SRWE M16 Troubleshoot Static and Default Routes — Transcript

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1. 0:05hi hello there
2. 0:06welcome to troubleshoot static and
3. 0:08default routes
4. 0:09so this course gave you an in-depth
5. 0:12knowledge
6. 0:12and skills you need to set up switches
7. 0:15and routers including wireless devices
8. 0:18on your growing network so you really
9. 0:20are good at network administration
10. 0:24but what makes a good network
11. 0:27administrator
12. 0:28into a great one the ability to
13. 0:31effectively troubleshoot
14. 0:33the best way to gain network
15. 0:34troubleshooting skills is simple
16. 0:37always be in troubleshooting so in this
17. 0:40module
18. 0:41you will troubleshoot both static and
19. 0:43default routes
20. 0:44let's gather it
21. 0:51alright so for the module objective
22. 0:55so this is troubleshoot static and
23. 0:57default routes
24. 1:00so module objective is the troubleshoot
25. 1:03static and default route configurations
26. 1:06so some topics included are the packet
27. 1:09processing with static routes
28. 1:10so we are going to explain how a router
29. 1:13processes packets
30. 1:14when a static route is configured also
31. 1:18troubleshoot ipv4 static and default
32. 1:21cloud configuration so troubleshoot
33. 1:22common static and default route
34. 1:24configuration issues
35. 1:29okay so let's talk about the packet
36. 1:31processing with static routes
37. 1:34so before we dive into troubleshooting
38. 1:36portion of this module
39. 1:38this topic provides a brief overview
40. 1:42of how packets are forwarded in static
41. 1:44routes
42. 1:47okay now in the figure here see the
43. 1:50animation where pc1
44. 1:52is sending packet going to pc3
45. 1:55all right so if you will observe and
46. 1:57notice
47. 1:59the packets has a temporary stop
48. 2:02on each of the router okay so that means
49. 2:04it is referring to the routing table
50. 2:07okay so that is good for r1 r2 and r3
51. 2:10here
52. 2:11because when the packets gets in into
53. 2:12the router the router
54. 2:15tends to compare the destination address
55. 2:18of the packet with that of the routing
56. 2:21table entry
57. 2:23okay now the following describes the
58. 2:27packet forwarding process
59. 2:29with static routes so as demonstrated in
60. 2:31the animation earlier
61. 2:33okay so basically the packet arrives
62. 2:37on the giga ethernet 000
63. 2:41of interface r1
64. 2:45okay now r1 does not have a specific
65. 2:49route to the destination network
66. 2:52192.168.2.0 slash 24
67. 2:55which is the lan on r3
68. 2:59okay so therefore r1 uses a default
69. 3:02static route
70. 3:05so r1 encapsulates the packet in a new
71. 3:08frame
72. 3:09because r2 is a point to point
73. 3:12link and r1 adds all one's address
74. 3:16for the layer 2 destination address
75. 3:22okay now the frame is forwarded out
76. 3:25serial 010 interface
77. 3:27and the packet arrives on serial 01 0
78. 3:30interface of r2
79. 3:32okay so r2 then encapsulates the frame
80. 3:37and looks for a route to the destination
81. 3:40so take note again when the packet
82. 3:43arrives on the router
83. 3:45it has to check the destination address
84. 3:49with its routing table okay
85. 3:53so take note that r2 here has a static
86. 3:56route
87. 3:57to 192.168.2.0 out of
88. 4:00serial zero one one interface
89. 4:04okay now r2 then encapsulates the packet
90. 4:08in a new frame because the link to r3
91. 4:12is a point-to-point link so again r2
92. 4:15adds an all ones address for the layer 2
93. 4:19destination address all right
94. 4:24so the next would be the frame is
95. 4:27forwarded
96. 4:28out of serial zero one one okay
97. 4:31then the packet arrives on the serial
98. 4:34zero one one interface on r3
99. 4:37right now as the packet reaches r3
100. 4:41okay so r3 then then encapsulates the
101. 4:44frame
102. 4:45and looks for a route to the destination
