Designing Basic Enterprise Campus Networks Part 1 — Transcript

Full transcript

1. 0:04hi
2. 0:05hello there welcome to designing basic
3. 0:08enterprise campus network
4. 0:11the availability of a multi-gigabit
5. 0:13campus switches
6. 0:14gives customers the opportunity to build
7. 0:17extremely high performance
8. 0:18high reliability networks if they follow
9. 0:22correct network design approaches
10. 0:25unfortunately
11. 0:26some alternative network design
12. 0:28approaches can result in a network that
13. 0:30has a lower performance
14. 0:32reliability and manageability
15. 0:35this video describes a hierarchical
16. 0:38modular design approach
17. 0:39called multi-layer design this
18. 0:42video examines the design of the
19. 0:45enterprise campus
20. 0:46and the enterprise data center network
21. 0:48infrastructures
22. 0:50first it addresses general campus design
23. 0:54considerations
24. 0:55followed by a discussion of a design of
25. 0:58each of the modules
26. 1:00and layers within the enterprise campus
27. 1:03this video concludes with an
28. 1:06introduction to design considerations
29. 1:08for the enterprise data center
30. 1:14now for the topic outline on designing
31. 1:16basic enterprise campus networks
32. 1:19this video has been divided into three
33. 1:21parts or segments
34. 1:23the first part would cover the campus
35. 1:25design considerations
36. 1:27next would be the enterprise campus
37. 1:29design
38. 1:30third would be the enterprise data
39. 1:32center design considerations
40. 1:35and at the end of this video lecture we
41. 1:37are going to summarize each of the
42. 1:39segment
43. 1:40and the entire module
44. 1:45campus design considerations
45. 1:49the multi-layer approach to campus
46. 1:51network design combines
47. 1:52data link layer and multi-layer
48. 1:54switching
49. 1:56to achieve robust high available campus
50. 1:59networks so this section discusses
51. 2:02factors to consider in a campus land
52. 2:06design
53. 2:08let's start with designing the
54. 2:10enterprise campus
55. 2:12the enterprise campus network is the
56. 2:15foundation for enabling business
57. 2:17applications
58. 2:18enhancing productivity and providing a
59. 2:22multitude
60. 2:23of services to end users
61. 2:26so the following three characteristics
62. 2:28should be considered
63. 2:29when designing a campus network so this
64. 2:32includes the network
65. 2:35or network application characteristics
66. 2:39the organizational requirements services
67. 2:42and applications place stringent
68. 2:44requirements on a campus network
69. 2:46solution
70. 2:46for example in terms of bandwidth and
71. 2:49delay
72. 2:51the next one would be the infrastructure
73. 2:54device characteristics
74. 2:57the characteristics of the network
75. 2:59devices
76. 3:00select and influence the design for
77. 3:02example
78. 3:04they determine the network's flexibility
79. 3:07and contribute to overall delay so
80. 3:10trade-offs
81. 3:11between data link layer switching based
82. 3:14on media access control or mac addresses
83. 3:16and multi-layer switching based on the
84. 3:20network layer addresses
85. 3:22transport layer and application
86. 3:24awareness
87. 3:25needed to be considered so high
88. 3:28availability
89. 3:29and high throughput are requirements
90. 3:31that might
91. 3:32require consideration throughout the
92. 3:34infrastructure
93. 3:36so most enterprise campus designs use a
94. 3:39combination
95. 3:40of data link layer switching
96. 3:43in the access layer and multi-layer
97. 3:45switching in the distribution and core
98. 3:47layers
99. 3:48so the next one would be the
100. 3:51environmental characteristics
101. 3:54okay now the network environment
102. 3:57includes each geography and transmission
103. 4:00media used okay the physical environment
104. 4:04of the building or buildings
105. 4:05influences the design as
106. 4:08do the number of distribution distance
107. 4:12between the network nodes
108. 4:13including end users hosts
109. 4:17and network devices so other factors
110. 4:20include space power
111. 4:24heating okay or ventilation and air
112. 4:26conditioning support
113. 4:28for the network devices so cabling is
114. 4:31one of the biggest long-term investments
115. 4:34in network deployment so therefore
116. 4:37transmission media selection depends
117. 4:39not only on the required bandwidth and
118. 4:41distances
119. 4:43but also on the emerging technologies
120. 4:46that might be deployed
121. 4:47over the same infrastructure in the
