1 00:00:00,900 --> 00:00:09,450 So here are my two routers, let's have a look at the logging levels, show logging on router 1, there's the 2 00:00:09,450 --> 00:00:11,250 command, console 3 00:00:11,250 --> 00:00:14,970 logging by default has enabled the level is debugging. 4 00:00:16,790 --> 00:00:19,740 Other places where you can log are on the monitor. 5 00:00:20,210 --> 00:00:28,880 That's typically when you telnet to a device buffer at the moment, the buffer logging is disabled. 6 00:00:31,500 --> 00:00:38,010 Trap logging, which is used with the log server is set to the informational level, so notice console 7 00:00:38,010 --> 00:00:39,150 is debugging level. 8 00:00:40,420 --> 00:00:49,510 That's a level 7 trap logging is set by default on this router to informational, which is level 9 00:00:49,510 --> 00:00:50,020 six. 10 00:00:50,930 --> 00:00:53,180 So router 2 show logging 11 00:00:55,240 --> 00:00:56,950 or show logging, rather. 12 00:00:58,570 --> 00:01:00,830 Now, this router hasn't been changed 13 00:01:00,850 --> 00:01:10,570 this is the defaults, so console is level 7, monitor is level 7 buffer is disabled and trap. 14 00:01:11,020 --> 00:01:14,710 In other words, sending to syslog is set to informational. 15 00:01:15,750 --> 00:01:24,750 So let's see what happens when we make some changes on the routers. I'll configure an IP address on each 16 00:01:24,750 --> 00:01:25,590 router. 17 00:01:27,550 --> 00:01:29,430 So, no, shut the interface. 18 00:01:29,470 --> 00:01:33,240 Notice what happens when I type when the interface comes up. 19 00:01:33,730 --> 00:01:36,940 In this case, the text is recopied 20 00:01:38,460 --> 00:01:46,500 but on most routers by default, it will not be recopied. The reason it's done here is because, I'm 21 00:01:46,500 --> 00:01:49,800 running this router within GNS3 and, 22 00:01:52,960 --> 00:02:00,820 and by default on this GNS3 router, this command logging synchronoss was typed on the console. 23 00:02:01,570 --> 00:02:03,160 So if I typed do show run 24 00:02:04,290 --> 00:02:05,970 and have a look at the console 25 00:02:07,110 --> 00:02:08,220 of this router. 26 00:02:09,259 --> 00:02:14,720 What you'll notice is that logging Synchronoss has been enabled, which means when I'm typing a command, 27 00:02:14,720 --> 00:02:21,620 I'm not interrupted and I'll just demonstrate that again, if I type interface loopback 0 and then 28 00:02:21,620 --> 00:02:23,280 start typing the IP address. 29 00:02:23,810 --> 00:02:26,630 Notice the command is retyped 30 00:02:29,290 --> 00:02:30,310 on the console. 31 00:02:31,940 --> 00:02:38,090 However, if I go into the console of this router and type no logging Synchronoss 32 00:02:40,260 --> 00:02:44,730 and then type interface loopback 0 and start typing. 33 00:02:45,710 --> 00:02:54,620 Notice my text is not recopied, it's stuck up there, so I need to press tab as an example to see what 34 00:02:54,620 --> 00:02:55,340 I was typing. 35 00:02:56,670 --> 00:02:59,850 So generally, you're going to want to type 36 00:03:01,090 --> 00:03:06,550 logging Synchronoss on your console so that your text is recopied. 37 00:03:08,810 --> 00:03:12,970 I'll enable OSPF on these routers 38 00:03:14,590 --> 00:03:15,720 in area 0 39 00:03:19,110 --> 00:03:20,190 just to make it simple. 40 00:03:21,680 --> 00:03:25,130 I'll enable OSPF on all interfaces. 41 00:03:29,070 --> 00:03:34,470 Just before I enable it on the other router, I'm going to enable OSPF adjacencies 42 00:03:40,120 --> 00:03:42,880 and hit enter on the right hand side router. 