103. 4:50right so in here
104. 4:55so r3 has connected route
105. 4:58to 192.168.2.0 that's 24 out
106. 5:01of the gigabit ethernet serial 0
107. 5:040 or gigabit gigabit ethernet
108. 5:07serial 0 0 interface so which is this
109. 5:10one here
110. 5:12all right now the next thing that will
111. 5:16happen is
112. 5:17r3 looks up the arp
113. 5:20table entry for one into one sixty to
114. 5:22the ten
115. 5:23to find the layer 2 mac address control
116. 5:26or mac address
117. 5:27for pc3 alright
118. 5:30so if no entry exists
119. 5:34r3 sends an
120. 5:37arp or address resolution protocol
121. 5:39request
122. 5:40out of the gigabit ethernet 0 0 0
123. 5:43interface
124. 5:45and pc3 responds with an arp reply
125. 5:49which includes the pc3 mac address
126. 5:53okay so r3 then encapsulates
127. 5:56the packet in a new frame with a mac
128. 5:59address
129. 6:00of the gigabit internet 0.0 interface
130. 6:03as the source layer to address and the
131. 6:07mac address of pc3
132. 6:09as the destination mac address so the
133. 6:12frame is forwarded out
134. 6:14gigabit ethernet 0 0
135. 6:170 interface so the packet arrives on the
136. 6:21nic
137. 6:22or the network interface card of pc3
138. 6:26okay so i would recommend seeing the
139. 6:30video demo
140. 6:30regarding this one okay and you can see
141. 6:34there that as i use the
142. 6:37simulation okay so you'll see
143. 6:40some of the activities that i am
144. 6:42referring to on this discussion
145. 6:47all right so the next one would be
146. 6:48troubleshoot ipv4 static and default
147. 6:51route configuration
148. 7:00all right so next would be
149. 7:03troubleshooting ipv4 static and default
150. 7:05route configuration
151. 7:07okay so no matter how
152. 7:10how well you set up your network you
153. 7:13will have to be ready to troubleshoot
154. 7:15some problem
155. 7:16so networks are frequently subject to
156. 7:19events
157. 7:20that can cause their status to change so
158. 7:23we call it network changes
159. 7:25okay so for example an interface can
160. 7:29fail
161. 7:31or a service provider drops a connection
162. 7:35or it could be links can become
163. 7:38oversaturated
164. 7:40and an administrator may enter a wrong
165. 7:43configuration
166. 7:46so when there is a change in the network
167. 7:49connectivity may lost
168. 7:51so network administrators are
169. 7:53responsible for
170. 7:54pinpointing and solving the problem so
171. 7:58to find and solve these
172. 7:59issues so network administrator must be
173. 8:02familiar
174. 8:03with tools to help isolate routing
175. 8:05problems quickly
176. 8:08okay now i have here lists of commands
177. 8:12that you can use to troubleshoot static
178. 8:15and default route configuration
179. 8:17basically this applies to all of the
180. 8:20routing protocols
181. 8:22but since our topic here is static in
182. 8:23the cultural
183. 8:25so we are going to focus on that okay
184. 8:29so these commands includes ping
185. 8:33trace route or tracer if you use it on a
186. 8:35pc
187. 8:37okay show ip route show ip interface
188. 8:40brief
189. 8:41and show cdp neighbors so let's get into
190. 8:45the details of each of the following
191. 8:47commands
192. 8:49so let's start with ping now assuming
193. 8:51that you are given this topology here
194. 8:53so this is the topology that we used on
195. 8:55the demonstration
196. 8:56and this is the same topology that we're
197. 8:58going to use
198. 9:00on troubleshooting default and static
199. 9:03routes
200. 9:04right so we have here three routers okay
201. 9:07and we have one seventy two sixteen
202. 9:10three that zero that's twenty four
203. 9:11do that zero and then one that's zero
204. 9:13and then you'll have here
205. 9:15between r2 and r3 one nine two one six
206. 9:18eight one that zero slash 24
207. 9:20and the r3 lan which is one into one six
208. 9:22eight two that zero is last 24.
