1 1 00:00:00,500 --> 00:00:02,710 IP and VLAN settings. 2 2 00:00:02,710 --> 00:00:06,340 In this video, we're going to discuss IP and VLAN settings. 3 3 00:00:06,340 --> 00:00:08,870 First, let's talk about IP settings. 4 4 00:00:08,870 --> 00:00:11,620 This can occur when you have the incorrect IP address, 5 5 00:00:11,620 --> 00:00:15,000 subnet mask, gateway or DNS server IP address 6 6 00:00:15,000 --> 00:00:16,050 assigned to a client 7 7 00:00:16,050 --> 00:00:18,820 and it will cause issues for you with your IP settings. 8 8 00:00:18,820 --> 00:00:20,880 Remember from your lessons on DHCP, 9 9 00:00:20,880 --> 00:00:23,090 we talked about the fact that every network client 10 10 00:00:23,090 --> 00:00:25,010 needs four key pieces of information 11 11 00:00:25,010 --> 00:00:27,350 in order to communicate properly on the network. 12 12 00:00:27,350 --> 00:00:29,820 This is their IP address, their subnet mask, 13 13 00:00:29,820 --> 00:00:31,430 the IP of their default gateway 14 14 00:00:31,430 --> 00:00:33,480 and the IP of their DNS server. 15 15 00:00:33,480 --> 00:00:35,440 Now let's take a look at a static assignment 16 16 00:00:35,440 --> 00:00:37,170 on this OSX client. 17 17 00:00:37,170 --> 00:00:40,110 Notice here, we have three key pieces of information shown. 18 18 00:00:40,110 --> 00:00:42,080 The IP address, the subnet mask 19 19 00:00:42,080 --> 00:00:44,190 and the router or default gateway. 20 20 00:00:44,190 --> 00:00:46,420 The DNS server IP is on a different tab, 21 21 00:00:46,420 --> 00:00:48,170 and it really doesn't matter for this example, 22 22 00:00:48,170 --> 00:00:50,780 as long as we don't need to conduct name resolutions. 23 23 00:00:50,780 --> 00:00:53,060 So, you were called to troubleshoot this client 24 24 00:00:53,060 --> 00:00:54,880 because they can't access the internet. 25 25 00:00:54,880 --> 00:00:56,670 Let's assume you already tried to ping the server 26 26 00:00:56,670 --> 00:00:59,190 at 8.8.8.8 and it failed. 27 27 00:00:59,190 --> 00:01:02,160 So, you know you have some kind of a routing issue here. 28 28 00:01:02,160 --> 00:01:03,640 What could the problem be? 29 29 00:01:03,640 --> 00:01:05,770 Now, I want you to go ahead and pause the video here 30 30 00:01:05,770 --> 00:01:08,290 and look at it and see if you can figure out the issue. 31 31 00:01:08,290 --> 00:01:09,740 All right, I'm going to count to five. 32 32 00:01:09,740 --> 00:01:13,840 One, two, three, four, five. 33 33 00:01:13,840 --> 00:01:15,000 All right, you're back? 34 34 00:01:15,000 --> 00:01:16,600 Did you figure out the issue? 35 35 00:01:16,600 --> 00:01:17,460 In this case, 36 36 00:01:17,460 --> 00:01:20,030 the issue is that we have the wrong default gateway. 37 37 00:01:20,030 --> 00:01:24,650 Notice the IP address is 192.168.1.200, 38 38 00:01:24,650 --> 00:01:29,570 and it has a subnet mask of 255.255.255.0. 39 39 00:01:29,570 --> 00:01:30,960 With this subnet mask, 40 40 00:01:30,960 --> 00:01:33,110 the default gateway would have to be an IP 41 41 00:01:33,110 --> 00:01:36,590 of 192.168.1 dot something 42 42 00:01:36,590 --> 00:01:41,240 because it's in this 192.168.1.0/24 network 43 43 00:01:41,240 --> 00:01:42,830 for us to be able to reach it. 44 44 00:01:42,830 --> 00:01:44,090 Now, if the default gateway 45 45 00:01:44,090 --> 00:01:48,440 is set 10.0.1.1 and this is truly the IP of my router, 46 46 00:01:48,440 --> 00:01:50,220 then I have an incorrect IP address. 