Applying Methodology to a Design Part 5 — Transcript

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1. 0:04using the top-down approach
2. 0:06to network design so this is the fifth
3. 0:09installment of the applying methodology
4. 0:13to a design
5. 0:18using the top-down approach to network
6. 0:21design
7. 0:23so after establishing the organizational
8. 0:25requirements and documenting the
9. 0:27existing network
10. 0:28the designer is ready to design the
11. 0:31network solution
12. 0:33this section first discusses the
13. 0:35top-down approach
14. 0:36the network design decision tables and
15. 0:39structure designs
16. 0:41are described and the section includes a
17. 0:44brief discussion
18. 0:45of the types of network design tools
19. 0:48that might be used
20. 0:50so this section concludes with a
21. 0:53discussion about building a pilot or
22. 0:55prototype
23. 0:57and the contents of a detailed design
24. 0:59document
25. 1:00let's get started
26. 1:04up down approach to network design so
27. 1:07basically
28. 1:08this is based on the osi layer
29. 1:12okay or the internet model okay
30. 1:16so you've got the osi and the ieee
31. 1:19tcp model okay with
32. 1:24the osi layers we are considering the
33. 1:26seven layers
34. 1:27versus the four layers of the tcpip
35. 1:30model
36. 1:31okay now designing a large or even
37. 1:34medium-sized network
38. 1:36can be a complex project procedures have
39. 1:40been developed
40. 1:41to facilitate the design process by
41. 1:43dividing it into smaller
42. 1:45more manageable steps so identifying the
43. 1:48separate steps
44. 1:50or tasks
45. 1:53a smooth process and reduces potential
46. 1:57risks so a top-down design
47. 2:01allows the designer to see the big
48. 2:02picture before
49. 2:04getting to the details so top design
50. 2:07clarifies the design goals and initiate
51. 2:11the design
52. 2:11from perspective of the required
53. 2:14applications so the top-down approach
54. 2:18adapts
55. 2:19the physical infrastructure of the needs
56. 2:23of the applications network devices are
57. 2:26chosen only
58. 2:27after a thorough requirement analysis
59. 2:31so structured design practices should be
60. 2:34integrated with a top-down approach
61. 2:36especially in a very complex networks
62. 2:41so top-down approach started with the
63. 2:43application layer downward
64. 2:45okay while the bottom up is of course
65. 2:48the opposite
66. 2:50so in contrast to the top down design
67. 2:53the network design approach in which the
68. 2:56network devices and technologies
69. 2:58are selected first is called the bottom
70. 3:01up
71. 3:01or connect the dots so this approach
72. 3:06often results in an appropriate network
73. 3:09for the required services and is
74. 3:11primarily used
75. 3:13when a very quick response to the design
76. 3:15request is needed
77. 3:17so with bottom up approach the risk of
78. 3:20having the red design
79. 3:21the network is very high
80. 3:28so guidelines for producing a top-down
81. 3:30design
82. 3:31includes the following so totally
83. 3:34analyze the customer requirements
84. 3:37okay so that's number one as always
85. 3:39customer
86. 3:40requirements initiate the design
87. 3:43from the top of the osi model which is
88. 3:45the application layer
89. 3:47okay so in other words define the upper
90. 3:50osi layers
91. 3:51application presentation and session
92. 3:53first
93. 3:54and then define the lower osi layers
94. 3:58transport network data link and physical
95. 4:00layer
96. 4:01the infrastructure routers switches and
97. 4:05media
98. 4:05that is required so take note that from
99. 4:09the fundamentals of networking
100. 4:11okay so every devices is working on the
101. 4:14specific layer of the osa model so you
102. 4:16have to know
103. 4:17what specific device is operating on
104. 4:19which layer
105. 4:21so also you need to gather additional
106. 4:23data about the network
107. 4:25protocol behavior scalability
108. 4:28requirements additional requirements
109. 4:30from the customer and so forth
110. 4:32so that might influence the logical and
111. 4:34physical design
112. 4:37adapt the design to the new data as
113. 4:40required
114. 4:42now the top-down approach compared to
115. 4:45bottom-up approach
116. 4:47okay so a top-down approach to design
117. 4:50has many benefits
118. 4:52so compared to up approach
119. 4:56including the following shift got
120. 4:58incorporating the customer organization
121. 5:00requirements
122. 5:02okay so providing the customer and the
