30 30
just to run it each day. 31 31
Now this data center costs the US government 32 32
about $1.5 billion to build 33 33
and they spend over $40 million each year 34 34
just on the electricity bills. 35 35
This is a massive data center. 36 36
Now, personally, I haven't worked at that data center, 37 37
but I've worked at some really large data centers. 38 38
But nothing at that size or scale. 39 39
Now, Amazon, for example, 40 40
uses data centers that range in size 41 41
between 150,000 to 215,000 square feet. 42 42
And they host about 50,000 to 80,000 servers 43 43
in each of their data centers. 44 44
As a network technician, 45 45
you may very well end up working 46 46
at one of these data centers one day. 47 47
So let's explore their architecture just a little bit. 48 48
In this lesson, we're going to talk about five key areas. 49 49
The three-tiered hierarchy used by data centers, 50 50
software-defined networking that allows our data centers 51 51
to operate effectively, 52 52
the spine and leaf architecture that's used by data centers, 53 53
the traffic flows that are used by our data centers, 54 54
and the on-premise versus hosted data centers 55 55
and what the differences between them. 56 56
So first let's look at the three-tiered hierarchy 57 57
which consists of the core, 58 58
the distribution or aggregation layer, 59 59
and then the access or edge layer. 60 60
The core layer is going to consist of the biggest 61 61
and fastest and most expensive routers 62 62
that you're ever going to end up working with. 63 63
The core layer is going to be considered the backbone 64 64
of our network 65 65
and it's used to merge geographically separated networks 66 66
into one logical and cohesive unit. 67 67
In general, you're going to have at least two routers 68 68
at the core level operating in a redundant configuration. 69 69
After all, if you only had one core router 70 70
and it went offline, 71 71
the entire network would grind to a screeching halt. 72 72
So we don't want to do that. 73 73
Next, we have the distribution or aggregation layer. 74 74
This layer is located under the core layer 75 75
and it's going to provide boundary definition 76 76
by implementing access control lists and filters. 77 77
Now here at the distribution or aggregation layer, 78 78
we're going to be defining policies 79 79
for the network at large. 80 80
Normally, you're going to see layer three switches 81 81
here being used because this distribution layer 82 82
is going to ensure packets are being properly routed 83 83
between different subnets and VLANs 84 84
within your enterprise network. 85 85
Finally, we're going to get down to the access or edge layer. 86 86
This layer is located beneath the distribution 87 87
or aggregation layer, 88 88
and it's going to be used to connect 89 89
to all of your endpoint devices like your computers, 90 90
your laptops, your servers, your printers, 91 91
your wireless access points, and everything else. 92 92
These access or edge devices 93 93
are going to usually be regular switches, 94 94
and they're going to be used to ensure packets 95 95
are being converted to frames 96 96
and delivered to the correct end point devices when needed. 97 97
Now you may be wondering 98 98
why do I need to use this three-tiered hierarchy? 99 99
Well, by using this type of hierarchy, 100 100
we can get better performance, management, scalability, 101 101
and redundancy from our networks. 102 102
It also is going to give us a better way 103 103
to troubleshoot our network 104 104
because normally if we find an issue, 105 105
we're going to find it and isolate it down to a single access 106 106
or edge layer device. 107 107
Now, we can work on fixing that 108 108
while the rest of the network keeps continuing to operate 109 109
with no issues at all 110 110
and then we can get our network all the way back up 111 111
and running 100%. 112 112
Normally inside your data center, 113 113
you're going to find your core layer devices 114 114
as well as your distribution or aggregation layer devices 115 115
for the local network in that building. 116 116
If you have remote branch offices or other locations, 117 117
each one of those is going to have its own distribution 118 118
or aggregation layer switch inside 119 119
its main distribution frame too. 120 120
In both cases, 121 121
your network will then branch out 122 122
to the intermediate distribution frames 123 123
where you're going to find your access or edge layer devices. 124 124
Now, when we talk about this three-tiered model, 125 125
this is a traditional network 126 126
you're going to find in most enterprises. 127 127
Next, let's move into software-defined networking or SDN. 128 128
Software-defined networking 129 129
is a network architecture approach that enables the network 130 130
to intelligently and centrally be controlled 131 131
or programmed using software applications. 132 132
This helps operators manage 133 133
the entire network consistently and holistically, 134 134
regardless of the underlying network technology. 135 135
Essentially, we're going to take our physical networks 136 136
and we can completely virtualize them 137 137
or create a layer of abstraction 138 138
between the physical devices and the logical architecture 139 139
that they're going to represent. 140 140
Now with software-defined networking, 141 141
we can create complex networks very quickly and easily, 142 142
leveraging increased network size and expanding their scope 143 143
as well as their ability to rapidly change. 144 144
In fact, one of the great things 145 145
about software-defined networks 146 146
is that they can be changed automatically 147 147
by the network itself using automation and orchestration. 148 148
On the other hand, 149 149
all of this rapid change does make it harder for us 150 150
as humans to keep up with it 151 151
and fully understand the data flows on our network 152 152
at any given time. 153 153
Now, when it comes to software-defined networking, 154 154
there are several pieces that we need to consider 155 155
including the application layer, the control layer, 156 156
the infrastructure layer, and the management plane. 157 157
