WEBVTT 1 00:00.000 --> 00:02.520 Alright, let's jump into this challenge. 2 00:02.520 --> 00:06.700 Once again, we are going to be faced with converting between per-hot behaviors 3 00:06.700 --> 00:07.520 and decimal and 4 00:07.520 --> 00:09.760 maybe the other way around. 5 00:09.760 --> 00:12.560 And we're actually given a kind of interesting challenge question in this. 6 00:12.560 --> 00:16.500 So as the question above says, we're going to start by converting some of our 7 00:16.500 --> 00:17.040 per-hot 8 00:17.040 --> 00:19.040 behaviors into decimal. 9 00:19.040 --> 00:22.560 So this is similar to what we did earlier. 10 00:22.560 --> 00:25.560 Not only earlier in this skill, but earlier in the course. 11 00:25.560 --> 00:27.560 And so we've got AF11. 12 00:27.560 --> 00:29.640 So let's remember our equation. 13 00:29.640 --> 00:32.640 We have 8x plus 2y. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 13 00:29.640 --> 00:32.640 We have 8x plus 2y. 14 00:32.640 --> 00:36.790 And so I'm going to multiply the first by 8, multiply the second by 2, add them 15 00:36.790 --> 00:37.560 together. 16 00:37.560 --> 00:41.040 8 times 1 plus 2 times 1, that's just 8 plus 2. 17 00:41.040 --> 00:44.600 And so AF11 has a decimal value of 10. 18 00:44.600 --> 00:48.560 Meanwhile AF33, same equation here. 19 00:48.560 --> 00:52.600 We're going to say it's 8 times 3 plus 2 times 3. 20 00:52.600 --> 00:56.560 That would be the first 3 here, second 3 here. 21 00:56.560 --> 01:01.160 And so that's 24 plus 6, and the answer there would be 30. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 21 00:56.560 --> 01:01.160 And so that's 24 plus 6, and the answer there would be 30. 22 01:01.160 --> 01:05.160 So that's the first set of equations. 23 01:05.160 --> 01:07.360 Let's also not forget how we do a CS. 24 01:07.360 --> 01:11.160 For example, if we have a CS2, we simply multiply this number by 8. 25 01:11.160 --> 01:12.920 So that would be 16. 26 01:12.920 --> 01:16.740 And of course, expedited forwarding, there's no equation for it because there's 27 01:16.740 --> 01:17.320 no numbers 28 01:17.320 --> 01:20.000 in this per-hot behavior name. 29 01:20.000 --> 01:23.360 And so we just have to remember that it's 46. 30 01:23.360 --> 01:24.400 There we go. 31 01:24.400 --> 01:25.960 So that's the first question. 32 01:25.960 --> 01:31.160 Which assured forwarding per-hot behavior represents a decimal value of 36? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 32 01:25.960 --> 01:31.160 Which assured forwarding per-hot behavior represents a decimal value of 36? 33 01:31.160 --> 01:36.360 So now we're starting sort of here, and we're trying to get back to an assured 34 01:36.360 --> 01:37.440 forwarding 35 01:37.440 --> 01:40.160 name, a per-hot behavior at the end. 36 01:40.160 --> 01:42.160 And so how do we go about doing that? 37 01:42.160 --> 01:43.760 We're going to do the same thing here. 38 01:43.760 --> 01:48.160 We're just going to use division and try to get back to this concept of having 39 01:48.160 --> 01:48.720 so many 40 01:48.720 --> 01:50.360 eights and so many twos. 41 01:50.360 --> 01:55.680 The good news is, as long as this is a valid assured forwarding number, we'll 42 01:55.680 --> 01:55.880 all 43 01:55.880 --> 02:01.200 always be able to have a sum number of eights and some number of twos, and the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 43 01:55.880 --> 02:01.200 always be able to have a sum number of eights and some number of twos, and the 44 02:01.200 --> 02:02.000 math will 45 02:02.000 --> 02:03.400 work out. 46 02:03.400 --> 02:06.480 So what we do to start with is we want to find the eights. 47 02:06.480 --> 02:10.400 And the way we do that is we simply divide by 8. 48 02:10.400 --> 02:16.580 And so 36 divided by 8, we could say is 4 and a half, but ultimately it's 4 as 49 02:16.580 --> 02:17.120 our whole 50 02:17.120 --> 02:21.280 number, and it has a remainder of also 4. 51 02:21.280 --> 02:24.640 Because 36 divided, well, let's do it the other way. 52 02:24.640 --> 02:30.040 8 times 4 would be 32, and 32 is still 4 off from 36. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 52 02:24.640 --> 02:30.040 8 times 4 would be 32, and 32 is still 4 off from 36. 53 02:30.040 --> 02:31.520 So that would be our answer. 54 02:31.520 --> 02:34.320 So this is the number of eights. 55 02:34.320 --> 02:36.960 Next, we need to find the number of twos. 56 02:36.960 --> 02:42.520 And we're going to look at that by taking our remainder. 57 02:42.520 --> 02:46.800 And so now we have a 4, and we need to know how many twos are in the 4. 