123. 5:04designer
124. 5:06with a big picture of the desired
125. 5:09network
126. 5:10also providing a design that is
127. 5:13appropriate
128. 5:14for both current requirements and future
129. 5:17development
130. 5:18so the disadvantage of a top-down
131. 5:20approach is that
132. 5:22it is more time-consuming than bottom-up
133. 5:25approach
134. 5:27okay it necessitates a requirement
135. 5:29analysis
136. 5:30so that the design can be adapted to the
137. 5:33identified needs
138. 5:36so a benefit of a bottom-up approach
139. 5:39selecting the devices and technologies
140. 5:42and then moving towards services and
141. 5:44applications
142. 5:47is that it allows a quick response to a
143. 5:50design request
144. 5:52the major disadvantage of the bottom up
145. 5:55approach
146. 5:57is that it can result in an appropriate
147. 6:00design
148. 6:01okay leading to costly redesign
149. 6:08top-down example okay
150. 6:12so consider an example that uses the
151. 6:15basics
152. 6:15of top-down approach when designing an
153. 6:18ip telephony
154. 6:19okay network solution so in this example
155. 6:23the customer requires a network that can
156. 6:25support
157. 6:26ip telephony or the voip okay
158. 6:30so ip telephony permits the use of the
159. 6:33same network
160. 6:34resources for both data and voice
161. 6:36transport
162. 6:37thus reducing the cost of having two
163. 6:40separate networks
164. 6:42so to achieve this the network must
165. 6:45support
166. 6:46voip or voice over ip technology
167. 6:50this first step in the design process
168. 6:54is illustrated on this diagram here
169. 6:59all right so the figure illustrates the
170. 7:02addition
171. 7:03of ip based network
172. 7:06which is required to support voip
173. 7:09so the network includes ip enabled
174. 7:12routers and other devices
175. 7:14not shown in the figure so ip
176. 7:17networks delay is also managed
177. 7:22okay via the quality of service so to
178. 7:25achieve that
179. 7:26specific uos or quality of service
180. 7:28mechanisms are also
181. 7:30implemented in the network
182. 7:35now this figure illustrates the addition
183. 7:37of call monitoring
184. 7:40okay and management function
185. 7:44this function was previously overlooked
186. 7:46because such
187. 7:47function were traditionally handled by
188. 7:50pbx okay that is on a separate
189. 7:54voice network during the top top-down
190. 7:57design
191. 7:58it became clear that this function is
192. 8:01necessary
193. 8:02so you could have the unified
194. 8:04communication manager
195. 8:06is therefore placed inside the network
196. 8:08to manage and monitor
197. 8:09ip telephone calls
198. 8:14decision tables in network design so
199. 8:17that is creating a network decision
200. 8:19table
201. 8:20decision tables are used for making
202. 8:22systematic decisions
203. 8:25when there are multiple solutions or
204. 8:28options
205. 8:29to a network issue or problem
206. 8:33decision tables facilitates the
207. 8:35selection of the most
208. 8:36appropriate option from many
209. 8:38possibilities and can be helpful
210. 8:41for justifying why a certain solution
211. 8:44was chosen
212. 8:46options are usually selected based on
213. 8:48the highest level of compliance
214. 8:52with a given requirements
215. 8:55so basic guidelines for creating a
216. 8:57network design decision table
217. 9:00includes the following first
218. 9:03determine the network building block
219. 9:06about which decisions will be made
220. 9:10so that includes the physical topology
221. 9:14okay so routing protocols security
222. 9:17implementation
223. 9:18and so on okay step two
224. 9:22collect possible options
225. 9:25for each decision
226. 9:29okay so be certain to include all
227. 9:32options
228. 9:34or as many as possible to obtain maximum
229. 9:37value from the decision table
230. 9:39so a total survey of the existing state
231. 9:42of technology
232. 9:43and considerable knowledge are needed to
233. 9:45include
234. 9:46all options next would be
235. 9:50create a table that includes
236. 9:53the possible options of the given
237. 9:55requirements
238. 9:56include the relevant parameters or
239. 9:59properties
240. 10:01next would be match the given
241. 10:04requirements with the specific
242. 10:05properties
243. 10:06of the given options select
244. 10:10the most appropriate option the option
245. 10:13with the most matches
246. 10:16if all requirements are treated equally
247. 10:18however
248. 10:19if some requirements are considered more
249. 10:21important than others