47 47 00:01:50,220 --> 00:01:55,170 Because again, my subnet mask of 255.255.255.0, 48 48 00:01:55,170 --> 00:01:58,433 if applied to the router's IP address of 10.0.1.1 49 49 00:01:58,433 --> 00:02:00,230 would tell me I need to have something 50 50 00:02:00,230 --> 00:02:04,420 in the network of 10.0.1.0/24. 51 51 00:02:04,420 --> 00:02:06,680 So to get this client to connect to the internet 52 52 00:02:06,680 --> 00:02:08,560 and have its traffic properly routed, 53 53 00:02:08,560 --> 00:02:12,127 I need to change either the default gateway to 192.168.1.1 54 54 00:02:13,810 --> 00:02:18,270 or change the IP address to 10.0.1.200 55 55 00:02:18,270 --> 00:02:19,630 or something like that. 56 56 00:02:19,630 --> 00:02:21,800 All right, let's take a look at another example. 57 57 00:02:21,800 --> 00:02:23,670 This one comes from a Windows client. 58 58 00:02:23,670 --> 00:02:25,010 Just like our last example, 59 59 00:02:25,010 --> 00:02:28,570 this client cannot ping 8.8.8.8 successfully. 60 60 00:02:28,570 --> 00:02:31,770 So you see the client has a statically assigned IP address 61 61 00:02:31,770 --> 00:02:35,110 of 192.168.1.200. 62 62 00:02:35,110 --> 00:02:39,800 Its subnet mask is 255.255.255.128 63 63 00:02:39,800 --> 00:02:43,080 and the default gateway here is 192.168.1.1. 64 64 00:02:44,500 --> 00:02:46,360 All right, go ahead and pause the video. 65 65 00:02:46,360 --> 00:02:48,230 I want to see if you can identify the issue 66 66 00:02:48,230 --> 00:02:49,750 and think about how you're going to fix 67 67 00:02:49,750 --> 00:02:51,960 this client's network connectivity issues. 68 68 00:02:51,960 --> 00:02:53,340 Pause the video and come back 69 69 00:02:53,340 --> 00:02:57,870 in one, two, three, four, five. 70 70 00:02:57,870 --> 00:02:59,090 All right, you're back? 71 71 00:02:59,090 --> 00:03:00,480 Did you figure this one out? 72 72 00:03:00,480 --> 00:03:02,770 Let's take a closer look at that subnet mask. 73 73 00:03:02,770 --> 00:03:06,657 Notice it wasn't a class full class C of 255.255.255.0 74 74 00:03:08,730 --> 00:03:13,730 So this isn't the 192.168.1.0/24 network 75 75 00:03:14,440 --> 00:03:18,160 and it doesn't have 254 usable IP addresses. 76 76 00:03:18,160 --> 00:03:23,160 Instead we have a subnet mask of 255.255.255.128. 77 77 00:03:24,510 --> 00:03:28,550 This gives us a /25 network using CIDR notation. 78 78 00:03:28,550 --> 00:03:32,470 That means we only have 126 usable IP addresses. 79 79 00:03:32,470 --> 00:03:36,847 So if our gateway is 192.168.1.1, 80 80 00:03:36,847 --> 00:03:41,847 and we have a subnet mask of 255.255.255.128, 81 81 00:03:41,850 --> 00:03:46,670 then our network ID is 192.168.1.0 82 82 00:03:46,670 --> 00:03:51,670 And our broadcast is going to be 192.168.1.127. 83 83 00:03:52,190 --> 00:03:54,210 Everything between those two ranges 84 84 00:03:54,210 --> 00:03:56,240 is going to be usable IPs. 85 85 00:03:56,240 --> 00:04:01,080 But our client was assigned 192.168.1.200. 86 86 00:04:01,080 --> 00:04:03,400 And that means it's assigned into a range 87 87 00:04:03,400 --> 00:04:04,960 that's in another network. 