1 1 00:00:00,480 --> 00:00:02,100 Ethernet issues. 2 2 00:00:02,100 --> 00:00:03,760 In this video we're going to discuss 3 3 00:00:03,760 --> 00:00:06,350 the various Ethernet issues that you may experience 4 4 00:00:06,350 --> 00:00:07,700 such as duplexing issues, 5 5 00:00:07,700 --> 00:00:09,480 and how you can troubleshoot different issues 6 6 00:00:09,480 --> 00:00:11,610 using LED status indicators. 7 7 00:00:11,610 --> 00:00:15,020 So let's talk first about those LED status indicators. 8 8 00:00:15,020 --> 00:00:17,240 These tend to be used to diagnose an issue 9 9 00:00:17,240 --> 00:00:19,810 in both fiber optic and copper connections. 10 10 00:00:19,810 --> 00:00:21,590 Most of your network interface cards 11 11 00:00:21,590 --> 00:00:23,950 are going to have two lights on the back of that card. 12 12 00:00:23,950 --> 00:00:27,110 One for an activity light and one for a link speed light. 13 13 00:00:27,110 --> 00:00:29,010 Now the activity light is going to be used to show 14 14 00:00:29,010 --> 00:00:31,280 the status of the link when it's in used. 15 15 00:00:31,280 --> 00:00:32,980 If the activity light is off 16 16 00:00:32,980 --> 00:00:34,080 that means there's no link, 17 17 00:00:34,080 --> 00:00:35,760 or connection being established. 18 18 00:00:35,760 --> 00:00:37,810 If the activity light is solid orange 19 19 00:00:37,810 --> 00:00:40,240 this indicates there's a link or a connection established 20 20 00:00:40,240 --> 00:00:41,730 with this network interface card, 21 21 00:00:41,730 --> 00:00:43,830 and the upstream device that it's connected to 22 22 00:00:43,830 --> 00:00:45,150 such as your switch. 23 23 00:00:45,150 --> 00:00:47,740 But when you start to see that light blinking orange, 24 24 00:00:47,740 --> 00:00:49,430 this indicates there's data activity 25 25 00:00:49,430 --> 00:00:51,610 occurring over that link or connection. 26 26 00:00:51,610 --> 00:00:53,910 So if you're trying to determine if the issue exists 27 27 00:00:53,910 --> 00:00:56,750 with the network interface card, or the network itself, 28 28 00:00:56,750 --> 00:00:59,250 a quick look at that activity light can be a good hint 29 29 00:00:59,250 --> 00:01:00,690 during your network troubleshooting. 30 30 00:01:00,690 --> 00:01:02,410 Because if you see an orange light, 31 31 00:01:02,410 --> 00:01:03,870 either solid or blinking, 32 32 00:01:03,870 --> 00:01:05,930 this means there's a valid connection or link 33 33 00:01:05,930 --> 00:01:08,210 between your NIC and the switch. 34 34 00:01:08,210 --> 00:01:09,840 The second light you're going to find on a NIC 35 35 00:01:09,840 --> 00:01:11,470 is the link speed light. 36 36 00:01:11,470 --> 00:01:14,550 Now the speed LED will either be off, orange, or green, 37 37 00:01:14,550 --> 00:01:15,410 depending on the speed 38 38 00:01:15,410 --> 00:01:17,560 of the network interface cards connection. 39 39 00:01:17,560 --> 00:01:20,150 If your connection is operating at one gigabit per second 40 40 00:01:20,150 --> 00:01:21,530 you're going to see a green light. 41 41 00:01:21,530 --> 00:01:23,570 If you have 100 megabit per second connection 42 42 00:01:23,570 --> 00:01:24,970 you're going to see an orange light, 43 43 00:01:24,970 --> 00:01:27,010 if it's off that's going to indicate you're operating 44 44 00:01:27,010 --> 00:01:29,740 at a slow speed of 10 megabits per second. 45 45 00:01:29,740 --> 00:01:31,280 These settings may change depending 46 46 00:01:31,280 --> 00:01:32,720 on your network interface card, 47 47 00:01:32,720 --> 00:01:35,810 but for most NICs this is a pretty accurate description. 48 48 00:01:35,810 --> 00:01:38,140 Now, these lights aren't just used with the NICs though 49 49 00:01:38,140 --> 00:01:39,710 in a workstation or server, 50 50 00:01:39,710 --> 00:01:41,600 you also are going to have your network switches 51 51 00:01:41,600 --> 00:01:44,940 having similar LEDs for each Ethernet port that they have 52 52 00:01:44,940 --> 00:01:47,350 so you can determine very quickly by looking at it 53 53 00:01:47,350 --> 00:01:51,030 the status and activity level for each port on that switch. 54 54 00:01:51,030 --> 00:01:53,190 Next, we have duplexing issues. 55 55 00:01:53,190 --> 00:01:56,840 Now the most common duplexing issue is a duplex mismatch. 56 56 00:01:56,840 --> 00:01:58,650 A duplex mismatch can occur 57 57 00:01:58,650 --> 00:02:00,450 when two ends of an Ethernet connection 58 58 00:02:00,450 --> 00:02:02,990 attempt to negotiate a full duplex connection, 59 59 00:02:02,990 --> 00:02:04,680 but one of those devices 60 60 00:02:04,680 --> 00:02:06,370 thinks the connection is full duplex, 61 61 00:02:06,370 --> 00:02:08,860 and the other one thinks it's half duplex. 62 62 00:02:08,860 --> 00:02:11,200 Now, you can identify this type of condition 63 63 00:02:11,200 --> 00:02:13,320 by observing a high rate of packet loss 64 64 00:02:13,320 --> 00:02:14,770 without the high rate of jitter 65 65 00:02:14,770 --> 00:02:17,060 that would normally be typical of congestion. 66 66 00:02:17,060 --> 00:02:19,820 Also, you're going to see a high received error rate, 67 67 00:02:19,820 --> 00:02:21,270 and runt packets showing up 68 68 00:02:21,270 --> 00:02:23,550 when you're using a duplex mismatch. 69 69 00:02:23,550 --> 00:02:25,480 Now to prevent a duplex mismatch, 70 70 00:02:25,480 --> 00:02:27,400 you should ensure both devices are configured 71 71 00:02:27,400 --> 00:02:28,820 to use auto negotiate 72 72 00:02:28,820 --> 00:02:30,680 when they're establishing their connections. 73 73 00:02:30,680 --> 00:02:33,280 If they fail to auto negotiate the connection themselves, 74 74 00:02:33,280 --> 00:02:35,440 you can manually configure them as full duplex, 75 75 00:02:35,440 --> 00:02:38,210 or half duplex depending on your network conditions. 76 76 00:02:38,210 --> 00:02:41,600 Remember, your conditions should be set to full duplex 77 77 00:02:41,600 --> 00:02:43,530 if you're using switches on your network, 78 78 00:02:43,530 --> 00:02:45,230 because each switch port is considered 79 79 00:02:45,230 --> 00:02:46,480 its own collision domain.