58 02:46.800 --> 02:52.680 Well, at that point we just divide it by 2, and so 4 divided by 2 is 2. 59 02:52.680 --> 02:56.320 So we have our first number, 4, we have our second number, 2. 60 02:56.320 --> 02:59.040 This is AF42. 61 02:59.040 --> 03:02.000 Now how confident am I? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 61 02:59.040 --> 03:02.000 Now how confident am I? 62 03:02.000 --> 03:04.480 Well, I just need to run this in reverse. 63 03:04.480 --> 03:06.040 I've got my equation up here. 64 03:06.040 --> 03:07.680 I can double check this. 65 03:07.680 --> 03:13.160 So it would be 8x plus 2y, 8 times 4, plus 2 times 2. 66 03:13.160 --> 03:18.760 So this is 32, this is 4, 32 plus 4, does indeed equal 36. 67 03:18.760 --> 03:24.320 So decimal value of 36 converts to AF42, and the way I do that is again, divide 68 03:24.320 --> 03:24.680 by 8 to 69 03:24.680 --> 03:28.440 get my whole number, divide the remainder by 2 to get the rest. 70 03:28.440 --> 03:30.720 So we do have a process in place for that. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 70 03:28.440 --> 03:30.720 So we do have a process in place for that. 71 03:30.720 --> 03:32.240 Lastly, this is the interesting one. 72 03:32.240 --> 03:38.960 A packet has a DSCP tag of decimal 22. 73 03:38.960 --> 03:43.770 What decimal tag would keep the packet in the same queue while giving it the 74 03:43.770 --> 03:44.640 lowest drop 75 03:44.640 --> 03:45.640 probability? 76 03:45.640 --> 03:49.560 Now we do have to make an assumption here, and that is that in order to stay in 77 03:49.560 --> 03:50.120 the same 78 03:50.120 --> 03:54.440 queue, we're going to keep within the same AF priority. 79 03:54.440 --> 03:56.720 So we need to figure out what this AF priority value is. 80 03:56.720 --> 03:57.720 Is it a 1? 81 03:57.720 --> 03:58.720 Is it a 2? 82 03:58.720 --> 03:59.720 Is it a 3? 83 03:59.720 --> 04:00.800 Or is it a 4? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 83 03:59.720 --> 04:00.800 Or is it a 4? 84 04:00.800 --> 04:03.240 Because those are our four priority values. 85 04:03.240 --> 04:07.320 And if we figure out, for example, that happens to be a 2 or a 3, well then we 86 04:07.320 --> 04:07.840 just need 87 04:07.840 --> 04:13.910 to make sure that we find the same AF3x, let's say, we just need to find the, 88 04:13.910 --> 04:15.200 what is it, 89 04:15.200 --> 04:16.960 the lowest drop probability? 90 04:16.960 --> 04:20.410 All right, so we're going to do the same process we just did here because we 91 04:20.410 --> 04:20.840 have to 92 04:20.840 --> 04:24.600 start by converting this to an AF per hot behavior. 93 04:24.600 --> 04:26.840 So I'm going to expedite this a little bit. 94 04:26.840 --> 04:28.400 We're going to take 22. 95 04:28.400 --> 04:31.680 We're going to divide it by 8 to get a whole number and remainder. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 95 04:28.400 --> 04:31.680 We're going to divide it by 8 to get a whole number and remainder. 96 04:31.680 --> 04:35.920 So that would just be 2, that's 16, with a remainder of 6. 97 04:35.920 --> 04:39.180 So 16 plus 6 should be 22, it is. 98 04:39.180 --> 04:40.440 And so that's my first number. 99 04:40.440 --> 04:46.040 Then I'm going to take this remainder, divide it by 2, and that is a 3. 100 04:46.040 --> 04:48.000 So that's interesting. 101 04:48.000 --> 04:52.320 So I've got a 2 and a 3, which means I'm in AF23. 102 04:52.320 --> 04:56.080 So I actually am in the priority field of 2. 103 04:56.080 --> 05:02.000 So the assumption here is that within this queue, we have 21, 22, and 23. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 103 04:56.080 --> 05:02.000 So the assumption here is that within this queue, we have 21, 22, and 23. 104 05:02.000 --> 05:05.440 This is typically how we do things from a real world perspective. 105 05:05.440 --> 05:08.970 If we're using our per hot behaviors, I'm going to put all of the same priority 106 05:08.970 --> 05:09.360 value 107 05:09.360 --> 05:11.000 into the same queue. 108 05:11.000 --> 05:15.540 But up here, we already have 23 as being the highest likelihood to drop a 109 05:15.540 --> 05:16.520 packet. 110 05:16.520 --> 05:20.920 So what decimal tag would keep the packet in the same queue, namely, still 111 05:20.920 --> 05:21.240 starts with 112 05:21.240 --> 05:24.720 a 2, while giving it the lowest drop priority. 113 05:24.720 --> 05:28.200 So that should be targeting AF21. 114 05:28.200 --> 05:31.520 Now notice these are not decimal values, these are per hot behaviors. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 114 05:28.200 --> 05:31.520 Now notice these are not decimal values, these are per hot behaviors. 