1 00:00:00,600 --> 00:00:01,800 When we deal with the quality 2 00:00:01,800 --> 00:00:04,350 of service categorization, we first have to ask, 3 00:00:04,350 --> 00:00:06,990 what is the purpose of quality of service? 4 00:00:06,990 --> 00:00:08,580 Now, the purpose of quality of service 5 00:00:08,580 --> 00:00:10,800 is all about categorizing your traffic 6 00:00:10,800 --> 00:00:13,410 and putting it into buckets so we can apply a policy 7 00:00:13,410 --> 00:00:15,990 to certain buckets based on those traffic categories, 8 00:00:15,990 --> 00:00:19,020 and then we can prioritize them based on that. 9 00:00:19,020 --> 00:00:21,630 I like to tell stories and use analogies in my classes 10 00:00:21,630 --> 00:00:24,090 to help drive home points, and so since we're talking about 11 00:00:24,090 --> 00:00:25,710 quality of service and traffic, 12 00:00:25,710 --> 00:00:28,620 I think it's important to talk about real world traffic. 13 00:00:28,620 --> 00:00:31,020 Now, to alleviate this, they applied the idea 14 00:00:31,020 --> 00:00:33,720 of quality of service to their traffic system. 15 00:00:33,720 --> 00:00:36,030 They have three different categories of cars. 16 00:00:36,030 --> 00:00:39,030 They have the first car, which is general public, right? 17 00:00:39,030 --> 00:00:40,980 Anybody who gets in the road and starts driving, 18 00:00:40,980 --> 00:00:42,510 they are part of this group. 19 00:00:42,510 --> 00:00:43,590 Then there's another category 20 00:00:43,590 --> 00:00:45,603 called high-occupancy vehicles or HOV. 21 00:00:46,440 --> 00:00:47,550 And so if I'm driving my car 22 00:00:47,550 --> 00:00:49,650 and I have at least two other passengers with me, 23 00:00:49,650 --> 00:00:51,960 I can get into special HOV-only lanes, 24 00:00:51,960 --> 00:00:54,120 and I can go a little bit of faster. 25 00:00:54,120 --> 00:00:57,180 Now, the third bucket is toll roads or pay roads, 26 00:00:57,180 --> 00:00:58,650 and you have to pay to get on these roads. 27 00:00:58,650 --> 00:00:59,730 And based on the time of day 28 00:00:59,730 --> 00:01:01,050 and the amount of traffic there is, 29 00:01:01,050 --> 00:01:03,660 they actually increase or decrease the price. 30 00:01:03,660 --> 00:01:06,570 Now, if it's during rush hour, you might pay 5 or $10 31 00:01:06,570 --> 00:01:08,400 to get in one of those special toll lanes, 32 00:01:08,400 --> 00:01:10,860 but they're going to travel a whole lot faster 33 00:01:10,860 --> 00:01:14,400 than the regular general commuter lanes or those HOV lanes. 34 00:01:14,400 --> 00:01:16,950 Now, what does this mean in terms of quality of service? 35 00:01:16,950 --> 00:01:18,900 Well, it's really the same thing. 36 00:01:18,900 --> 00:01:20,550 We take our traffic and we go, 37 00:01:20,550 --> 00:01:23,340 okay, this is web traffic and this is email traffic 38 00:01:23,340 --> 00:01:25,200 and this is voice or video traffic. 39 00:01:25,200 --> 00:01:28,110 And based on those buckets, we assign a priority to them. 40 00:01:28,110 --> 00:01:29,880 And we let certain traffic go first, 41 00:01:29,880 --> 00:01:31,560 and we let it get there faster. 42 00:01:31,560 --> 00:01:33,150 Now, when we categorize this traffic, 43 00:01:33,150 --> 00:01:35,820 we start to determine our network performance based on it. 44 00:01:35,820 --> 00:01:37,200 We can start figuring out the requirements 45 00:01:37,200 --> 00:01:38,940 based on the different traffic types, 46 00:01:38,940 --> 00:01:41,100 and whether it's voice or video or data. 47 00:01:41,100 --> 00:01:42,810 If we're starting to deal with voice or video, 48 00:01:42,810 --> 00:01:44,490 because there are things like streaming media, 49 00:01:44,490 --> 00:01:46,500 especially in real time like a Skype call 50 00:01:46,500 --> 00:01:48,090 or voiceover IP service, 51 00:01:48,090 --> 00:01:49,710 I want to have a very low delay, 52 00:01:49,710 --> 00:01:51,690 and therefore, a higher priority. 