1 1 00:00:00,590 --> 00:00:03,170 When we deal with the quality of service categorization, 2 2 00:00:03,170 --> 00:00:04,350 we first have to ask, 3 3 00:00:04,350 --> 00:00:07,000 what is the purpose of quality of service? 4 4 00:00:07,000 --> 00:00:09,250 Now, the purpose of quality of service is all about 5 5 00:00:09,250 --> 00:00:12,230 categorizing your traffic and putting it into buckets 6 6 00:00:12,230 --> 00:00:14,330 so we can apply a policy to certain buckets 7 7 00:00:14,330 --> 00:00:15,970 based on those traffic categories 8 8 00:00:15,970 --> 00:00:19,030 and then we can prioritize them based on that. 9 9 00:00:19,030 --> 00:00:21,640 I like to tell stories and use analogies in my classes 10 10 00:00:21,640 --> 00:00:23,400 to help drive home points. 11 11 00:00:23,400 --> 00:00:24,340 And so, since we're talking about 12 12 00:00:24,340 --> 00:00:25,960 quality of service and traffic, 13 13 00:00:25,960 --> 00:00:28,670 I think it's important to talk about real-world traffic. 14 14 00:00:28,670 --> 00:00:31,440 I live in the Baltimore, Washington D.C area. 15 15 00:00:31,440 --> 00:00:32,510 This area is known for having 16 16 00:00:32,510 --> 00:00:34,460 some really really bad traffic. 17 17 00:00:34,460 --> 00:00:36,870 Now, to alleviate this they applied the idea 18 18 00:00:36,870 --> 00:00:39,560 of quality of service to their traffic system. 19 19 00:00:39,560 --> 00:00:41,520 They have three different categories of cars. 20 20 00:00:41,520 --> 00:00:44,870 They have the first car, which is general public. 21 21 00:00:44,870 --> 00:00:46,810 Anybody who gets in the road and starts driving, 22 22 00:00:46,810 --> 00:00:48,340 they are part of this group. 23 23 00:00:48,340 --> 00:00:49,440 Then there's another category 24 24 00:00:49,440 --> 00:00:52,260 called high occupancy vehicles or HOV. 25 25 00:00:52,260 --> 00:00:53,410 And so, if I'm driving my car 26 26 00:00:53,410 --> 00:00:55,490 and I have at least two other passengers with me, 27 27 00:00:55,490 --> 00:00:57,760 I can get into special HOV only lanes 28 28 00:00:57,760 --> 00:00:59,600 and I can go a little bit faster. 29 29 00:00:59,600 --> 00:01:02,630 Now the third bucket is toll roads or pay roads. 30 30 00:01:02,630 --> 00:01:04,160 And you have to pay to get on these roads. 31 31 00:01:04,160 --> 00:01:05,240 And based on the time of day 32 32 00:01:05,240 --> 00:01:06,530 and the amount of traffic there is, 33 33 00:01:06,530 --> 00:01:09,150 they actually increase or decrease the price. 34 34 00:01:09,150 --> 00:01:12,040 Now, if it's during rush hour, you might pay 5 or $10 35 35 00:01:12,040 --> 00:01:13,890 to get in one of those special toll lanes. 36 36 00:01:13,890 --> 00:01:16,340 But, they're going to travel a whole lot faster 37 37 00:01:16,340 --> 00:01:19,890 than the regular general commuter lanes or those HOV lanes. 38 38 00:01:19,890 --> 00:01:22,440 Now, what does this mean in terms of quality of service? 39 39 00:01:22,440 --> 00:01:24,380 Well, it's really the same thing. 40 40 00:01:24,380 --> 00:01:27,500 We take our traffic and we go, okay, this is web traffic, 41 41 00:01:27,500 --> 00:01:29,080 and this is email traffic, 42 42 00:01:29,080 --> 00:01:30,930 and this is voice or video traffic. 43 43 00:01:30,930 --> 00:01:33,850 And based on those buckets we assign a priority to them. 44 44 00:01:33,850 --> 00:01:35,540 And we let certain traffic go first 45 45 00:01:35,540 --> 00:01:37,290 and we let it get there faster. 46 46 00:01:37,290 --> 00:01:38,870 Now, when we categorize this traffic 47 47 00:01:38,870 --> 00:01:41,540 we start to determine our network performance based on it. 48 48 00:01:41,540 --> 00:01:42,960 We can start figuring out the requirements 49 49 00:01:42,960 --> 00:01:44,620 based on the different traffic types 50 50 00:01:44,620 --> 00:01:46,890 and whether it's voice or video or data. 51 51 00:01:46,890 --> 00:01:48,630 If we're starting to deal with voice or video 52 52 00:01:48,630 --> 00:01:50,290 because there are things like streaming media 53 53 00:01:50,290 --> 00:01:52,310 especially in real-time like a Skype call 54 54 00:01:52,310 --> 00:01:53,900 or a Voice over IP service, 55 55 00:01:53,900 --> 00:01:55,520 I want to have a very low delay 56 56 00:01:55,520 --> 00:01:57,510 and therefore a higher priority. 