250. 10:23implement a weighing system such as each
251. 10:26of the requirement
252. 10:27is assigned a weight that is
253. 10:29proportional to its
254. 10:30importance in decision making process
255. 10:36so this diagram here is an example of
256. 10:39decision table
257. 10:40for selecting a routing protocol based
258. 10:42on multiple criteria
259. 10:44okay now in this example
260. 10:48several routing protocols are considered
261. 10:51like eigrp
262. 10:54ospf and bgp
263. 10:58so five required parameters are listed
264. 11:00along with the indication of how well
265. 11:02the routing protocols comply
266. 11:04with these requirements so we have some
267. 11:07video lectures about this
268. 11:09routing protocols now as indicated in
269. 11:12the future the chosen protocol should
270. 11:15include the following properties
271. 11:18first it should support a large network
272. 11:21okay so all protocols here
273. 11:25considered meet these requirements so
274. 11:28all of these protocols here are
275. 11:29compatible with a large or very large
276. 11:32network all right next
277. 11:36it must be enterprise focus rather than
278. 11:38internet service provider focus
279. 11:41so bgp was designed to support
280. 11:44interconnecting networks
281. 11:46for autonomous systems it is not
282. 11:48optimized
283. 11:49for use in the enterprise isis
284. 11:53is typically deployed in the service
285. 11:56provider environments rather than
286. 11:57the enterprises next would be
287. 12:01the support for the variable length
288. 12:03subnet mask
289. 12:04or vlsm is required so all the protocols
290. 12:07being considered
291. 12:09supports vlsm okay
292. 12:13next would be it must be supported on
293. 12:15cisco routers
294. 12:16which is the case for all the protocols
295. 12:19being considered
296. 12:20so basically all of this works with
297. 12:24cisco routers all right it's just that
298. 12:27eigrp
299. 12:29is customized for the cisco device
300. 12:31because eigrp is a proprietary protocol
301. 12:34and that is for cisco all right
302. 12:39next would be network support staff
303. 12:41should have a good knowledge of the
304. 12:43chosen protocol to enable them
305. 12:45to troubleshoot the network so in this
306. 12:48case
307. 12:49the network support staff are
308. 12:51knowledgeable about
309. 12:52eigrp but not about
310. 12:56ospf okay bgp
311. 13:00or isis well basically this is an
312. 13:02example
313. 13:03all right this is just an example and
314. 13:06based on the
315. 13:07stated requirements well eigrp is the
316. 13:09routing protocol
317. 13:11of choice in this example
318. 13:19next would be assessing the scope of the
319. 13:21network design process
320. 13:23so what would be the scope of the
321. 13:24network design is it the entire network
322. 13:28is it the campus or the one
323. 13:31okay so you should have identified
324. 13:34the scope of your network design
325. 13:39also we have an example of assessing the
326. 13:43scope of the network design process
327. 13:46based on the
328. 13:47osi layer okay on the application layer
329. 13:50designing voice transport on the network
330. 13:54basically designing routing and ip
331. 13:57addressing
332. 13:58okay and on the physical data link
333. 14:01choosing a connection type so that is
334. 14:03based on this
335. 14:04seven layers of the osi model
336. 14:09structure design so the output of the
337. 14:13design
338. 14:14should be a model of the complete system
339. 14:18okay the top down approach is highly
340. 14:22recommended
341. 14:23so rather than focusing on the network
342. 14:25components technologies or protocols
343. 14:28instead of focus on business goals
344. 14:31technical objectives and existing and
345. 14:33future network applications and services
346. 14:36so structured design focuses on
347. 14:38systematic approach
348. 14:40dividing the design task into related
349. 14:44less complex components as follows
350. 14:47so first identify the applications
351. 14:50needed to support the customer
352. 14:52requirements
353. 14:54next would be identify the application's
354. 14:56logical connectivity requirements
355. 14:59where the focus on the necessary
356. 15:02infrastructure services
357. 15:04and network infrastructure next should
358. 15:07be
359. 15:07split the network functionally to
360. 15:10develop the
361. 15:12network infrastructure and hierarchical
362. 15:14requirements
363. 15:16okay and then design each of the
364. 15:19functional elements separately