209. 9:25now assuming that we are going to
210. 9:26troubleshoot okay and this topology has
211. 9:29a problem
212. 9:30so how are we going to go with the
213. 9:32troubleshooting process
214. 9:35okay so the very first thing to do is of
215. 9:37course
216. 9:38we use the pin command so ping command
217. 9:41verify layer 2 connectivity to
218. 9:43destination
219. 9:44so extended pings provide additional
220. 9:47options
221. 9:49so in this example okay
222. 9:52it displays the result of an extended
223. 9:54ping
224. 9:56from the source of r1 lan okay
225. 10:00so this is the source here the g00
226. 10:04okay to the interface of
227. 10:07r3 which is 192.168.2.1 here
228. 10:13okay so an extended ping is an enhanced
229. 10:16version of the ping utility
230. 10:18so extended ping enables you to specify
231. 10:20the source ip address
232. 10:22for the ping packets but then take note
233. 10:25that when you use this command in packet
234. 10:27tracer
235. 10:27it's not supported okay so you can use
236. 10:31the extended ping
237. 10:33on this format okay
238. 10:36or syntax only in the actual
239. 10:39configuration okay now the purpose of
240. 10:43this command is basically we are going
241. 10:44to ping
242. 10:47192.168.2.1 which is this one here
243. 10:50okay so let me use my pointer
244. 10:53or pen okay so this would be our target
245. 10:56we are going to ping this ip address
246. 11:00192.168.2.1
247. 11:01and the source would be this one
248. 11:05so this would be our source of the ping
249. 11:08and this would be the destination of the
250. 11:10pic
251. 11:11okay so in the actual configuration you
252. 11:14type in
253. 11:15on r1 ping 192.168.2.1 which is the
254. 11:20destination
255. 11:21and the ping would be coming from g000
256. 11:26or 16 3.1
257. 11:30and it says successful
258. 11:33right so that means we have connectivity
259. 11:36from r1 lan going to the r3 lan
260. 11:41all right so that's the ping utility
261. 11:43command
262. 11:47okay so the next command would be
263. 11:49traceroute trace route
264. 11:51is a command used in a router so if
265. 11:53you're going to use this in a pc
266. 11:55so the command is tracer all right
267. 11:58so the trace route verify path
268. 12:01to destination network so it uses icmpx
269. 12:05or reply message
270. 12:07to determine the hubs to the destination
271. 12:10okay now this example displays the
272. 12:13result of a traceroute
273. 12:15from r1 again this is our source here
274. 12:18okay
275. 12:18so to the r3 lan destination
276. 12:22okay now note that each hub
277. 12:25route returns an icmp reply
278. 12:29okay now if you are going to evaluate
279. 12:31the output here
280. 12:33okay so r1 trace it out 192.168.2.1 so
281. 12:36we are going to trace
282. 12:39the movement of the packet and the
283. 12:41connectivity from
284. 12:42r1 going to r3 so we are expecting
285. 12:45that the first half output here
286. 12:49would be this one here
287. 12:52this is your first half here okay so
288. 12:55172 16 to the two which is
289. 12:59this interface here of r2 now to reach
290. 13:03192.168.2.1 here so the next half would
291. 13:06be
292. 13:07this one okay
293. 13:11and that is one into one six eight one
294. 13:13that one
295. 13:15so that means to reach one into one six
296. 13:17eight to that one
297. 13:19we have two hubs to get into the
298. 13:21destination
299. 13:22and that is the output of the traceroute
300. 13:24so it allows you
301. 13:26okay to observe where the packet goes
302. 13:29down
303. 13:29now in this case it was able to reach
304. 13:31the destination all right
305. 13:36so that's trace route command you can do
306. 13:39the same
307. 13:39in a pc and the command is again tracer
308. 13:43all right so you've got research here
309. 13:48and then followed by your target ip
310. 13:51address
311. 13:53so that would be coming from a pc
312. 13:59all right so the next command that you
313. 14:01can use to troubleshoot is
314. 14:04show ip route okay so
315. 14:07basically the command show iprout will
316. 14:10display the routing table
317. 14:12so it is used to verify route entries
318. 14:14for destination ip addresses
319. 14:17so the content of the routing table is
320. 14:19basically
321. 14:20the destination okay or the destination
322. 14:24network
323. 14:25now for instance we have that command
324. 14:28show ip route
325. 14:29okay so begin gateway this is optional
326. 14:32you could have simply show up
327. 14:34all right so show ipad out so take note
328. 14:37that
329. 14:38it listed three ss here so we are on r1
330. 14:41here
331. 14:42okay and the s stands for static routes
332. 14:45right
333. 14:46so we have three asses so the first s
334. 14:49would be
335. 14:50one seventy two sixteen one that zero
336. 14:51here so this is the first s here
337. 14:54let's denote this as s1 right
338. 14:58this is a remote network from
339. 15:01r1 so the next s would be 192.168.1.04
340. 15:08and this is the second s that we have
341. 15:11on the routing table let's denote this
342. 15:13as s2 here
343. 15:15okay and the third s is of course
344. 15:19192.168.2.0
345. 15:21which is this one here so basically
346. 15:25the routing table displays the
347. 15:27destination network
348. 15:28okay so aside of course from directly
349. 15:30connected networks that we have there
350. 15:33okay so you can use this command
351. 15:36to troubleshoot and look if the
352. 15:39destination packet
353. 15:40ip address is within the routing table
354. 15:44entry
355. 15:46all right so to reach all of this
356. 15:49okay so it has been configured with the
357. 15:52next hub ip address
358. 15:54all right so that means to reach s1 s2
359. 15:57and
360. 15:57s3 here we have to pass through 170 to
361. 16:0116
362. 16:02to that to here which is via serial 0 1
363. 16:050 for 2.