57 57 00:01:57,510 --> 00:01:59,160 This way I can do this stuff 58 58 00:01:59,160 --> 00:02:00,860 for streaming media and voice services 59 59 00:02:00,860 --> 00:02:03,340 and prevent those jitters and drops and things like that 60 60 00:02:03,340 --> 00:02:04,980 that we talked about before. 61 61 00:02:04,980 --> 00:02:06,740 Now, this is something that I want to make sure 62 62 00:02:06,740 --> 00:02:09,220 has a good high priority so I can get it through. 63 63 00:02:09,220 --> 00:02:11,420 Instead if I have something with a low priority 64 64 00:02:11,420 --> 00:02:13,360 that might be something like web browsing 65 65 00:02:13,360 --> 00:02:15,160 or non-mission critical data. 66 66 00:02:15,160 --> 00:02:17,710 For instance, if my employees are surfing on Facebook, 67 67 00:02:17,710 --> 00:02:19,610 that would be a very low priority. 68 68 00:02:19,610 --> 00:02:21,060 Or if I deal with email, 69 69 00:02:21,060 --> 00:02:22,910 email is generally a low priority 70 70 00:02:22,910 --> 00:02:24,770 when it comes to quality of service. 71 71 00:02:24,770 --> 00:02:27,290 Now why is that, isn't email important to you? 72 72 00:02:27,290 --> 00:02:29,270 Well, because most email is done 73 73 00:02:29,270 --> 00:02:31,760 as a store and forward communication method. 74 74 00:02:31,760 --> 00:02:33,370 This means when I send email, 75 75 00:02:33,370 --> 00:02:35,740 it can sit on my server for 5 or 10 minutes 76 76 00:02:35,740 --> 00:02:37,430 before it's actually sent out to the end-user 77 77 00:02:37,430 --> 00:02:39,070 and they'll never realize it. 78 78 00:02:39,070 --> 00:02:40,170 So that's okay. 79 79 00:02:40,170 --> 00:02:42,860 It can be a low priority, it'll still get there eventually. 80 80 00:02:42,860 --> 00:02:45,180 But if I did the same thing with VoIP traffic, 81 81 00:02:45,180 --> 00:02:47,590 even delaying it by half a second or a second, 82 82 00:02:47,590 --> 00:02:49,810 you're going to hear jitters and bumps and echoes 83 83 00:02:49,810 --> 00:02:51,720 and that would be a horrible service. 84 84 00:02:51,720 --> 00:02:54,380 So, we want to make sure you get high quality of service 85 85 00:02:54,380 --> 00:02:57,340 for VoIP and lower priority for email. 86 86 00:02:57,340 --> 00:02:58,860 Now that's just the way we have it set up. 87 87 00:02:58,860 --> 00:03:00,610 You can have it set up however you want 88 88 00:03:00,610 --> 00:03:01,443 as long as you understand 89 89 00:03:01,443 --> 00:03:03,300 what your quality of service policy is, 90 90 00:03:03,300 --> 00:03:05,873 and you understand it, and your users understand it, 91 91 00:03:05,873 --> 00:03:07,760 this is going to be okay. 92 92 00:03:07,760 --> 00:03:09,620 The best way to do that is to document it 93 93 00:03:09,620 --> 00:03:11,270 and share that with your users. 94 94 00:03:11,270 --> 00:03:13,760 You want to make sure your users understand your policy 95 95 00:03:13,760 --> 00:03:15,460 because this will help make sure 96 96 00:03:15,460 --> 00:03:16,810 that they don't have problems 97 97 00:03:16,810 --> 00:03:19,120 and start reporting that back to your service desk. 98 98 00:03:19,120 --> 00:03:21,590 You can do this by posting it to your internal website. 99 99 00:03:21,590 --> 00:03:24,200 You might post as part of your indoctrination paperwork 100 100 00:03:24,200 --> 00:03:25,800 or whatever method you want. 101 101 00:03:25,800 --> 00:03:27,850 You want to make sure those users understand it 102 102 00:03:27,850 --> 00:03:29,360 because they're the ones who are going to be there 103 103 00:03:29,360 --> 00:03:31,480 surfing Facebook or watching YouTube. 104 104 00:03:31,480 --> 00:03:33,660 If you've categorized as a low priority, 105 105 00:03:33,660 --> 00:03:35,200 they're going to think something's broken. 106 106 00:03:35,200 --> 00:03:36,470 But if they know it's a low priority, 107 107 00:03:36,470 --> 00:03:37,690 they understand it's not broken 108 108 00:03:37,690 --> 00:03:39,630 it's just your corporate policy. 