365. 15:21okay yet the relation okay
366. 15:24two other elements should be there
367. 15:27so for example the network
368. 15:29infrastructure and infrastructure
369. 15:31services designs are tightly connected
370. 15:34okay so they are both bound to the same
371. 15:38logical and physical
372. 15:42and functional models use the top-down
373. 15:45approach
374. 15:46during all designs so the figure here is
375. 15:49an example of
376. 15:51how a network design can be divided
377. 15:54into smaller yet related sections
378. 15:57using the structure design and processes
379. 16:03network design tools so several types of
380. 16:07tools
381. 16:08can be used to ease the task of
382. 16:10designing complex
383. 16:11modern network including the following
384. 16:14okay you've got the network modeling
385. 16:17tools
386. 16:19network modeling tools are helpful when
387. 16:21a lot of input design
388. 16:23information such as customer
389. 16:24requirements
390. 16:26network audit analysis results and
391. 16:29others
392. 16:30exist so network modeling tools
393. 16:33enable modeling of both simple and
394. 16:36complex networks
395. 16:38so the tools process the information
396. 16:41provided
397. 16:42and return a proposed configuration
398. 16:45which can be
399. 16:47modified okay so using
400. 16:52a tool available okay and the process to
401. 16:57add redundant links
402. 16:58support additional sites and so forth
403. 17:02okay so you also have strategic
404. 17:05analysis tools okay
405. 17:09strategic analysis tools or what if
406. 17:12tools
407. 17:13help designers and other people who are
408. 17:15working on the design
409. 17:17engineers technologists business and
410. 17:20marketing professionals
411. 17:21okay so to develop network and service
412. 17:24plans
413. 17:25including detailed technical and
414. 17:28business analysis so this
415. 17:31tools attempt to calculate the effects
416. 17:35of specific network components through
417. 17:38simulated scenario
418. 17:40okay you also need decision tables as
419. 17:43discussed
420. 17:44decision tables are manual tools for
421. 17:47choosing specific network
422. 17:48characteristics from multiple options
423. 17:51based on required parameters
424. 17:55right so you can also use simulation and
425. 17:59verification tools
426. 18:01okay or services these tools or services
427. 18:05are used to verify the acquired design
428. 18:08so thereby listening the
429. 18:12need for pilot network implementation
430. 18:16okay now the feature here illustrates
431. 18:20how the initial requirements information
432. 18:22is processed
433. 18:23with network design tools to produce the
434. 18:26network design
435. 18:32planning and implementation so if a plan
436. 18:35is composed of multiple complex
437. 18:37components
438. 18:38then we have to implement each component
439. 18:40separately
440. 18:42that is modularization okay do not
441. 18:45implement
442. 18:45everything at once so incremental
443. 18:49implementation is also used so
444. 18:51just like in software development we
445. 18:53have incremental
446. 18:55okay it reduces troubleshooting in case
447. 18:57of failure
448. 18:58and reduces the time needed to revert
449. 19:01to previous state in case of failure
450. 19:08the design implementation process so
451. 19:11after the design
452. 19:12is complete the design implementation
453. 19:15process
454. 19:15is executed so planning a design
455. 19:19implementation so planning and
456. 19:22documenting the design implementation is
457. 19:25the first step
458. 19:26in this process so
459. 19:30the design implementation description
460. 19:33should be detailed as possible
461. 19:37the more detailed the design
462. 19:38documentation the less nudge and
463. 19:40knowledgeable
464. 19:40the network engineer must be to
465. 19:42implement the design
466. 19:44okay so very complex implementation
467. 19:48steps
468. 19:49usually require that the designer carry
469. 19:52out
470. 19:52the implementation whereas
471. 19:56other staff okay or
472. 19:59another company can perform well
473. 20:01documented detailed implementation steps
474. 20:04okay so next would be implementation
475. 20:08must consider the possibility of failure
476. 20:12and a rollback okay or rollback plan
477. 20:16to revert to the original setup if
478. 20:19problem occurs
479. 20:21so list implementation steps
480. 20:24and estimated times in a table
481. 20:27okay so you've got the detailed
482. 20:29implementation guidelines