364. 16:08okay so in using the show ip route
365. 16:13just make sure if you are using the
366. 16:15standard uh
367. 16:16static configuration the number of ss
368. 16:19corresponds to the number of remote
369. 16:21networks
370. 16:22all right or indirectly connected
371. 16:24networks to r1 here
372. 16:30okay so the next troubleshooting command
373. 16:32is so ip interface brief
374. 16:34so what it does it displays the status
375. 16:37of devices interfaces
376. 16:39so it is used to verify the operational
377. 16:42status and ip address of an interface so
378. 16:44this is also a very useful command here
379. 16:47okay so and i use these commands
380. 16:51okay so in troubleshooting so
381. 16:54again if we are on r1 here
382. 16:58and then we should show ip interface
383. 17:00proof command so basically this will
384. 17:02display all the interfaces
385. 17:04on r1 okay so both active or unassigned
386. 17:08and assigned
387. 17:09right now in this case we have here
388. 17:12gigabit ethernet
389. 17:13000 okay so which
390. 17:16is this interface here you've got serial
391. 17:200 1
392. 17:200 which is uh this interface here
393. 17:24and you have the ip address assigned to
394. 17:27it so you could check also
395. 17:29the ip assignment on the interface via
396. 17:31show app interface brief
397. 17:33okay so the good thing also about this
398. 17:36command is you could check the status of
399. 17:38the interfaces here
400. 17:40and the status is all up now if it is
401. 17:42down then you need to troubleshoot
402. 17:44okay you need to start troubleshooting
403. 17:46from there
404. 17:47right
405. 17:52okay so next command would be show cdp
406. 17:54neighbors
407. 17:56so the show cdp neighbor command
408. 17:58provides a list of directly connected
409. 18:00cisco devices
410. 18:02so this commands validates layer 2
411. 18:06okay and therefore layer 1 connectivity
412. 18:08so for example
413. 18:09if a neighbor device is listed
414. 18:13in the command output here but it cannot
415. 18:15be pinged
416. 18:16the layer 3 addressing table should be
417. 18:18investigated
418. 18:19okay so again we are on r1 here
419. 18:23and we issue the command show cdp
420. 18:26neighbor so basically
421. 18:28this will show us okay so r2
422. 18:31and r3 here which are the neighbors of
423. 18:34r1
424. 18:36okay so you can also see the local
425. 18:38interface where it is connected to
426. 18:40okay the whole time the capability all
427. 18:43right capability
428. 18:44s is for switch and r is for router here
429. 18:49okay and then you also have the platform
430. 18:50and then the port and that information
431. 18:53all right so you can use this command
432. 18:55show cdp neighbor
433. 18:57as a tool in troubleshooting
434. 19:00static and default route configuration
435. 19:07all right so let's solve a connectivity
436. 19:10problem
437. 19:11so finding a missing or misconfigured
438. 19:13route is a relatively straightforward
439. 19:15process
440. 19:16if the right tools are used in a
441. 19:19methodical
442. 19:20manner right so for instance
443. 19:23the user at pc1 all right
444. 19:27so reports that he cannot access
445. 19:31resources on the r3 lab so assuming that
446. 19:34that's our problem here
447. 19:35so we cannot access this destination
448. 19:38from the source
449. 19:40all right now this can be confirmed by
450. 19:44pinging the lan interface of r3
451. 19:47using the lan interface of r1 as the
452. 19:50source