109 109 00:03:39,630 --> 00:03:40,650 Now, if they're going to be surfing 110 110 00:03:40,650 --> 00:03:42,660 something on the web that's mission critical, 111 111 00:03:42,660 --> 00:03:44,240 that's a higher priority and it's going to get 112 112 00:03:44,240 --> 00:03:46,460 preferential treatment with your quality of service, 113 113 00:03:46,460 --> 00:03:47,870 they should know that too. 114 114 00:03:47,870 --> 00:03:49,250 This is the idea here. 115 115 00:03:49,250 --> 00:03:50,570 We have to make sure that they understand 116 116 00:03:50,570 --> 00:03:51,990 how we categorize our traffic 117 117 00:03:51,990 --> 00:03:54,260 and what categories those get put into. 118 118 00:03:54,260 --> 00:03:57,050 Now, what are some ways that we can categorize our traffic? 119 119 00:03:57,050 --> 00:04:00,010 Well, there's really three different mechanisms you can use. 120 120 00:04:00,010 --> 00:04:02,600 We have best effort, integrated services, 121 121 00:04:02,600 --> 00:04:04,570 and differentiated services. 122 122 00:04:04,570 --> 00:04:06,110 Now, when we use best effort 123 123 00:04:06,110 --> 00:04:08,480 this is when we don't have any quality of service at all 124 124 00:04:08,480 --> 00:04:11,240 and so traffic is just first in, first out, 125 125 00:04:11,240 --> 00:04:12,820 every man for himself. 126 126 00:04:12,820 --> 00:04:15,180 We're going to do our best and just try to get it there. 127 127 00:04:15,180 --> 00:04:16,880 There's really no reordering of packets. 128 128 00:04:16,880 --> 00:04:18,080 There's no shaping. 129 129 00:04:18,080 --> 00:04:20,390 It's just pretty much new quality of service. 130 130 00:04:20,390 --> 00:04:23,120 First in, first out, best effort. 131 131 00:04:23,120 --> 00:04:26,440 The second type is known as integrated services or IntServ. 132 132 00:04:26,440 --> 00:04:28,820 This is also known as hard QoS. 133 133 00:04:28,820 --> 00:04:29,780 There are different names for it 134 134 00:04:29,780 --> 00:04:31,350 depending on what company you're using 135 135 00:04:31,350 --> 00:04:33,450 and what routers and switches you're using. 136 136 00:04:33,450 --> 00:04:34,430 But the idea here is, 137 137 00:04:34,430 --> 00:04:36,810 we're going to make strict bandwidth reservations. 138 138 00:04:36,810 --> 00:04:38,600 We might say that all web traffic 139 139 00:04:38,600 --> 00:04:40,190 is going to get 50% of our bandwidth, 140 140 00:04:40,190 --> 00:04:42,880 VoIP service is going to get 25%, 141 141 00:04:42,880 --> 00:04:45,810 and video service is going to get the remaining 25%. 142 142 00:04:45,810 --> 00:04:47,060 Now, by reserving bandwidth 143 143 00:04:47,060 --> 00:04:48,640 for each of these signaling devices, 144 144 00:04:48,640 --> 00:04:50,860 we now decide how much is going to be there 145 145 00:04:50,860 --> 00:04:52,920 for each of those three categories. 146 146 00:04:52,920 --> 00:04:56,220 Now, when we do a DiffServ or differentiated services, 147 147 00:04:56,220 --> 00:04:57,767 also known as soft QoS, 148 148 00:04:57,767 --> 00:05:00,770 those percentages become more of a suggestion. 149 149 00:05:00,770 --> 00:05:02,270 There's going to be this differentiation 150 150 00:05:02,270 --> 00:05:03,790 between different data types 151 151 00:05:03,790 --> 00:05:05,260 but for each of these packets, 152 152 00:05:05,260 --> 00:05:07,030 it's going to be marked its own way. 153 153 00:05:07,030 --> 00:05:08,890 The routers and switches can then make decisions 154 154 00:05:08,890 --> 00:05:10,100 based on those markings 155 155 00:05:10,100 --> 00:05:13,480 and they can fluctuate traffic a little bit as they need to. 156 156 00:05:13,480 --> 00:05:15,600 Now, this is referred to as soft QoS 157 157 00:05:15,600 --> 00:05:18,460 because even though we set web up as maybe 50%, 158 158 00:05:18,460 --> 00:05:20,700 it's not as much web browsing going on right now 159 159 00:05:20,700 --> 00:05:22,940 we can actually take away some of that 50% 160 160 00:05:22,940 --> 00:05:27,150 and give it over to VoIP and increase that from 25 to 35%. 