1 00:00:00,600 --> 00:00:03,570 Why do we need quality of service, or QoS? 2 00:00:03,570 --> 00:00:06,540 Well, nowadays, we operate converged networks, 3 00:00:06,540 --> 00:00:09,390 which means all of our networks are carrying voice, data, 4 00:00:09,390 --> 00:00:11,970 and video content over the same wire. 5 00:00:11,970 --> 00:00:14,280 We don't have them all separated out, like we used to. 6 00:00:14,280 --> 00:00:15,840 We used to have networks for phones 7 00:00:15,840 --> 00:00:18,060 and one's for data and one's for video. 8 00:00:18,060 --> 00:00:21,870 But now, everything's riding over the same IP networks. 9 00:00:21,870 --> 00:00:24,660 So because of this convergence of mediums, 10 00:00:24,660 --> 00:00:25,680 we have these networks 11 00:00:25,680 --> 00:00:27,990 that now have a high level of availability 12 00:00:27,990 --> 00:00:29,310 to ensure proper delivery 13 00:00:29,310 --> 00:00:31,230 over all of these different mediums 14 00:00:31,230 --> 00:00:32,460 because we want a phone to work 15 00:00:32,460 --> 00:00:34,440 every time we pick up the phone, right? 16 00:00:34,440 --> 00:00:37,470 Well, by using QoS, we can optimize our network 17 00:00:37,470 --> 00:00:40,530 to efficiently utilize all the bandwidth at the right time 18 00:00:40,530 --> 00:00:42,450 to deliver the right service to our users 19 00:00:42,450 --> 00:00:45,060 and give us success and cost savings. 20 00:00:45,060 --> 00:00:47,280 Now, we want to have an excellent quality of service, 21 00:00:47,280 --> 00:00:49,110 an excellent service for our customers, 22 00:00:49,110 --> 00:00:52,170 and that's what we're going to start doing by using QoS. 23 00:00:52,170 --> 00:00:54,630 So what exactly is QoS? 24 00:00:54,630 --> 00:00:56,430 Well, Quality of Service enables us 25 00:00:56,430 --> 00:00:59,070 to strategically optimize our network performance 26 00:00:59,070 --> 00:01:01,080 based on different types of traffic. 27 00:01:01,080 --> 00:01:02,970 Previously, we talked about the fact 28 00:01:02,970 --> 00:01:05,580 that we want to categorize our different traffic types. 29 00:01:05,580 --> 00:01:07,890 I might have web traffic and voice traffic 30 00:01:07,890 --> 00:01:10,230 and video traffic and email traffic. 31 00:01:10,230 --> 00:01:11,370 And by categorizing it 32 00:01:11,370 --> 00:01:13,680 and identifying these different types of traffic, 33 00:01:13,680 --> 00:01:17,130 I can then prioritize that traffic and route it differently. 34 00:01:17,130 --> 00:01:19,560 So I might determine how much bandwidth is required 35 00:01:19,560 --> 00:01:21,240 for each of those types of traffic. 36 00:01:21,240 --> 00:01:23,940 And I can efficiently use my Wide Area Network links 37 00:01:23,940 --> 00:01:27,120 and all that bandwidth available for maximum utilization 38 00:01:27,120 --> 00:01:29,670 and save me bandwidth cost over time. 39 00:01:29,670 --> 00:01:31,560 This can help me identify the types of traffic 40 00:01:31,560 --> 00:01:33,390 that I should drop whenever there's going to be some kind 41 00:01:33,390 --> 00:01:35,970 of congestion, because if you look at the average load, 42 00:01:35,970 --> 00:01:38,490 there's always going to be some peaks and some valleys. 43 00:01:38,490 --> 00:01:40,470 And so we want to be able to figure that out, 44 00:01:40,470 --> 00:01:42,060 and we need to be able to categorize things 45 00:01:42,060 --> 00:01:44,250 to fit within our bandwidth limitations. 46 00:01:44,250 --> 00:01:47,880 So for example, if we have things like VoIP, or Voiceover IP 47 00:01:47,880 --> 00:01:50,460 or video service, they need to have a higher priority 48 00:01:50,460 --> 00:01:52,230 because if I'm talking to you on a phone, 49 00:01:52,230 --> 00:01:54,240 I don't want a high amount of latency. 