453. 19:51okay so again we will use the topology
454. 19:55that we used in the demonstration in the
455. 19:57previous discussion
456. 19:59okay so to demonstrate how to
457. 20:00troubleshoot this connectivity problem
458. 20:03all right
459. 20:09okay so the very first thing that we
460. 20:10need to do is to ping the remote plan
461. 20:12so as mentioned earlier now the network
462. 20:16administrator
463. 20:17can test connectivity between two lands
464. 20:20from
465. 20:20r1 instead of pc1 okay but then
466. 20:23of course you can use a ping command
467. 20:26from pc1 to ping your
468. 20:27pc3 we call it end to end connectivity
469. 20:30test but
470. 20:31you can also use this r1 here okay if
471. 20:34you can reach
472. 20:35this uh default gateway of pc3 which
473. 20:39is the r3 lamp
474. 20:45all right so this can be done by
475. 20:48sourcing the ping
476. 20:49from the g00
477. 20:520 interface of r1 okay
478. 20:56to the g00 interface of r3 so this would
479. 20:59be our source and this would be our
480. 21:00target or destination
481. 21:02here so the ping results shows that
482. 21:04there is no connectivity
483. 21:06between these lands okay so as you can
484. 21:09see here
485. 21:11so on r1 we ping 192.162.1 which is this
486. 21:14interface serial or
487. 21:16g000 of r3 which is the r3 lan
488. 21:20and we source it out from g000 here
489. 21:24and if you will observe success rate is
490. 21:260 so you've got 0 over 5 there
491. 21:29so it's not connected or there is no
492. 21:32connectivity between these two networks
493. 21:34all right so the next thing is
494. 21:38since you cannot ping okay
495. 21:41r1 to r3 lan all right so you cannot
496. 21:44ping from the source to destination
497. 21:47so the next thing to do is all right so
498. 21:50there is no
499. 21:51ping connectivity there so the next
500. 21:53thing to do is
501. 21:54to ping the next hub router okay so
502. 21:58ping the serial 0 1 0
503. 22:01on r2 okay so that's the next thing you
504. 22:04need to do
505. 22:05and then this thing is sourced from
506. 22:08serial 0 1 0
507. 22:09interface of r1 okay so therefore the
508. 22:12issue is not
509. 22:13loss of connectivity between r1 and r2
510. 22:16because when we ping it
511. 22:18we have a 100 percent success rate
512. 22:22okay so this are directly connected
513. 22:24networks and we are expecting
514. 22:26that when we establish a ping command in
515. 22:28here it should be successful
516. 22:30so if it is not then you have to
517. 22:31troubleshoot your connectivity here
518. 22:34so you check the ip address if they
519. 22:36belong to the same
520. 22:37network so in that case when we
521. 22:41when we issue the command ping 172 162.2
522. 22:45here on r1
523. 22:46so we have a connectivity so this one is
524. 22:49checked here
525. 22:50all right but then our problem again is
526. 22:54we cannot
527. 22:55reach the destination
528. 22:58so next so ping the r3 lan
529. 23:02from serial zero one zero
530. 23:05okay so i ping from r1 to the r2
531. 23:08interface
532. 23:10192.168.2.1 is successful as well
533. 23:14okay so on r1 okay so ping 192.168.2.1
534. 23:21so take note that we did not specify
535. 23:24the source here okay so the ping is
536. 23:27sourced
537. 23:28from serial zero one zero
538. 23:32so if you did not specify the source it
539. 23:34always sourced on the
540. 23:36exit interface okay
541. 23:39now r3 has a route back
542. 23:43to the network between r1 and r2
543. 23:47170 to 16 to 2.0 slash 24.