122. 4:49future
123. 4:54network application characteristics and
124. 4:55considerations so let's talk about the
125. 4:57overview of the network application
126. 5:00types
127. 5:02the network applications characteristics
128. 5:04and requirements
129. 5:05influence the design in many ways
130. 5:08so the applications that are critical to
131. 5:11the organization
132. 5:13and the network demands of the
133. 5:15application
134. 5:16so determine enterprise traffic patterns
135. 5:19inside the enterprise campus network
136. 5:21which influences bandwidth usage
137. 5:25response times and the selection of the
138. 5:28transmission medium
139. 5:30so different types of application
140. 5:32communication result
141. 5:33in varying network demands
142. 5:37so the following section review four
143. 5:39types of application communication
144. 5:41so which are peer-to-peer
145. 5:45you've got a client local server client
146. 5:48server form
147. 5:50and the client enterprise server or ads
148. 5:53server
149. 5:57now these are the network requirements
150. 5:59of applications
151. 6:00so this includes the connectivity type
152. 6:03the
153. 6:04total the high availability rha
154. 6:09and the total network costs
155. 6:13now let's focus on the peer-to-peer
156. 6:16application
157. 6:17here okay so from the network designers
158. 6:20perspective
159. 6:22peer-to-peer applications include
160. 6:24applications in which
161. 6:25the majority of the network traffic
162. 6:27passes from one
163. 6:29network edge device to another through
164. 6:32the organizations
165. 6:33network as shown here in the future okay
166. 6:37so a typical peer-to-peer applications
167. 6:39includes the following
168. 6:41like the instant messaging so after the
169. 6:44connection is established
170. 6:47the conversation is directly between two
171. 6:49peers
172. 6:51okay so you also have the
173. 6:54ip phone calls okay so
174. 6:57two peers established communication with
175. 6:59the help of
176. 7:01an ip telephony manager however the
177. 7:04conversation
178. 7:05occurs directly between the two peers
179. 7:08when the connection is established
180. 7:10the network requirements of the iphone
181. 7:12calls are strict
182. 7:14because of the end of the quality of
183. 7:16service or qos
184. 7:17treatment to minimize delay and
185. 7:19variation in delay or
186. 7:21what we call jitter so next would be
187. 7:25file sharing so some operating systems
188. 7:29and applications require direct access
189. 7:32to data on other workstations
190. 7:36okay so you also have the video
191. 7:39conference systems
192. 7:40okay so video conferencing is similar
193. 7:44to ip telephony however the network
194. 7:46requirements
195. 7:47are usually higher particularly related
196. 7:50to
197. 7:51bandwidth consumption and of course the
198. 7:54quality of service
199. 7:59client local server applications
200. 8:02so historically clients and servers were
201. 8:05attached
202. 8:06to a network device on the same lan
203. 8:08segment
204. 8:10and it follows the 80 20 work group rule
205. 8:13for client server applications so
206. 8:16this rule indicates that 80 of the
207. 8:19traffic
208. 8:20is local to the land segment and 20
209. 8:24percent
210. 8:25leaves the segment so with increased
211. 8:28traffic on the corporate network
212. 8:32and a relatively fixed location for
213. 8:35users
214. 8:36an organization might split the network
215. 8:39into several uh
216. 8:40isolated segments okay so as shown here
217. 8:43in the figure you've got something like
218. 8:45a building access
219. 8:46okay and then you've got the building
220. 8:49distribution campus court
221. 8:51okay so in here
222. 8:54each of the segments has its own servers
223. 8:58known as local servers okay so that is
224. 9:02for each application
225. 9:03now in this scenario servers and
226. 9:06users are located in the same vlan and
227. 9:10department administrators
228. 9:11manage and control the servers
229. 9:16now the majority of the department
230. 9:18traffic occurs in the same segment
231. 9:20but some data exchange okay so to a
232. 9:23different villain
233. 9:25happens over the campus backbone now the
234. 9:28bandwidth requirements for the traffic
235. 9:30passing to another segment typically are
236. 9:32not crucial
237. 9:33okay so for example traffic to the
238. 9:36internet goes through the common segment
239. 9:38and has a lower performance requirements
240. 9:41than traffic to the local segment
241. 9:43servers