483. 20:31so if the design is composed of multiple
484. 20:34complex implementation steps
485. 20:36so plan to implement each step
486. 20:39separately
487. 20:40rather than all at once that's what i'm
488. 20:42saying earlier
489. 20:44in case of failure incremental
490. 20:47implementation reduces
491. 20:49troubleshooting and reduces the time
492. 20:52needed
493. 20:53to revert a previous step
494. 20:57so implementation of a network design
495. 20:59consists of several pieces
496. 21:02install hardware configure systems
497. 21:05launch into production and software so
498. 21:08each
499. 21:09phase consists of several steps
500. 21:12and the documentation for each step
501. 21:14should contain the following
502. 21:16okay that's what i'm said earlier
503. 21:18description
504. 21:19description of the steps reference
505. 21:23to the design documents you've got
506. 21:26detailed implementation guidelines
507. 21:29you've got a detailed drawback
508. 21:32guidelines
509. 21:33in case of failure and estimated time
510. 21:36for implementation
511. 21:40now the figure here illustrates a sample
512. 21:42implementation plan summary
513. 21:44so in the figure each step of the
514. 21:47implementation page is briefly described
515. 21:50with references to the detailed
516. 21:52implementation plan
517. 21:54for further details okay
518. 21:57so the detailed implementation plan
519. 21:59section should describe
520. 22:00precisely what needs to be accomplished
521. 22:05okay so there you've got the date the
522. 22:06description the implementation details
523. 22:09on your document and of course the
524. 22:11monitoring
525. 22:15now the figure here provides a detailed
526. 22:17description of an implementation step
527. 22:20it describes the configuration of
528. 22:23eigrp on 50 routers
529. 22:27okay and list the two major components
530. 22:30of the step
531. 22:32in the peer router configuration
532. 22:34procedure
533. 22:36okay now the reference of the design
534. 22:38document is useful
535. 22:41for retrieving the details about the
536. 22:43eigrp
537. 22:44implementation
538. 22:49building a prototype or a pilot network
539. 22:53so it is often desirable to verify a
540. 22:55design
541. 22:56before implementation a design can be
542. 22:59tested
543. 23:00in an existing or live network this is
544. 23:03so called
545. 23:04pilot or preferably in a prototype
546. 23:08network
547. 23:08that does not affect your existing
548. 23:10network
549. 23:12so a successful design implementation in
550. 23:14either a pilot or prototype network
551. 23:17can be used as a proof of concept in
552. 23:20preparation for
553. 23:21full implementation and can be
554. 23:24used as input to the implementation
555. 23:27steps
556. 23:28so what are the key points here okay so
557. 23:31key points
558. 23:33a pilot test or a pilot network tests
559. 23:38and verifies the design before the
560. 23:39network is
561. 23:41launched or is a subset of the existing
562. 23:43network
563. 23:44in which the design is tested okay
564. 23:48so next would be a pilot network is
565. 23:52normally used when the design
566. 23:54is for a completely new network pilots
567. 23:58can also be used
568. 23:59for designs that add to an existing
569. 24:02network
570. 24:04okay so a prototype network is usually
571. 24:09used to verify designs
572. 24:11that must be implemented on an existing
573. 24:14network infrastructure
574. 24:16so the prototype or pilot implementation
575. 24:19can have
576. 24:20one of these results it could be a
577. 24:23success
578. 24:24or a failure success
579. 24:27this result is usually enough to prove
580. 24:30the design concepts failure
581. 24:34this result is normally used to correct
582. 24:36the design
583. 24:38the prototype or pilot pace is then
584. 24:40repeated
585. 24:43in the case of small deviations the
586. 24:46design can be corrected and tested
587. 24:48in the prototype or pilot network
588. 24:52immediately
589. 24:56so the figure here is a sample topology
590. 24:59subset of
591. 25:00a plant network the highlighted areas
592. 25:04okay indicate the parts of the network
593. 25:06involved
594. 25:07in a red design this part
595. 25:10of the topology is implemented first in
596. 25:12a prototype to verify the design
597. 25:18documenting the design so a design
598. 25:22document lists
599. 25:23the design requirements documents the
600. 25:26existing network
601. 25:27and the network design identifies the
602. 25:30proof of concept strategy
603. 25:32and results and details the