544. 23:52okay so take note that this is okay
545. 23:54after our testing
546. 23:56on the previous slide so this confirms
547. 23:59that r1 can reach
548. 24:00the remote lan on r3 however
549. 24:04the packet's source from the lan on r1
550. 24:07cannot okay so this indicates that
551. 24:11either
552. 24:12r2 here or r3
553. 24:15may have an incorrect or missing route
554. 24:19to lan on r1
555. 24:22okay so again take note that we can
556. 24:25ping from r1 192.168 to that one
557. 24:30we can ping this okay this is the
558. 24:32destination or our target here
559. 24:34and we source it from serial zero one
560. 24:38zero so that means
561. 24:39we can have a connectivity going to this
562. 24:42but when we source it out from g g000
563. 24:46there is no connectivity going to the
564. 24:48destination
565. 24:49all right so that's our problem okay
566. 24:55so the next thing to do is verify the r2
567. 24:58routing table
568. 25:00okay so we issue the show ipad out
569. 25:02command
570. 25:03on r2 okay and in here
571. 25:08we have to investigate the routing
572. 25:09tables for r2 and r3
573. 25:12so the routing table for r2 is shown
574. 25:14here
575. 25:15notice that 172 16
576. 25:193.0 slash 24
577. 25:23is using the next hop ip address 1 into
578. 25:26168
579. 25:271.1 okay so this is incorrect
580. 25:30so the static route to 172 16 3.0
581. 25:35network has been configured using
582. 25:38the next top ip address of 192.168.1.1
583. 25:42so therefore packets distinct
584. 25:45to 3.0 okay
585. 25:49or the r1 lan will be sent back to
586. 25:52r3 instead of r1 okay
587. 25:56so if there will be packet going to 170
588. 25:59to 16
589. 26:003.0 here for instance we have a packet
590. 26:03here
591. 26:04which is distinct to this network
592. 26:08but because of the configuration okay it
593. 26:10will be forwarded back
594. 26:12to 192.168.1.1 which is
595. 26:16here all right so this is 192.168.1.1
596. 26:22all right so that's an error there so
597. 26:24what are we going to do next
598. 26:28so we need to correct the r2 static
599. 26:31route configuration
600. 26:33so we have to run configuration
601. 26:37okay so show run or show running config
602. 26:40okay so include ipad out here or you
603. 26:43could simply type in show run and then
604. 26:45look for this configuration
605. 26:48all right so take note that we have an
606. 26:51incorrect ip route statement
607. 26:54so the incorrect ipad out statement is
608. 26:56removed
609. 26:57and the correct route is entered okay
610. 27:01so this is our
611. 27:04incorrect statement so take note that to
612. 27:07reach 170 to 16 3.0 here
613. 27:11okay on r2 the next half ip address
614. 27:14should be this
615. 27:15which is 172 16 2.1
616. 27:18so we are going to correct it with 172
617. 27:2216 to that one so we need to remove this
618. 27:24now to remove this okay so the command
619. 27:27is
620. 27:28no ip route okay so you copy the enter
621. 27:31statement there
622. 27:32and then 170 to 163.0
623. 27:37255.255.255.0 and then 192.168.1
624. 27:40and then type in the correct
625. 27:43um command which is ipad out 172 163.00
626. 27:48255 255 255.00 now using the correct
627. 27:52nextup ip address all right
628. 27:58so the next thing is we need to verify
629. 28:00the new static route
630. 28:02is installed so earlier on okay so take
631. 28:05note that
632. 28:08this next hub ip address was set earlier
633. 28:10to 192.168.1.1
634. 28:12now we have set it correctly
635. 28:16to 172 16 to that one
636. 28:19all right and we are expecting of course
637. 28:22the next would be
638. 28:23a successful connectivity so we go back
639. 28:26to our problem earlier
640. 28:27which is ping the remote line again okay
641. 28:30so this time
642. 28:31so we ping 192 168
643. 28:342.1 again this is our destination
644. 28:38and we want to source it out on this
645. 28:41so that is ping 192.1682. 192.168.2.1
646. 28:44source
647. 28:45g000 or source
648. 28:50172.16.3.1 again
649. 28:52this type of extended ping command is
650. 28:55not supported in packet tracer
651. 28:58all right
652. 29:02all right so that's the end of this
653. 29:05video lecture so thank you very much for
654. 29:07watching and listening have a great day
655. 29:13[Music]