242. 9:49another is the client server farm
243. 9:51applications
244. 9:53so large organizations require their
245. 9:56users
246. 9:57to have fast reliable
247. 10:00and controlled access to critical
248. 10:02applications
249. 10:04because high-performance multi-layer
250. 10:06switches have a
251. 10:07insignificant switch delay and because
252. 10:10of the reduced cost
253. 10:11of the network bandwidth locating the
254. 10:14server centrally
255. 10:15rather than in the work group is
256. 10:18technically feasible
257. 10:19and reduces support costs so
258. 10:22to fulfill demands okay and keep
259. 10:26administrative costs down
260. 10:28the servers are located in a common
261. 10:31server
262. 10:32farm so as shown here in the future so
263. 10:34all the server of the organization
264. 10:36was deployed on the server form
265. 10:39so using a server form requires a
266. 10:42network infrastructure
267. 10:44that is highly resilient when you say
268. 10:46resilient or highly resilient
269. 10:48it provides security and redundancy
270. 10:52okay so providing high availability
271. 10:55and that provides adequate throughput
272. 10:57also
273. 10:59now high-end land switches with the
274. 11:02fastest land technologies such as
275. 11:04gigabit ethernet are typically deployed
276. 11:07in such environment
277. 11:11okay so typical applications basically
278. 11:15that includes
279. 11:16mail servers file servers database
280. 11:18servers
281. 11:19okay and then access to applications
282. 11:23it should be fast as i mentioned earlier
283. 11:25reliable and
284. 11:26controlled or it should be secure
285. 11:32client server farm applications okay
286. 11:35now in a large organization application
287. 11:38traffic might have to pass across
288. 11:41more than one wiring closets okay or the
289. 11:44telecommunication closet
290. 11:46lan or vlan to reach server
291. 11:49in a server form now client server farm
292. 11:52applications apply
293. 11:54the 2080 rule where only 20 percent of
294. 11:57the
295. 11:57traffic remains in the local land
296. 11:59segment
297. 12:00and 80 percent leaves the segment to
298. 12:03reach
299. 12:04centralized servers the internet
300. 12:07and so on so such applications
301. 12:10includes the following so such as the
302. 12:13organizational mail server so those who
303. 12:16are using microsoft exchange
304. 12:18okay common file server such as
305. 12:22microsoft and sun microsystems
306. 12:25okay if there are still some
307. 12:26microsystems being used nowadays but
308. 12:28then
309. 12:29mostly most of us are using a microsoft
310. 12:32operating system
311. 12:35also common database servers for
312. 12:37organizational
313. 12:38applications such as oracle okay
314. 12:41so you also have the client enterprise
315. 12:45edge applications so shown here in the
316. 12:48figure
317. 12:49client enterprise edge application use
318. 12:52servers
319. 12:53on the enterprise edge okay that is to
320. 12:56exchange data between the organization
321. 12:58and its public servers
322. 13:00so the most important issues between the
323. 13:02enterprise campus
324. 13:04network and the enterprise edge are
325. 13:07security okay and also
326. 13:11the high availability data exchange
327. 13:14with external entities must be in
328. 13:17constant
329. 13:18operation all right
330. 13:21so applications installed on the
331. 13:23enterprise edge
332. 13:24can be crucial to organizational uh
333. 13:27process flow
334. 13:29okay so therefore any outages can
335. 13:32increase
336. 13:33costs
337. 13:37okay so next would be the relative
338. 13:40network requirements by application type
339. 13:43so we have here on this table
340. 13:47okay so it lists the types of
341. 13:49application communication
342. 13:50and compares their requirements
343. 13:54with respect to some important network
344. 13:56parameters
345. 13:58right so like connectivity okay so let's
346. 14:01start with connectivity here
347. 14:03okay so on connectivity the wide use of
348. 14:07lan switching
349. 14:08at layer 2 has revolutionized local
350. 14:12area networking and has resulted
351. 14:16in increased performance and more
352. 14:19bandwidth for satisfying the
353. 14:20requirements
354. 14:21of new organizational applications
355. 14:25so land switches provides these
356. 14:27performance benefits
357. 14:29by increasing bandwidth and throughput
358. 14:31for work groups and
359. 14:33local servers now you have heard me
360. 14:36saying
361. 14:37to put okay so what is a throughput