604. 25:34implementation plan
605. 25:36so the final design document structure
606. 25:38should be similar to
607. 25:41this diagram here which includes the
608. 25:44following so you've got introduction
609. 25:47every design document should include an
610. 25:49introduction to present
611. 25:50the main reasons leading to the network
612. 25:54design or red design
613. 25:56you also have the design requirements
614. 25:59also a mandatory part
615. 26:00of any design document this section
616. 26:04includes the organization requirements
617. 26:07and design
618. 26:07goals that must be fulfilled
619. 26:10existing network infrastructure this
620. 26:13section is required only for
621. 26:15a network redesign the subsection
622. 26:18document the results of the existing
623. 26:21network characterization steps
624. 26:26so you also have the design okay
625. 26:30this section is an essential part of the
626. 26:33design document and identifies the
627. 26:35design
628. 26:35and implementation details the design
629. 26:38details documented will obviously differ
630. 26:42depending on the type of design project
631. 26:45so whether it is completely new network
632. 26:48a network red design
633. 26:50or simply a new service introduction
634. 26:53for example but they typically include
635. 26:56the topology
636. 26:58addressing and design implementation
637. 27:02details such as configuration templates
638. 27:05and exact configurations
639. 27:08of network devices like router switches
640. 27:11okay are included to ease the
641. 27:12implementation process
642. 27:15so you also have the proof of concepts
643. 27:18okay this section describes
644. 27:20the pilot or prototype network
645. 27:22verification
646. 27:23test results you also have the
647. 27:26implementation plan
648. 27:28this section provides an implementation
649. 27:32details
650. 27:32that technical staff need to carry
651. 27:36as quickly as possible or smoothly as
652. 27:40possible maybe
653. 27:41okay without requiring the presence of
654. 27:43the designer
655. 27:46all right and also you also have the
656. 27:48appendices
657. 27:49which usually include lists and
658. 27:52optionally configurations of existing
659. 27:54network devices
660. 27:58so to summarize the using the top-down
661. 28:02approach
662. 28:03to network design so designing an
663. 28:06enterprise network is a complex
664. 28:08project top-down design facilitates the
665. 28:12process by dividing it into smaller and
666. 28:15more manageable steps
667. 28:17decision tables facilitate the selection
668. 28:20of the most appropriate option
669. 28:23from many possibilities in assessing the
670. 28:26network
671. 28:27or the scope of network design determine
672. 28:30whether the design
673. 28:31is for a new network or is a
674. 28:34modification of the entire network
675. 28:36a single segment or module a set of
676. 28:39plans
677. 28:40a one or a remote access network
678. 28:44so the output of the design should be a
679. 28:47model of the complete system
680. 28:49so to achieve this the top down approach
681. 28:52is highly recommended
682. 28:55when the design is complete you are
683. 28:58ready to document the implementation and
684. 29:00migration
685. 29:01in as much detail as possible
686. 29:04so after a design is complete you should
687. 29:07verify it
688. 29:08you can test the design in an existing
689. 29:12or live network pilot or in a prototype
690. 29:15network that will not affect the
691. 29:17existing network
692. 29:19so a design document lists
693. 29:22the design requirements document the
694. 29:25existing network
695. 29:26documents the network design identifies
696. 29:30the proof of concept
697. 29:31strategy and details and implementation
698. 29:34plan
699. 29:37now to summarize the module
700. 29:41so the cisco sona is the enterprise
701. 29:44framework
702. 29:45for implementing intelligent networks
703. 29:47and
704. 29:48maps business requirements to network
705. 29:50requirements
706. 29:52the design methodology under ppd io
707. 29:55includes just tasks identifying customer
708. 29:58requirements
709. 30:00characterizing the existing network and
710. 30:02sites
711. 30:03designing the network topology and
712. 30:05solutions
713. 30:06the result of the network
714. 30:07characterization is a summary report
715. 30:09describing the health
716. 30:10of the network so top-down design
717. 30:14facilitates network design
718. 30:17so we come to an end of this video
719. 30:19lecture see you on the next video