53 00:01:51,690 --> 00:01:54,150 This way, I can do this stuff for streaming media 54 00:01:54,150 --> 00:01:56,820 and voice services and prevent those jitters and drops 55 00:01:56,820 --> 00:01:59,190 and things like that that we talked about before. 56 00:01:59,190 --> 00:02:00,930 Now, this is something that I want to make sure 57 00:02:00,930 --> 00:02:03,420 has a good high priority so I can get it through. 58 00:02:03,420 --> 00:02:05,610 Instead, if I have something with a low priority, 59 00:02:05,610 --> 00:02:07,560 that might be something like web browsing 60 00:02:07,560 --> 00:02:09,389 or non-mission critical data. 61 00:02:09,389 --> 00:02:11,910 For instance, if my employees are surfing on Facebook, 62 00:02:11,910 --> 00:02:13,800 that would be a very low priority, 63 00:02:13,800 --> 00:02:15,270 or if I deal with email. 64 00:02:15,270 --> 00:02:17,130 Email is generally a low priority 65 00:02:17,130 --> 00:02:18,960 when it comes to quality of service. 66 00:02:18,960 --> 00:02:19,860 Now, why is that? 67 00:02:19,860 --> 00:02:21,480 Isn't email important to you? 68 00:02:21,480 --> 00:02:24,060 Well, because most email is done as a store 69 00:02:24,060 --> 00:02:25,950 and forward communication map. 70 00:02:25,950 --> 00:02:27,570 This means when I send email, 71 00:02:27,570 --> 00:02:29,940 it can sit on my server for 5 or 10 minutes 72 00:02:29,940 --> 00:02:31,620 before it's actually sent out to the end user, 73 00:02:31,620 --> 00:02:33,270 and they'll never realize it. 74 00:02:33,270 --> 00:02:34,380 So that's okay. 75 00:02:34,380 --> 00:02:35,430 It can be a low priority. 76 00:02:35,430 --> 00:02:37,050 It'll still get there eventually. 77 00:02:37,050 --> 00:02:39,360 But if I did the same thing with VoIP traffic, 78 00:02:39,360 --> 00:02:41,790 even delaying it by half a second or a second, 79 00:02:41,790 --> 00:02:44,070 you're going to hear jitters and bumps and echoes, 80 00:02:44,070 --> 00:02:45,930 and that would be a horrible service. 81 00:02:45,930 --> 00:02:48,600 So we want to make sure you get high quality of service 82 00:02:48,600 --> 00:02:51,540 for VoIP and lower priority for email. 83 00:02:51,540 --> 00:02:53,100 Now, that's just the way we have it set up. 84 00:02:53,100 --> 00:02:54,810 You can have it set up however you want. 85 00:02:54,810 --> 00:02:55,650 As long as you understand 86 00:02:55,650 --> 00:02:57,480 what your quality of service policy is 87 00:02:57,480 --> 00:03:00,450 and you understand it and your users understand it, 88 00:03:00,450 --> 00:03:01,950 this is going to be okay. 89 00:03:01,950 --> 00:03:03,810 The best way to do that is to document it 90 00:03:03,810 --> 00:03:05,460 and share that with your users. 91 00:03:05,460 --> 00:03:08,010 You want to make sure your users understand your policy 92 00:03:08,010 --> 00:03:09,660 because this will help make sure 93 00:03:09,660 --> 00:03:11,070 that they don't have problems 94 00:03:11,070 --> 00:03:13,410 and start reporting that back to your service desk. 95 00:03:13,410 --> 00:03:15,870 You can do this by posting it to your internal website. 96 00:03:15,870 --> 00:03:18,480 You might post it as part of your indoctrination paperwork 97 00:03:18,480 --> 00:03:20,040 or whatever method you want. 98 00:03:20,040 --> 00:03:22,260 You want to make sure those users understand it 99 00:03:22,260 --> 00:03:23,760 because they're the ones who are going to be there 100 00:03:23,760 --> 00:03:25,890 surfing Facebook or watching YouTube. 101 00:03:25,890 --> 00:03:28,080 If you've categorized it as a low priority, 102 00:03:28,080 --> 00:03:29,640 they're going to think something's broken. 103 00:03:29,640 --> 00:03:30,870 Or if they know it's a low priority, 104 00:03:30,870 --> 00:03:32,100 they understand it's not broken, 105 00:03:32,100 --> 00:03:34,050 it's just your corporate policy. 