362. 14:41so the required to put varies from
363. 14:43application to application
364. 14:46an application that exchanges data
365. 14:48between users
366. 14:49in the work group usually does not
367. 14:52require a high throughput
368. 14:53network infrastructure however
369. 14:56organizational level applications
370. 14:58usually require
371. 14:59a high capacity link to the servers
372. 15:02which are usually located in the server
373. 15:05form
374. 15:06right so next would be high availability
375. 15:11so what is a high availability or ha
376. 15:15the high availability of an application
377. 15:18is a function of the application and the
378. 15:21entire network between a client
379. 15:23workstation and the server
380. 15:25located in the network so although the
381. 15:28network design primarily determines the
382. 15:30network's availability
383. 15:32the individual components mean time
384. 15:35between failures or the
385. 15:36mtbf okay that is a factor
386. 15:41okay so redundancy in the building
387. 15:43distribution
388. 15:44and campus score layer is recommended
389. 15:49next would be the total network cost
390. 15:52so depending on the application and the
391. 15:54resulting network infrastructure
392. 15:57the cost varies from low in a
393. 16:00peer-to-peer environment
394. 16:01to high in a network with redundancy in
395. 16:04the building distribution
396. 16:06campus core and server farm
397. 16:10okay so in addition to the cost
398. 16:13of duplicate components for redundancy
399. 16:16cost includes
400. 16:18of course the cables right uh routers
401. 16:22switches software and others
402. 16:28environmental characteristics for
403. 16:30network design
404. 16:31so what are the environmental
405. 16:33characteristics and considerations
406. 16:36so the campus network environment
407. 16:39including the location of the network
408. 16:41nodes
409. 16:42and the distance between the nodes and
410. 16:45the transmission media used
411. 16:46influences the network topology so this
412. 16:49section examines
413. 16:51this consideration okay so this
414. 16:54includes the network geography
415. 16:58okay or the network geography
416. 17:00consideration
417. 17:01this pertains to the location of the
418. 17:04enterprise campus nodes
419. 17:06and the distances between them determine
420. 17:09the network's
421. 17:10geography now nodes including
422. 17:14end user workstations and servers can be
423. 17:17located in
424. 17:18one or multiple buildings okay
425. 17:21so based on the location of the nodes
426. 17:23and the distance between them
427. 17:25the network designer decides which
428. 17:27technology
429. 17:29should interconnect them based on the
430. 17:30required maximum
431. 17:32speed distance and so forth
432. 17:35okay considering the following
433. 17:37structures with respect to
434. 17:39network geography so you've got sort of
435. 17:42the intra building
436. 17:44okay inter inter-building and distant
437. 17:46remote
438. 17:47building
439. 17:51intra-building structure an
440. 17:54inter-building campus network structure
441. 17:56provides connectivity
442. 17:58for all end nodes located in the same
443. 18:01building
444. 18:02and gives them access to the network
445. 18:04resources
446. 18:06the building access and the building
447. 18:08distribution layer
448. 18:10are typically located on the same
449. 18:12building
450. 18:13okay so user workstations
451. 18:17are usually attached to the building
452. 18:19access switches
453. 18:20in the floor wiring closet with twisted
454. 18:23pair
455. 18:24copper cables so some are using wireless
456. 18:27lan or wlan
457. 18:29that can also be used to provide
458. 18:31intra-building connectivity
459. 18:34enabling users to establish and maintain
460. 18:38a wireless network connection
461. 18:40throughout or between buildings without
462. 18:42the limitations of
463. 18:44wires and cables okay
464. 18:47now access layer switches usually
465. 18:49connect the building distribution
466. 18:51switches
467. 18:52over fiber optic cable okay
468. 18:55or optical fiber providing better
469. 18:58transmission performance
470. 18:59and less sensitivity to environmental
471. 19:01disturbances
472. 19:03compared to copper so depending on the
473. 19:06connectivity requirements
474. 19:08to resources in other parts of the
475. 19:11campus
476. 19:12the building distribution switches may
477. 19:14be connected
478. 19:15to campus course switches
479. 19:20how about inter-building structure now