43 00:03:45,510 --> 00:03:51,750 Notice on the left hand side router, I'm getting a lot of output on the interface because I've enabled 44 00:03:52,350 --> 00:04:00,030 debugging on router 2 I'm not getting any output because I haven't enabled debugging. 45 00:04:04,870 --> 00:04:08,050 So on router 1 I'm seeing a lot of information, so show 46 00:04:11,190 --> 00:04:16,769 IP OSPF neighbors an example shows me my neighbor relationship. 47 00:04:18,560 --> 00:04:27,080 On router 2 I just got a level 5 notification saying that the neighbor relationship came up. 48 00:04:28,640 --> 00:04:36,290 So level 5 is a notice, which is normal, but significant conditions, so I was informed that a 49 00:04:36,290 --> 00:04:42,710 neighbor relationship came up but nothing else was displayed. Whereas on router 1 because I enabled 50 00:04:43,100 --> 00:04:45,080 I was adjacency debugging. 51 00:04:45,440 --> 00:04:51,380 I'm seeing a lot of output on the console of this router 52 00:04:52,820 --> 00:05:01,750 and the reason it displays on the console is that I have a debugging level of logging on the console. 53 00:05:02,240 --> 00:05:05,000 So when you enable debugging, you see the output. 54 00:05:06,190 --> 00:05:13,080 Let's do the test again, so on the interface, I'll shut first Ethernet 00 on router 2. 55 00:05:13,810 --> 00:05:21,580 So I see logging information that the adjacency went down, level 5 `interface went down level 5 56 00:05:21,580 --> 00:05:22,180 message. 57 00:05:23,510 --> 00:05:30,170 Line protocol has gone down level 5 message when I no shut the interface again 58 00:05:31,130 --> 00:05:34,760 notice I see a lot of OSPF output on router 1 59 00:05:36,230 --> 00:05:39,800 and once again, that's because I enabled debugging. 60 00:05:41,180 --> 00:05:42,680 So if I type, show debug 61 00:05:43,900 --> 00:05:52,660 you can see that OSPF adjacency debugging has been enabled and the level of logging is set at level 62 00:05:52,660 --> 00:05:53,080 7. 63 00:05:54,390 --> 00:05:58,110 If I, however, changed the logging on 64 00:05:59,880 --> 00:06:01,140 the console 65 00:06:02,940 --> 00:06:10,230 to level 3, level 3 is error conditions as an example. What would happen now 66 00:06:12,340 --> 00:06:17,320 when I do the same test? So I've shut the interface on router 2 67 00:06:18,330 --> 00:06:19,320 I'll no shut it. 68 00:06:20,550 --> 00:06:23,100 On router 1 show debug 69 00:06:24,370 --> 00:06:30,880 I'm still running the OSPF debugging, but notice I'm not seeing debug messages on the console. 70 00:06:32,930 --> 00:06:41,420 Show IP OSPF Neighbor shows me that my neighbor relationship has come up and I can see that on router 2 71 00:06:42,410 --> 00:06:43,790 which is still using 72 00:06:46,460 --> 00:06:55,460 level 7 debugging on the console, but I don't see that on router 1 because I've changed the debbuging 73 00:06:55,610 --> 00:06:56,540 to level 3, 74 00:06:56,750 --> 00:06:58,040 in other words, errors. 75 00:06:59,040 --> 00:07:01,860 I could once again change that to 76 00:07:03,950 --> 00:07:07,280 level 7 and let's use a word, so debugging. 77 00:07:08,880 --> 00:07:09,780 One last test, 78 00:07:11,480 --> 00:07:16,730 shut the interface relationship is torn down, bring the interface up again 79 00:07:17,750 --> 00:07:24,830 and notice, once again, I see the debugging on router 1 because I've changed to the logging level 80 00:07:24,830 --> 00:07:25,730 to level 7.