50 00:01:54,240 --> 00:01:56,400 If I'm checking my bank balances, for instance, though, 51 00:01:56,400 --> 00:01:59,310 I can wait another half a second for the webpage to load. 52 00:01:59,310 --> 00:02:00,570 If I'm listening to you talk, 53 00:02:00,570 --> 00:02:03,210 that half a second delay starts sounding like an echo, 54 00:02:03,210 --> 00:02:05,190 and it gives me a horrible service level. 55 00:02:05,190 --> 00:02:06,900 So we want to be able to solve that. 56 00:02:06,900 --> 00:02:09,690 And to do that, we use Quality of Service. 57 00:02:09,690 --> 00:02:12,420 Now, there are different categories of Quality of Service. 58 00:02:12,420 --> 00:02:16,260 There are three big ones known as Delay, Jitter and Drops. 59 00:02:16,260 --> 00:02:17,700 When I talk about Delay, 60 00:02:17,700 --> 00:02:19,410 this happens when you look at the time 61 00:02:19,410 --> 00:02:22,590 that a packet travels from the source to the destination. 62 00:02:22,590 --> 00:02:24,360 This is measured in milliseconds, 63 00:02:24,360 --> 00:02:26,850 and it's not a big deal if you're dealing with data traffic, 64 00:02:26,850 --> 00:02:28,950 but if you're dealing with voice or video, 65 00:02:28,950 --> 00:02:30,960 Delay is an especially big thing, 66 00:02:30,960 --> 00:02:33,210 especially if you're doing things live, 67 00:02:33,210 --> 00:02:34,350 like talking on the phone 68 00:02:34,350 --> 00:02:37,080 or doing a livestream or something like that. 69 00:02:37,080 --> 00:02:40,050 Now, Jitter is an uneven arrival of packets, 70 00:02:40,050 --> 00:02:42,900 and this is especially bad in Voiceover IP traffic 71 00:02:42,900 --> 00:02:44,730 because you're using something like UDP. 72 00:02:44,730 --> 00:02:46,477 And so if I was saying something to you like, 73 00:02:46,477 --> 00:02:49,920 "My name is Jason," and you got, "Jason, my name is," 74 00:02:49,920 --> 00:02:51,630 it sounds kind of weird, right? 75 00:02:51,630 --> 00:02:53,580 Now, usually, it's not big chunks like that, 76 00:02:53,580 --> 00:02:55,920 but instead, it's little bits, and you'll hear these glick 77 00:02:55,920 --> 00:02:58,590 and glock sounds that kind of make it jumble up 78 00:02:58,590 --> 00:03:00,810 because of that Jitter, and this really sounds bad, 79 00:03:00,810 --> 00:03:04,230 and it's a bad user experience if you're using Voiceover IP. 80 00:03:04,230 --> 00:03:06,060 And so Jitter is a really bad thing 81 00:03:06,060 --> 00:03:08,040 when you're dealing with voice and video. 82 00:03:08,040 --> 00:03:10,710 Now, the third thing we have is what's known as a Drop. 83 00:03:10,710 --> 00:03:13,440 Drops are going to occur during network congestion. 84 00:03:13,440 --> 00:03:15,270 When the network becomes too congested, 85 00:03:15,270 --> 00:03:17,340 the router simply can't keep up with demand 86 00:03:17,340 --> 00:03:18,960 and the queue starts overflowing 87 00:03:18,960 --> 00:03:20,790 and it'll start dropping packets. 88 00:03:20,790 --> 00:03:22,710 This is the way it deals with packet loss, 89 00:03:22,710 --> 00:03:25,620 and if you're using TCP, it'll just send it again. 90 00:03:25,620 --> 00:03:29,070 But again, if I'm dealing with VoIP, VoIP is usually UDP. 91 00:03:29,070 --> 00:03:30,390 And so if we're talking and, all of a sudden, 92 00:03:30,390 --> 00:03:33,180 my voice cuts out like that, that would be bad too. 93 00:03:33,180 --> 00:03:36,240 That's why we don't want to have packet Drop on a VoIP call, 94 00:03:36,240 --> 00:03:38,490 and so we want to make sure that that doesn't happen. 