480. 19:24as shown here in the figure
481. 19:26an inter-building network structure
482. 19:27provides connectivity between the
483. 19:29individual campus buildings
484. 19:32central switches that is in the building
485. 19:34distribution
486. 19:35and or campus core layers
487. 19:38now these buildings here a and b are
488. 19:41usually in close proximity
489. 19:43so typically only a few hundred meters
490. 19:46to a few kilometers apart
491. 19:49so because the nodes in all the campus
492. 19:51buildings usually share common devices
493. 19:54such as servers okay
494. 19:57the demand for high speed connectivity
495. 19:59between the building aside
496. 20:02right so within the campus companies
497. 20:05might deploy their own physical
498. 20:07transmission media
499. 20:09so to provide high throughput without
500. 20:11excessive interference
501. 20:13from environmental conditions optical
502. 20:16fiber is the medium okay
503. 20:20so that is basically to connect these
504. 20:23two buildings here
505. 20:24so depending on the connectivity
506. 20:26requirements to resources
507. 20:28in other parts of the campus the
508. 20:31building distributions which just might
509. 20:33be
510. 20:34connected to the compost core switches
511. 20:41distant remote building structure so
512. 20:44when connecting buildings at a distance
513. 20:48or distances that exceed a few
514. 20:50kilometers but still
515. 20:52within a metropolitan area the most
516. 20:55important factor to consider
517. 20:57is the physical media okay so the speed
518. 21:00and cost
519. 21:01of the network infrastructure depends
520. 21:04heavily on the media selection
521. 21:07so if the bandwidth requirements are
522. 21:09higher than the physical connectivity
523. 21:11options can support
524. 21:12the network designer must identify the
525. 21:15organization's critical applications
526. 21:18and then select equipment that supports
527. 21:20intelligent network services such as
528. 21:22the qos or the quality of service and
529. 21:26filtering capabilities that allow
530. 21:27optimal use of the bandwidth
531. 21:31okay so for the metropolitan based
532. 21:34network connectivity options
533. 21:36so using a company on fiber okay
534. 21:40through the enterprise wide area network
535. 21:42or through service provider offerings
536. 21:44via your isp
537. 21:50campus transmission vision so let's talk
538. 21:53about the transmission media
539. 21:54considerations
540. 21:56so an enterprise campus can use various
541. 21:59physical media to interconnect devices
542. 22:02so the type of cable is an important
543. 22:04consideration
544. 22:06when deploying a new network or
545. 22:08upgrading an existing one
546. 22:11so cabling infrastructure represents a
547. 22:13long-term investment
548. 22:15it is usually installed to last for 10
549. 22:18years or even more
550. 22:20okay so the cost of the medium including
551. 22:23the installation costs
552. 22:24and the available budget must be
553. 22:27considered in addition to technical
554. 22:28characteristics
555. 22:30such as signal attenuation
556. 22:33and electromagnetic interferences
557. 22:37okay so the options would be
558. 22:40of course the fiber optic or the optical
559. 22:43fiber
560. 22:45so typically requirements that lead to
561. 22:48the selection of the
562. 22:49optical fiber cable as our transmission
563. 22:53medium includes
564. 22:54distances longer than 100 meters
565. 22:57and of course the immunity to
566. 22:59electromagnetic interferences
567. 23:02so different types of optical fiber
568. 23:05or optical cable exist so the two main
569. 23:08types are of course the
570. 23:10multi-mode or mm
571. 23:13and the single mode or sm
572. 23:16okay now the difference would be
573. 23:19mm or the multi-mode fiber is optical
574. 23:22fiber that carries multiple light waves
575. 23:25or modes concurrently so each
576. 23:29at a slightly different reflection angle
577. 23:32within the optical
578. 23:33fiber core now because
579. 23:37modes tend to disperse over longer
580. 23:40lengths
581. 23:40or model dispersion the multi-mode
582. 23:44fiber transmission is used for
583. 23:46relatively
584. 23:47short distances so typically
585. 23:50leads are used with the multi-mode fiber
586. 23:54so the typical diameter of a multi-mode
587. 23:57fiber is 50
588. 23:59or 62.5 micrometers
589. 24:03okay so a single mode also known as the
590. 24:06mono mode fiber is optical fiber that
591. 24:08carries a single wave or laser applied