161 161 00:05:27,150 --> 00:05:29,210 This way, when somebody wants to browse the web, 162 162 00:05:29,210 --> 00:05:31,550 we can then take back that extra from VoIP 163 163 00:05:31,550 --> 00:05:35,130 and give it back to web back to that 50% was originally had 164 164 00:05:35,130 --> 00:05:37,880 based on those markings and based on those categories. 165 165 00:05:37,880 --> 00:05:41,410 Now, if we were using hard QoS or that integrated services, 166 166 00:05:41,410 --> 00:05:43,760 even if we allocate 50% for web browsing 167 167 00:05:43,760 --> 00:05:45,660 and nobody's using web browsing, 168 168 00:05:45,660 --> 00:05:47,970 we're still going to have 50% sitting there 169 169 00:05:47,970 --> 00:05:49,970 waiting to serve people for web browsing. 170 170 00:05:49,970 --> 00:05:53,770 And that's why a lot of companies prefer to use soft QS. 171 171 00:05:53,770 --> 00:05:55,480 Now, let's take a look at it like this 172 172 00:05:55,480 --> 00:05:57,620 because I like to use simple charts and graphs 173 173 00:05:57,620 --> 00:05:59,570 to try to make it easy to understand. 174 174 00:05:59,570 --> 00:06:00,990 With best effort at the top, 175 175 00:06:00,990 --> 00:06:02,800 you have no strict policies at all. 176 176 00:06:02,800 --> 00:06:04,900 And basically, you just make your best effort 177 177 00:06:04,900 --> 00:06:07,540 at providing everyone a good quality of service. 178 178 00:06:07,540 --> 00:06:10,040 Now with DiffServ you have less strict policies, 179 179 00:06:10,040 --> 00:06:12,160 also known as soft QS. 180 180 00:06:12,160 --> 00:06:14,480 Now it's better than the best effort approach 181 181 00:06:14,480 --> 00:06:15,940 but it's still not the most efficient 182 182 00:06:15,940 --> 00:06:18,530 or effective method of providing a good quality of service 183 183 00:06:18,530 --> 00:06:20,170 to those who really need it. 184 184 00:06:20,170 --> 00:06:21,770 Now with IntServ approaches 185 185 00:06:21,770 --> 00:06:24,030 you're going to have more of a hard QoS limit. 186 186 00:06:24,030 --> 00:06:25,600 This is what we've talked about before. 187 187 00:06:25,600 --> 00:06:27,560 Now, this is going to give you the highest level of service 188 188 00:06:27,560 --> 00:06:29,480 to those within strict policies. 189 189 00:06:29,480 --> 00:06:32,160 And if you need a really strong quality of service level 190 190 00:06:32,160 --> 00:06:35,190 then IntServ or hard QoS with a strict policies 191 191 00:06:35,190 --> 00:06:37,070 can really ensure that you get it. 192 192 00:06:37,070 --> 00:06:38,570 Now, the way I like to look at this 193 193 00:06:38,570 --> 00:06:41,940 is as bundles of QoS options that we can choose from. 194 194 00:06:41,940 --> 00:06:44,700 So which of these bundles is really the best? 195 195 00:06:44,700 --> 00:06:45,890 Well, it depends. 196 196 00:06:45,890 --> 00:06:48,370 It depends on your network and it depends on your needs. 197 197 00:06:48,370 --> 00:06:51,130 But most of the time, it's not going to be a best effort 198 198 00:06:51,130 --> 00:06:52,450 because that's usually going to give you 199 199 00:06:52,450 --> 00:06:55,130 not as much quality as you're really going to want here. 200 200 00:06:55,130 --> 00:06:57,810 Now, when we start categorizing our traffic out there 201 201 00:06:57,810 --> 00:06:59,840 we're going to start using these different mechanisms, 202 202 00:06:59,840 --> 00:07:02,210 either soft or hard QS, for doing that. 203 203 00:07:02,210 --> 00:07:04,670 And we can do that using classification and marking. 204 204 00:07:04,670 --> 00:07:06,280 We can do it through congestion management 205 205 00:07:06,280 --> 00:07:07,560 and congestion avoidance. 206 206 00:07:07,560 --> 00:07:09,110 We can use policing and shaping. 207 207 00:07:09,110 --> 00:07:11,110 And we can also use link efficiency. 208 208 00:07:11,110 --> 00:07:14,610 All of these choices fall under a soft QoS or hard QoS 209 209 00:07:14,610 --> 00:07:16,630 depending on your configuration that you've set up 210 210 00:07:16,630 --> 00:07:19,503 within your network appliances, firewalls, or routers.