115 05:31.520 --> 05:35.200 So I need to get to AF21 from AF23. 116 05:35.200 --> 05:37.440 Well, if I think about it, there's two ways to do this. 117 05:37.440 --> 05:40.800 I could just convert AF21 into decimal. 118 05:40.800 --> 05:43.320 That's 8x plus 2y. 119 05:43.320 --> 05:47.000 So that's 16, 8 times 2, 2 plus 1 is 2. 120 05:47.000 --> 05:48.000 There we go. 121 05:48.000 --> 05:49.000 There's 18. 122 05:49.000 --> 05:50.000 So 18 is going to be our answer. 123 05:50.000 --> 05:52.560 I could do it that way, just recognizing that. 124 05:52.560 --> 05:58.520 I could also recognize that simply going from 1 AF down to the next and down to 125 05:58.520 --> 05:59.680 the next, 126 05:59.680 --> 06:01.240 I'm just subtracting 2 each time. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 126 05:59.680 --> 06:01.240 I'm just subtracting 2 each time. 127 06:01.240 --> 06:05.760 That's all I'm doing is I'm removing 1 from the 2's column, so to speak. 128 06:05.760 --> 06:07.400 And therefore, I'm subtracting 2. 129 06:07.400 --> 06:10.200 So I start with 22, right? 130 06:10.200 --> 06:11.640 Yeah, 22. 131 06:11.640 --> 06:15.680 And so then I go to 20, and then I go to 18. 132 06:15.680 --> 06:17.960 So either way, I end up with the same answer. 133 06:17.960 --> 06:20.570 The big caveat to this is I couldn't just do that from the start, because I 134 06:20.570 --> 06:20.960 didn't 135 06:20.960 --> 06:25.220 know for sure whether I could go, you know, if this happened to be AF22, I 136 06:25.220 --> 06:25.880 could only 137 06:25.880 --> 06:26.880 go down by 1. 138 06:26.880 --> 06:31.040 I wouldn't be able to go from AF22 down to 20. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 138 06:26.880 --> 06:31.040 I wouldn't be able to go from AF22 down to 20. 139 06:31.040 --> 06:32.040 I couldn't go to. 140 06:32.040 --> 06:39.120 I had to figure out where I was in the array of AF2Xs, if that makes sense. 141 06:39.120 --> 06:42.900 But by finding out that I was AF23, I knew I could step down twice, which gets 142 06:42.900 --> 06:43.360 me from 143 06:43.360 --> 06:45.960 decimal 22 down to decimal 18. 144 06:45.960 --> 06:49.700 So that last question was more just a way to make us kind of think outside the 145 06:49.700 --> 06:50.120 box and 146 06:50.120 --> 06:52.560 make sure that we've got all this math down. 147 06:52.560 --> 06:53.800 It's not straightforward math. 148 06:53.800 --> 06:58.690 There's more of those kind of high school math era word problems where you have 149 06:58.690 --> 06:59.120 to take 150 06:59.120 --> 07:01.320 math and apply it to a real world situation. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 150 06:59.120 --> 07:01.320 math and apply it to a real world situation. 151 07:01.320 --> 07:04.240 So hopefully just a lot of fun with this math. 152 07:04.240 --> 07:07.520 I don't know if I'm the only one who says that, but this kind of math and this, 153 07:07.520 --> 07:07.760 you 154 07:07.760 --> 07:10.740 know, converting back and forth once you get that process down actually is 155 07:10.740 --> 07:11.680 pretty fun 156 07:11.680 --> 07:13.240 and pretty straightforward. 157 07:13.240 --> 07:17.080 But if any of this tripped you up, then just make up your own problems. 158 07:17.080 --> 07:21.540 Convert AF41 to decimal and then go back and check your work and make sure that 159 07:21.540 --> 07:22.040 you did 160 07:22.040 --> 07:27.110 it correctly or take a decimal value like 36 and just kind of go through it and 161 07:27.110 --> 07:27.640 the more 162 07:27.640 --> 07:30.320 we do it, the more comfortable we're going to be. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000 162 07:27.640 --> 07:30.320 we do it, the more comfortable we're going to be. 163 07:30.320 --> 07:33.290 So that brings us to the end of this skill and this review on quality of 164 07:33.290 --> 07:33.840 service. 165 07:33.840 --> 07:39.210 If any of the quiz questions or this challenge may be shown a light a little 166 07:39.210 --> 07:39.920 bit on some 167 07:39.920 --> 07:42.400 areas of weakness, that's not a bad thing. 168 07:42.400 --> 07:43.400 That's great. 169 07:43.400 --> 07:47.130 In fact, it allows us to go back and review the content as much as needed in 170 07:47.130 --> 07:47.660 order to 171 07:47.660 --> 07:50.660 shore up those knowledge gaps and make sure that we're good to go not only 172 07:50.660 --> 07:51.480 moving forward, 173 07:51.480 --> 07:56.080 but then later on when we're preparing for our exam in the last stages. 174 07:56.080 --> 07:58.840 I hope this has been informative for you and I'd like to thank you for viewing.