592. 24:13so lasers are typically used with single
593. 24:16mod
594. 24:16fibers so the typical diameter of a
595. 24:19single mode fiber
596. 24:21is between 2 to 10 micrometers
597. 24:24okay now a single mod fiber limits
598. 24:27dispersion
599. 24:28and loss of light and therefore allows
600. 24:31for higher transmission speeds
601. 24:34but it is more expensive than multi-mode
602. 24:37fiber
603. 24:38so both multi-mode and single mode
604. 24:41cables have lower loss
605. 24:42of signal than copper cable so therefore
606. 24:46optical cables allows
607. 24:49longer distances between devices should
608. 24:52use
609. 24:53an optical fiber okay so
610. 24:56optical fiber cable has precise
611. 24:58production
612. 24:59and installation requirements therefore
613. 25:02it costs more than our traditional cable
614. 25:06which is the utp or the twisted pair
615. 25:12cable
616. 25:14comparison of campus transmission media
617. 25:17so the parameters listed on this table
618. 25:20are as follows
619. 25:21so basically you've got distance
620. 25:23bandwidth
621. 25:24and the price okay now let's
622. 25:28take distance first okay
623. 25:31the maximum distance between network
624. 25:34devices such as workstations
625. 25:36servers printers what else iphones
626. 25:41and network nodes and between network
627. 25:43nodes
628. 25:45okay the distances supported with fiber
629. 25:48vary
630. 25:49depending on whether it supports fast
631. 25:51ethernet
632. 25:53or gigabit ethernet and the type of
633. 25:55fiber
634. 25:56used and the fiber interpreter is used
635. 25:59also
636. 26:00okay so it would depend whether you're
637. 26:03using copper
638. 26:04the multi-mode fiber the single mode or
639. 26:07even wireless
640. 26:09okay now for the bandwidth
641. 26:12the required bandwidth in a particular
642. 26:14segment of the network
643. 26:16or the connection speed between the
644. 26:17nodes inside or outside
645. 26:20the building okay so
646. 26:23another factor is price or cost
647. 26:26along with the price of the medium so
648. 26:29the installation
649. 26:30cost must be considered okay
650. 26:33so for example fiber installation costs
651. 26:37are significantly higher
652. 26:38than copper installation costs because
653. 26:41of
654. 26:42strict requirements for optical fiber
655. 26:45or optical cable coupling
656. 26:50right
657. 26:52so let's have an example here okay so
658. 26:55transmission media
659. 26:56now this figure here illustrates a
660. 26:58typical campus network
661. 27:00structure so each devices such as
662. 27:04a workstation iphones and printers
663. 27:08are no more than 100 meters away from
664. 27:10the lan switch
665. 27:12okay so utp wiring can easily handle
666. 27:16the required distance and speed it is
667. 27:19also
668. 27:20easy to say that well this is the most
669. 27:23economical solution
670. 27:25okay so to connect devices within the
671. 27:28network
672. 27:29or within the local area network and the
673. 27:32price performance ratio is of course
674. 27:34reasonable so optical fiber cables
675. 27:38handle the higher speeds and distances
676. 27:41that may be required among switch
677. 27:44devices
678. 27:46so something like to connect this um
679. 27:49four switches here then our option best
680. 27:52option
681. 27:53is to use the fiber optic cable so
682. 27:56multi-mode optical cable
683. 27:58is usually satisfactory inside the
684. 28:01building
685. 28:02okay so depending on the distance
686. 28:05organization's
687. 28:06use of the multi-mode or single mode
688. 28:08optical uh for inter-building
689. 28:09communication cable
690. 28:11then it has to be considered okay
691. 28:14so multi-mode or single mode that's fine
692. 28:17all right now if the distances are short
693. 28:21say up to 500 meters multi-mode fiber
694. 28:25is a more reasonable solution for speeds
695. 28:28up to 1 gbps however
696. 28:31an organization can install a single mod
697. 28:35fiber
698. 28:36if its requirements are for longer
699. 28:39distances
700. 28:40or if there are plans for future higher
701. 28:43speeds for example 10 gbps
702. 28:46within the network so when you design
703. 28:49a network again you have to consider
704. 28:53okay the future so do not just design a
705. 28:55network that is based on the current
706. 28:59requirements okay so you have to
707. 29:01consider at least
708. 29:0210 years
709. 29:07infrastructure device characteristics
710. 29:09and considerations
711. 29:12so network and user devices are commonly
712. 29:14connected using switch