106 00:03:34,050 --> 00:03:35,850 Now, if they're going to be surfing something on the web 107 00:03:35,850 --> 00:03:38,160 that's mission critical, that's a higher priority, 108 00:03:38,160 --> 00:03:39,600 and it's going to get preferential treatment 109 00:03:39,600 --> 00:03:40,890 with your quality of service, 110 00:03:40,890 --> 00:03:42,300 they should know that too. 111 00:03:42,300 --> 00:03:43,680 This is the idea here. 112 00:03:43,680 --> 00:03:44,970 We have to make sure that they understand 113 00:03:44,970 --> 00:03:46,470 how we categorize our traffic 114 00:03:46,470 --> 00:03:48,660 and what categories those get put into. 115 00:03:48,660 --> 00:03:51,480 Now, what are some ways that we can categorize our traffic? 116 00:03:51,480 --> 00:03:54,450 Well, there's really three different mechanisms you can use. 117 00:03:54,450 --> 00:03:57,000 We have best effort, integrated services, 118 00:03:57,000 --> 00:03:59,430 and differentiated services. 119 00:03:59,430 --> 00:04:00,870 Now, when we deal with best effort, 120 00:04:00,870 --> 00:04:03,270 this is when we don't have any quality of service at all. 121 00:04:03,270 --> 00:04:06,030 And so traffic is just first in, first out, 122 00:04:06,030 --> 00:04:07,590 every man for himself. 123 00:04:07,590 --> 00:04:10,560 We're going to do our best and just try to get it there. 124 00:04:10,560 --> 00:04:13,560 There's really no reordering of packets, there's no shaping. 125 00:04:13,560 --> 00:04:15,900 It's just pretty much no quality of service. 126 00:04:15,900 --> 00:04:18,570 First in, first out, best effort. 127 00:04:18,570 --> 00:04:21,870 The second type is known as Integrated Services or IntServ. 128 00:04:21,870 --> 00:04:24,270 This is also known as Hard QOS. 129 00:04:24,270 --> 00:04:25,230 There are different names for it 130 00:04:25,230 --> 00:04:26,850 depending on what company you're using 131 00:04:26,850 --> 00:04:28,920 and what routers and switches you're using. 132 00:04:28,920 --> 00:04:30,780 But the idea here is we're going to make strict 133 00:04:30,780 --> 00:04:32,970 bandwidth reservations. 134 00:04:32,970 --> 00:04:34,710 We might say that all web traffic 135 00:04:34,710 --> 00:04:36,870 is going to get 50% of our bandwidth, 136 00:04:36,870 --> 00:04:39,120 VoIP service is going to get 25%, 137 00:04:39,120 --> 00:04:41,910 and video service is going to get the remaining 25%. 138 00:04:41,910 --> 00:04:43,170 Now, by reserving bandwidth 139 00:04:43,170 --> 00:04:44,940 for each of these signaling devices, 140 00:04:44,940 --> 00:04:46,980 we now decide how much is going to be there 141 00:04:46,980 --> 00:04:49,050 for each of those three categories. 142 00:04:49,050 --> 00:04:50,670 Now, when we deal with DiffServ 143 00:04:50,670 --> 00:04:54,210 or differentiated services, also known as Soft QoS, 144 00:04:54,210 --> 00:04:56,880 those percentages become more of a suggestion. 145 00:04:56,880 --> 00:04:58,380 There's going to be this differentiation 146 00:04:58,380 --> 00:04:59,910 between different data types, 147 00:04:59,910 --> 00:05:01,350 but for each of these packets, 148 00:05:01,350 --> 00:05:03,150 it's going to be marked its own way. 149 00:05:03,150 --> 00:05:05,010 The routers and switches can then make decisions 150 00:05:05,010 --> 00:05:07,620 based on those markings, and they can fluctuate traffic 151 00:05:07,620 --> 00:05:09,570 a little bit as they need to. 152 00:05:09,570 --> 00:05:11,730 Now, this is referred to as Soft QoS 153 00:05:11,730 --> 00:05:14,580 because even though we set web up as maybe 50%, 154 00:05:14,580 --> 00:05:16,800 it's not as much web browsing going on right now, 155 00:05:16,800 --> 00:05:19,140 we can actually take away some of that 50% 156 00:05:19,140 --> 00:05:23,280 and give it over to VoIP and increase that from 25 to 35%. 