These three layers are going to allow the network 158 158
to be decoupled from the underlying hardware itself. 159 159
The application layer is going to focus 160 160
on the communication resource requests 161 161
or information about the network as a whole. 162 162
The control layer is then going to use that information 163 163
from the applications and decide how to route a data packet 164 164
on that network. 165 165
It also makes decisions about how traffic 166 166
should be prioritized, 167 167
how it should be secured, 168 168
and where it should be forwarded to. 169 169
The infrastructure layer is going to contain 170 170
the actual networking devices that receive the information 171 171
from the control layer about where to move the data, 172 172
and then it's going to perform those movements. 173 173
Now with software-defined networking, 174 174
these underlying infrastructure devices can be physical 175 175
or virtual devices depending on your network configuration 176 176
or a combination or hybrid of the two. 177 177
Remember the whole concept with software-defined networking, 178 178
is probably this layer of abstraction 179 179
between the real underlying devices 180 180
and the control and data flow 181 181
that's going to happen on that network. 182 182
Software-defined networking is also critical for use 183 183
in our successful cloud applications 184 184
because it gives us the scalability and elasticity 185 185
and agility that we need inside those networks. 186 186
Now, the fourth part of software-defined networks 187 187
is our management plane. 188 188
Now the management plane is going to be used 189 189
to monitor traffic conditions and the status of the network. 190 190
Basically, the management plane is going to allow us 191 191
to oversee the network and gain insight into its operations. 192 192
This will also allow us to make configuration changes, 193 193
to set things up the way we want, 194 194
and make sure they're working the way we need them to. 195 195
So for the exam, 196 196
I want you to remember that software-defined networking 197 197
or SDN is broken down into four parts. 198 198
The application layer, the control layer, 199 199
the infrastructure layer, and the management plane. 200 200
Next, let's discuss the spine and leaf architecture. 201 201
Now, the spine and leaf architecture 202 202
is an alternative type of network architecture 203 203
that's used specifically within the data center. 204 204
Now, when we use our three-tiered hierarchy 205 205
that we covered earlier, 206 206
we talked about the fact that we connected 207 207
the core layer down to the distribution layer 208 208
and then down to the access layer or edge layer 209 209
with all of our end point devices. 210 210
With a spine and leaf architecture, 211 211
instead we're going to be focused on communication 212 212
within the data center itself only specifically 213 213
to the server firm and the portions of it. 214 214
The spine and leaf architecture consists 215 215
of two switching layers known as a spine and a leaf. 216 216
Now the leaf layer 217 217
is going to consist of all the access switches 218 218
that aggregate traffic from the different servers 219 219
and then connect directly into the spine layer 220 220
or the networks core. 221 221
This spine contains the switches 222 222
that will interconnect all the leaf layer switches 223 223
into a full mesh topology. 224 224
This leads to increased performance and redundancy 225 225
for all the servers that are connected to the leaf layer 226 226
and in turn to the spine layer. 227 227
Now, as you may be wondering, 228 228
why did I move from the three-tiered networks 229 229
to software-defined networks before starting to discuss 230 230
the spine and leaf architecture? 231 231
Well, this is because many of our spine 232 232
and leaf architectures rely on software-defined networks 233 233
to operate. 234 234
By using a spine and leaf architecture, 235 235
we can actually get faster speeds and lower latency 236 236
than the traditional three-tiered hierarchy as well. 237 237
By using a spine and leaf architecture, 238 238
we can actually take shortcuts 239 239
in getting data from place to place, 240 240
and this all happens best 241 241
when we're using software-defined networks 242 242
in combination with a spine and leaf design. 243 243
If you're installing a spine and leaf architecture, 244 244
normally you're going to install two switches 245 245
into each server rack. 246 246
This is known as top of rack switching 247 247
because the switches are physically installed 248 248
at the very top of the server rack, 249 249
and each server inside that rack 250 250
will have a connection to each of the two switches 251 251
that are residing inside that rack. 252 252
Now, these switches are essentially going to be 253 253
the leafs inside our spine and leaf architecture. 254 254
And they're going to connect back to the spine 255 255
which is going to serve as the backbone 256 256
of our data center network. 257 257
This spine and leaf architecture can also be combined 258 258
with our standard three-tier hierarchy. 259 259
Now, when we do this, 260 260
all the servers in the data center will connect 261 261
to the leaf layers, 262 262
and the leaf layers will connect to the spine. 263 263
But the spine will then connect directly 264 264
to the core layer of the three-tiered model 265 265
whereas all the other non-data center devices 266 266
will connect to the access layer 267 267
and then up to the distribution or aggregation layers 268 268
before connecting into the core layer. 269 269
Next, we need to discuss traffic flows 270 270
in relation to our data centers. 271 271
Now there's two main types. 272 272
We have North-South and East-West. 273 273
These two terms are used to describe 274 274
the direction of traffic flow into or out of a data center. 275 275
Now, when we have North-South traffic, 276 276
this is going to refer to communication traffic 277 277
that enters or leaves the data center 278 278
from a system fiscally residing outside of the data center. 279 279
So when we talk specifically about North traffic, 280 280