713. 29:16okay or the switch technology rather
714. 29:19than using shared media segment
715. 29:21okay so switch technology provides a
716. 29:24dedicated network bandwidth
717. 29:27for each device on the network
718. 29:30so switch networks can support
719. 29:33network infrastructure services such as
720. 29:36the quality of service
721. 29:38okay security management
722. 29:41okay a shared media segment cannot
723. 29:43support these features
724. 29:46now in the past land switches were layer
725. 29:492 only devices
726. 29:51so data link layer or layer 2 switching
727. 29:53supports multiple simultaneous frame
728. 29:56flaws
729. 29:58the multi-layer switching performs
730. 29:59packet switching
731. 30:01and several functions at layer 3
732. 30:04and at higher open systems
733. 30:07interconnection or the osi layers
734. 30:09and can effectively replace routers in
735. 30:12the lan switch
736. 30:13environment now deciding whether to
737. 30:16deploy
738. 30:17if your data link layer switches or
739. 30:20a multi-layer switches in the enterprise
740. 30:22network is not a trivial decision
741. 30:25okay so it requires a full understanding
742. 30:28of the network topology
743. 30:30and user demands and basically
744. 30:33in network design everything will boil
745. 30:36down to
746. 30:37cost
747. 30:41now let's have an example of the network
748. 30:43services
749. 30:45okay the quality of service in lan
750. 30:48switches
751. 30:50okay so when configuring the quality of
752. 30:52service feature
753. 30:54classify the specific network traffic
754. 30:57prioritize and market according to
755. 30:59its relative importance and use
756. 31:02congestion management
757. 31:04and policy and shaping also
758. 31:07okay to provide preferential treatment
759. 31:10so take note that in design we have to
760. 31:13give the highest priority to
761. 31:15voice okay so that is to ensure the
762. 31:18quality of service
763. 31:20now implementing the qos in the network
764. 31:22makes the network performance
765. 31:24more predictable and bandwidth use more
766. 31:27effective
767. 31:29now this figure here illustrates
768. 31:32where various categories of qos may be
769. 31:35implemented
770. 31:36in the land switches okay
771. 31:39now data link layer switches are
772. 31:41commonly used in
773. 31:43the building acts layer because they do
774. 31:47not have knowledge
775. 31:48of the layer 3 or higher information
776. 31:51this switches provides
777. 31:52quality of service classification and
778. 31:54marking
779. 31:55based only on the switches input port
780. 31:58or mac addresses so for example
781. 32:02traffic from a particular host can be
782. 32:05defined
783. 32:06as high priority traffic on the uplink
784. 32:10port
785. 32:11okay so multi-layer switches can be used
786. 32:14in the building access layer
787. 32:16if layer three services are required
788. 32:20now building distribution okay
789. 32:23or the building distribution layer the
790. 32:25campus core layer and the server form
791. 32:27switches
792. 32:28are typically multi-layer switches and
793. 32:32that should provide the quality of
794. 32:34service selectively
795. 32:36not only on the port basis but also
796. 32:39according to higher layer parameters
797. 32:41such as
798. 32:42ip addresses port numbers
799. 32:45or quality of service bits in the ip
800. 32:48packet
801. 32:50so just switches makes the qos
802. 32:53classification more selective
803. 32:55by differentiating the traffic based on
804. 32:58the application
805. 33:00so quality of service or qos in
806. 33:02distribution and core switches
807. 33:05must be provided in both directions of
808. 33:08the traffic flow
809. 33:10so the policy for certain traffic is
810. 33:13usually implemented
811. 33:14on the distribution layer switches
812. 33:21all right so to summarize the campus
813. 33:24design considerations
814. 33:26okay so campus network design
815. 33:30is influenced by several factors
816. 33:32mentioned
817. 33:33okay so first by application
818. 33:35characteristics
819. 33:36such as throughput and availability
820. 33:40requirements
821. 33:42second are environmental characteristics
822. 33:45such as the location
823. 33:47okay and buildings
824. 33:50okay and of course the transmission
825. 33:52media being used to connect these
826. 33:53devices and buildings
827. 33:55and then third the infrastructure device
828. 33:58characteristics
829. 34:00such as switching type and support for
830. 34:03network services