157 00:05:23,280 --> 00:05:25,320 This way, when somebody wants to browse the web, 158 00:05:25,320 --> 00:05:27,720 we can then take back that extra from VoIP 159 00:05:27,720 --> 00:05:29,220 and give it back to web, 160 00:05:29,220 --> 00:05:31,260 back to that 50% it has originally had 161 00:05:31,260 --> 00:05:33,990 based on those markings and based on those categories. 162 00:05:33,990 --> 00:05:37,530 Now, if we're using hard QoS or that integrated services, 163 00:05:37,530 --> 00:05:39,900 even if we allocated 50% for web browsing 164 00:05:39,900 --> 00:05:41,760 and nobody's using web browsing, 165 00:05:41,760 --> 00:05:44,100 we're still going to have 50% sitting there, 166 00:05:44,100 --> 00:05:46,170 waiting to serve people for web browsing. 167 00:05:46,170 --> 00:05:47,400 And that's why a lot of companies 168 00:05:47,400 --> 00:05:49,890 prefer to use soft QoS instead. 169 00:05:49,890 --> 00:05:51,570 Now, let's take a look at it like this, 170 00:05:51,570 --> 00:05:53,070 because I like to use simple charts 171 00:05:53,070 --> 00:05:55,680 and graphs to try to make it easy to understand. 172 00:05:55,680 --> 00:05:57,090 With best effort at the top, 173 00:05:57,090 --> 00:05:59,010 you have no strict policies at all. 174 00:05:59,010 --> 00:06:00,990 And basically, you just make your best effort 175 00:06:00,990 --> 00:06:03,660 at providing everyone a good quality of service. 176 00:06:03,660 --> 00:06:06,150 Now, with DiffServ, you have less strict policies, 177 00:06:06,150 --> 00:06:08,280 also known as soft QoS. 178 00:06:08,280 --> 00:06:10,590 Now, it's better than the best effort approach, 179 00:06:10,590 --> 00:06:12,060 but it's still not the most efficient 180 00:06:12,060 --> 00:06:14,640 or effective method of providing a good quality of service 181 00:06:14,640 --> 00:06:16,290 to those who really need it. 182 00:06:16,290 --> 00:06:17,880 Now, with IntServ approaches, 183 00:06:17,880 --> 00:06:20,160 you're going to have more of a hard QoS limit. 184 00:06:20,160 --> 00:06:21,720 This is what we've talked about before. 185 00:06:21,720 --> 00:06:23,670 Now, this is going to give you the highest level of service 186 00:06:23,670 --> 00:06:25,620 to those within strict policies, 187 00:06:25,620 --> 00:06:28,260 and if you need a really strong quality of service level, 188 00:06:28,260 --> 00:06:31,320 then IntServ or hard QoS with its strict policies 189 00:06:31,320 --> 00:06:33,180 can really ensure that you get it. 190 00:06:33,180 --> 00:06:34,680 Now, the way I like to look at this 191 00:06:34,680 --> 00:06:38,040 is as bundles of QoS options that we can choose from. 192 00:06:38,040 --> 00:06:40,800 So which of these bundles is really the best? 193 00:06:40,800 --> 00:06:42,000 Well, it depends. 194 00:06:42,000 --> 00:06:44,490 It depends on your network and it depends on your needs, 195 00:06:44,490 --> 00:06:47,250 but most of the time, it's not going to be a best effort, 196 00:06:47,250 --> 00:06:48,570 because that's usually going to give you 197 00:06:48,570 --> 00:06:51,240 not as much quality as you're really going to want here. 198 00:06:51,240 --> 00:06:53,940 Now, when we start categorizing our traffic out there, 199 00:06:53,940 --> 00:06:55,980 we're going to start using these different mechanisms, 200 00:06:55,980 --> 00:06:58,107 either soft or hard QoS for doing that. 201 00:06:58,107 --> 00:07:00,780 And we can do that using classification and marketing. 202 00:07:00,780 --> 00:07:02,400 We can do it through congestion management 203 00:07:02,400 --> 00:07:03,660 and congestion avoidance. 204 00:07:03,660 --> 00:07:05,220 We can use policing and shaping, 205 00:07:05,220 --> 00:07:07,230 and we can also use link efficiency. 206 00:07:07,230 --> 00:07:10,710 All of these choices fall under a soft QoS or hard QoS, 207 00:07:10,710 --> 00:07:12,750 depending on your configuration that you've set up 208 00:07:12,750 --> 00:07:15,573 within your network appliances, firewalls, or routers.