95 00:03:38,490 --> 00:03:40,800 These network Drops are something that can be avoided 96 00:03:40,800 --> 00:03:43,560 by doing the proper Quality of Service as well. 97 00:03:43,560 --> 00:03:44,700 So when we deal with this, 98 00:03:44,700 --> 00:03:47,250 we have to think about effective bandwidth. 99 00:03:47,250 --> 00:03:48,720 What is our effective bandwidth? 100 00:03:48,720 --> 00:03:50,340 This is an important concept. 101 00:03:50,340 --> 00:03:52,440 So let's look at this client and this server. 102 00:03:52,440 --> 00:03:54,180 There's probably a lot more to this network 103 00:03:54,180 --> 00:03:55,470 than what I'm showing you here on the screen, 104 00:03:55,470 --> 00:03:58,170 but I simplified it down for this example. 105 00:03:58,170 --> 00:04:00,000 Here, you can see, I have my client on the left 106 00:04:00,000 --> 00:04:01,680 and he wants to talk to the server. 107 00:04:01,680 --> 00:04:03,000 So he goes up through the switch, 108 00:04:03,000 --> 00:04:05,910 which uses 100 megabit per second CAT-5 cable. 109 00:04:05,910 --> 00:04:09,030 Then he goes through a WAN link over a 256 kilobit 110 00:04:09,030 --> 00:04:12,330 per second connection because he is using an old DSL line. 111 00:04:12,330 --> 00:04:15,900 Then that connects from that ISP over a T-1 connection 112 00:04:15,900 --> 00:04:17,220 to another router. 113 00:04:17,220 --> 00:04:19,560 That router connects through an E-1 connection 114 00:04:19,560 --> 00:04:21,570 to another router, and from that router, 115 00:04:21,570 --> 00:04:24,513 it goes down a WAN link over a 512 kilobit per second 116 00:04:24,513 --> 00:04:27,150 connection, and then down to a switch 117 00:04:27,150 --> 00:04:29,910 with a gigabit connection down to the server. 118 00:04:29,910 --> 00:04:32,550 Now, what is my effective bandwidth? 119 00:04:32,550 --> 00:04:35,460 Well, it's 256 kilobits per second, 120 00:04:35,460 --> 00:04:37,860 because no matter how fast any of the other links are, 121 00:04:37,860 --> 00:04:40,560 whatever the lowest link is inside of this connection, 122 00:04:40,560 --> 00:04:42,690 that is going to be your effective bandwidth. 123 00:04:42,690 --> 00:04:44,640 So when we talk about Quality of Service categories 124 00:04:44,640 --> 00:04:46,380 in our next lesson, we're going to be talking 125 00:04:46,380 --> 00:04:48,240 about how we can alleviate this problem 126 00:04:48,240 --> 00:04:51,240 of this effective bandwidth and try to get more out of it 127 00:04:51,240 --> 00:04:52,530 because we need to be able to increase 128 00:04:52,530 --> 00:04:53,640 our available bandwidth. 129 00:04:53,640 --> 00:04:57,570 But in this example, we're limited to 256 kilobits, 130 00:04:57,570 --> 00:05:00,060 which is going to be really, really slow for us. 131 00:05:00,060 --> 00:05:02,010 Now, I like to think about effective bandwidth 132 00:05:02,010 --> 00:05:03,750 like water flowing through pipes. 133 00:05:03,750 --> 00:05:06,030 I can have big pipes and I can have little pipes, 134 00:05:06,030 --> 00:05:07,110 and if I have little pipes, 135 00:05:07,110 --> 00:05:09,210 I'm going to get less water per second through it 136 00:05:09,210 --> 00:05:10,920 than if I have a really big pipe. 137 00:05:10,920 --> 00:05:12,000 And so this is the idea. 138 00:05:12,000 --> 00:05:13,170 If you think about a big funnel, 139 00:05:13,170 --> 00:05:15,390 it can start to back up on us, right? 140 00:05:15,390 --> 00:05:16,980 That's the concept, and we have to figure out 141 00:05:16,980 --> 00:05:20,100 how we can fix that by using Quality of Service effectively, 142 00:05:20,100 --> 00:05:22,550 which we're going to discuss more in the next video.