1 00:00:00,210 --> 00:00:01,080 In this video, 2 00:00:01,080 --> 00:00:03,090 we're going to discuss the various ethernet issues 3 00:00:03,090 --> 00:00:04,440 that you may experience, 4 00:00:04,440 --> 00:00:05,790 such as duplexing issues 5 00:00:05,790 --> 00:00:07,560 and how you can troubleshoot different issues 6 00:00:07,560 --> 00:00:09,690 using LED status indicators. 7 00:00:09,690 --> 00:00:13,110 So let's talk first about those LED status indicators. 8 00:00:13,110 --> 00:00:15,330 These tend to be used to diagnose an issue 9 00:00:15,330 --> 00:00:17,910 in both fiber optic and copper connections. 10 00:00:17,910 --> 00:00:19,650 Most of your network interface cards 11 00:00:19,650 --> 00:00:22,050 are going to have two lights on the back of that card, 12 00:00:22,050 --> 00:00:23,370 one for an activity light 13 00:00:23,370 --> 00:00:25,200 and one for a link speed light. 14 00:00:25,200 --> 00:00:26,880 Now, the activity light is going to be used 15 00:00:26,880 --> 00:00:29,400 to show the status of the link when it's in use. 16 00:00:29,400 --> 00:00:30,596 If the activity light is off, 17 00:00:30,596 --> 00:00:33,840 that means there's no link or connection being established. 18 00:00:33,840 --> 00:00:35,910 If the activity light is solid orange, 19 00:00:35,910 --> 00:00:38,310 this indicates there's a link or a connection established 20 00:00:38,310 --> 00:00:39,930 with this network interface card 21 00:00:39,930 --> 00:00:41,910 and the upstream device that it's connected to, 22 00:00:41,910 --> 00:00:43,260 such as your switch. 23 00:00:43,260 --> 00:00:45,840 But when you start to see that light blinking orange, 24 00:00:45,840 --> 00:00:47,940 this indicates there's data activity occurring 25 00:00:47,940 --> 00:00:49,680 over that link or connection. 26 00:00:49,680 --> 00:00:51,240 So if you're trying to determine 27 00:00:51,240 --> 00:00:53,460 if the issue exists with the network interface card 28 00:00:53,460 --> 00:00:54,870 or the network itself, 29 00:00:54,870 --> 00:00:56,460 a quick look at that activity light 30 00:00:56,460 --> 00:00:58,800 can be a good hint during your network troubleshooting. 31 00:00:58,800 --> 00:01:00,480 Because if you see an orange light, 32 00:01:00,480 --> 00:01:01,980 either solid or blinking, 33 00:01:01,980 --> 00:01:03,420 this means there's a valid connection 34 00:01:03,420 --> 00:01:06,330 or link between your NIC and the switch. 35 00:01:06,330 --> 00:01:07,920 The second light you're going to find on a NIC 36 00:01:07,920 --> 00:01:09,570 is the link speed light. 37 00:01:09,570 --> 00:01:12,120 Now the speed LED will either be off, orange 38 00:01:12,120 --> 00:01:13,500 or green, depending on the speed 39 00:01:13,500 --> 00:01:15,660 of the network interface cards connection. 40 00:01:15,660 --> 00:01:18,240 If your connection is operating at one gigabit per second, 41 00:01:18,240 --> 00:01:19,620 you're going to see a green light. 42 00:01:19,620 --> 00:01:21,660 If you have a hundred megabit per second connection, 43 00:01:21,660 --> 00:01:23,040 you're going to see an orange light. 44 00:01:23,040 --> 00:01:25,110 If it's off, that's going to indicate you're operating 45 00:01:25,110 --> 00:01:27,840 at the slow speed of 10 megabits per second. 46 00:01:27,840 --> 00:01:29,040 These settings may change 47 00:01:29,040 --> 00:01:31,890 depending on your network interface card, but for most NICs, 48 00:01:31,890 --> 00:01:33,900 this is a pretty accurate description. 49 00:01:33,900 --> 00:01:36,240 Now, these lights aren't just used with the NICs though, 50 00:01:36,240 --> 00:01:37,800 in a workstation or server. 51 00:01:37,800 --> 00:01:40,440 You also are going to have your network switches having similar 52 00:01:40,440 --> 00:01:42,743 LEDs for each ethernet port that they have. 53 00:01:42,743 --> 00:01:45,420 So you can determine very quickly by looking at it, 54 00:01:45,420 --> 00:01:49,140 the status and activity level for each port on that switch. 55 00:01:49,140 --> 00:01:51,270 Next, we have duplexing issues. 56 00:01:51,270 --> 00:01:54,930 Now, the most common duplexing issue is a duplex mismatch. 57 00:01:54,930 --> 00:01:57,024 A duplex mismatch can occur with two ends 58 00:01:57,024 --> 00:01:58,890 of an ethernet connection attempt 59 00:01:58,890 --> 00:02:01,080 to negotiate a full duplex connection. 60 00:02:01,080 --> 00:02:03,188 But one of those devices thinks the connection 61 00:02:03,188 --> 00:02:06,960 is full duplex and the other one thinks it's half duplex. 62 00:02:06,960 --> 00:02:08,764 Now, you can identify this type of condition 63 00:02:08,764 --> 00:02:10,410 by observing a high rate 64 00:02:10,410 --> 00:02:12,840 of packet loss without the high rate of jitter 65 00:02:12,840 --> 00:02:15,150 that would normally be typical of congestion. 66 00:02:15,150 --> 00:02:17,940 Also, you're going to see a high receive error rate 67 00:02:17,940 --> 00:02:19,350 and rug packets showing up 68 00:02:19,350 --> 00:02:21,630 when you're using a duplex mismatch. 69 00:02:21,630 --> 00:02:23,144 Now to prevent a duplex mismatch, 70 00:02:23,144 --> 00:02:25,500 you should ensure both devices are configured 71 00:02:25,500 --> 00:02:27,210 to use auto negotiate when they're 72 00:02:27,210 --> 00:02:28,800 establishing their connections. 73 00:02:28,800 --> 00:02:31,380 If they fail to auto negotiate the connection themselves, 74 00:02:31,380 --> 00:02:33,168 you can manually configure them as full duplex 75 00:02:33,168 --> 00:02:36,330 or half duplex, depending on your network conditions. 76 00:02:36,330 --> 00:02:38,610 Remember, your conditions should be set 77 00:02:38,610 --> 00:02:41,640 to full duplex if you're using switches on your network 78 00:02:41,640 --> 00:02:42,720 because each switch port 79 00:02:42,720 --> 00:02:44,670 is considered its own collision domain.