this is traffic that is exiting your data center. 281 281
Southbound traffic on the other hand 282 282
is referring to traffic that is entering your data center. 283 283
In both cases, this data is exiting 284 284
or entering the data center going through a firewall 285 285
or other network infrastructure boundary device 286 286
such as a router. 287 287
Conversely, we also have East-West traffic. 288 288
Now, East-West traffic refers to data flow 289 289
within a data center. 290 290
For example, if we're using a spine and leaf architecture, 291 291
any data flow between various servers in the data center, 292 292
even if it goes between different leafs 293 293
would be considered East-West traffic 294 294
because that data is not leaving our data center. 295 295
Now due to the increased use of software-defined networking, 296 296
virtualization, private cloud, and converge networks, 297 297
more and more traffic that we're using 298 298
is being classified as East-West traffic, 299 299
because it's still virtually part of your data center. 300 300
So in summary, 301 301
if the data is entering the data center, 302 302
it's considered Southbound traffic. 303 303
If it's leaving the data center, 304 304
it's considered Northbound traffic. 305 305
If it's moving within the data center, 306 306
it's considered East-West traffic. 307 307
Finally, we need to talk about on-premise 308 308
versus hosted data centers. 309 309
This discussion is really going to come down 310 310
to where are you going to store your data? 311 311
Now, if you're using an on-premise data center, 312 312
you're using a traditional private data infrastructure 313 313
where your organization has its own data center 314 314
that houses all of its servers and networking equipment 315 315
that it's going to use to be able to support its operations. 316 316
We call this on-premise because it's usually located 317 317
in the same building as your main office. 318 318
Sometimes though, you're going to have multiple offices 319 319
spread across a large geographic region or across the globe. 320 320
Normally, one of your offices is going to be considered 321 321
your headquarters and will host your on-premise data center 322 322
in this type of organization. 323 323
And then all the other offices around the globe, 324 324
they'll be called branch offices. 325 325
Now these branch offices 326 326
usually will not host their own servers, 327 327
but instead they will host them 328 328
in your on-premise data center at your headquarters. 329 329
If you have a fast enough connection 330 330
between each branch office and the headquarters, 331 331
you can host everything at your main data center. 332 332
But if you have slower connections, 333 333
you may need to host some services locally 334 334
inside the branch office too. 335 335
For example, when I was an IT director 336 336
for an organization spread across multiple countries, 337 337
we had our own on-premise data center at our headquarters 338 338
where we hosted most of the services 339 339
including our domain controllers, email, proxy servers, 340 340
and other services, 341 341
but we still maintain a local file server 342 342
in each branch office for them to use for their share drives 343 343
because otherwise they would be transferring gigabytes 344 344
and gigabytes of data to and from our data centers 345 345
over a small connection. 346 346
And this would really slow down the entire network. 347 347
Now, this solution for us worked really well 348 348
because the branch office locations 349 349
only need to access their own files on their share drive 350 350
not any files from the main office. 351 351
Now, if they instead need to have a shared file server 352 352
with us at the head office, 353 353
we would have opted for something else 354 354
like a content engine or a caching engine 355 355
instead of using a local file server 356 356
to meet their needs. 357 357
Now, the other option though, 358 358
is to host your data using a co-located data center. 359 359
Now in a co-located data center arrangement, 360 360
your organization places their servers 361 361
and networking equipment in the data center environment 362 362
that's owned by another company. 363 363
Essentially, you're going to rent space in their data center 364 364
instead of having to build your own. 365 365
When I started my very first company back in 1999, 366 366
I was doing website design, website hosting, 367 367
and building network architectures 368 368
for small and medium sized businesses. 369 369
Because I was just starting out, 370 370
I couldn't afford the millions of dollars of the cost 371 371
to make my own data center. 372 372
So we wanted to host our web servers 373 373
and we decided to lease two racks 374 374
in a larger company's data center. 375 375
For a fixed price each month, 376 376
I was able to put whatever equipment I wanted 377 377
that would fit into those two racks 378 378
and they would provide me with a Cat5 connection 379 379
with a hundred megabits per second of bandwidth, 380 380
power, and backup batteries, and generators. 381 381
Beyond that it was up to me to drive their facility, 382 382
install and maintain all my own servers 383 383
and networking equipment 384 384
and run all the configurations I needed. 385 385
Now, the last option we have 386 386
is to move everything into a cloud-based platform 387 387
like Amazon Web Services or Microsoft Azure. 388 388
In those cases we can't use co-location 389 389
because they're not going to allow us put our own servers 390 390
into their facilities. 391 391
Instead we would have to migrate all of our data 392 392
out of our servers and our data centers 393 393
and put them into their servers and their data centers. 394 394
All right, as you can see there are lots of different ways 395 395
to architect your data centers and your networks. 396 396
Everything from a three-tiered traditional model 397 397
to a more modern software-defined network 398 398
that implements spine and leafs to moving completely 399 399
to the cloud. 400 400
It really depends on your business case 401 401
and your organization's needs.