88 88 00:04:04,960 --> 00:04:08,060 So that IP address and gateway aren't on the same sub-net. 89 89 00:04:08,060 --> 00:04:10,090 This would explain why we can't route our traffic 90 90 00:04:10,090 --> 00:04:13,290 to the network because we can't reach our default gateway. 91 91 00:04:13,290 --> 00:04:15,010 This is going to be a problem for us. 92 92 00:04:15,010 --> 00:04:18,150 So our solution would be to change our IP address 93 93 00:04:18,150 --> 00:04:21,140 to something on the same sub-net as that default gateway, 94 94 00:04:21,140 --> 00:04:24,710 like 192.168.1.100 95 95 00:04:24,710 --> 00:04:26,240 or we could see if there's a gateway 96 96 00:04:26,240 --> 00:04:27,950 on the same sub-net as our client. 97 97 00:04:27,950 --> 00:04:29,170 This means we need a gateway 98 98 00:04:29,170 --> 00:04:33,450 with an IP address of 192.168.1.129 99 99 00:04:33,450 --> 00:04:38,090 or something between there and 192.168.1.254, 100 100 00:04:38,090 --> 00:04:42,820 because our network ID will be 192.168.1.128. 101 101 00:04:42,820 --> 00:04:47,260 and the broadcast will be 192.168.1.255 102 102 00:04:47,260 --> 00:04:50,360 if we're using the subnet mask for a /25 network 103 103 00:04:50,360 --> 00:04:54,200 of 255.255.255.128. 104 104 00:04:54,200 --> 00:04:56,320 All right, now, if you're going to connect to a website 105 105 00:04:56,320 --> 00:04:58,490 by its domain name and that isn't working, 106 106 00:04:58,490 --> 00:05:01,940 we need to look at the DNS IP server configuration. 107 107 00:05:01,940 --> 00:05:03,440 In this case, you'd want to ensure 108 108 00:05:03,440 --> 00:05:04,890 you have a working DNS server 109 109 00:05:04,890 --> 00:05:07,420 and the IP has been properly entered on the client. 110 110 00:05:07,420 --> 00:05:09,210 If you don't have your own DNS server, 111 111 00:05:09,210 --> 00:05:13,010 you can always set your DNS server's IP to 8.8.8.8 112 112 00:05:13,010 --> 00:05:15,740 which is the public DNS server hosted by Google. 113 113 00:05:15,740 --> 00:05:17,560 So here you could see the DNS server 114 114 00:05:17,560 --> 00:05:21,610 is set to 192.168.1.1 as the primary 115 115 00:05:21,610 --> 00:05:25,210 and 192.168.1.2 as the secondary. 116 116 00:05:25,210 --> 00:05:27,670 This is fine as long as the DNS servers there 117 117 00:05:27,670 --> 00:05:29,640 are running on those IP addresses. 118 118 00:05:29,640 --> 00:05:31,560 Now, if you don't have DNS servers, 119 119 00:05:31,560 --> 00:05:34,210 then you want to reconfigure those to the public DNS servers 120 120 00:05:34,210 --> 00:05:37,740 at 8.8.8.8 and 8.8.4.4, 121 121 00:05:37,740 --> 00:05:40,130 both of those are Google's DNS servers. 122 122 00:05:40,130 --> 00:05:42,590 Next let's talk about VLAN settings. 123 123 00:05:42,590 --> 00:05:44,290 Remember when it comes to VLANs 124 124 00:05:44,290 --> 00:05:46,650 you need to route the traffic between the VLANs 125 125 00:05:46,650 --> 00:05:49,580 otherwise your devices aren't going to be able to communicate. 126 126 00:05:49,580 --> 00:05:51,850 So let's pretend I have two VLANs, 127 127 00:05:51,850 --> 00:05:54,410 one called IT and one called HR, 128 128 00:05:54,410 --> 00:05:56,130 even though both IT and HR 129 129 00:05:56,130 --> 00:05:58,490 are connected to switch one and switch two physically, 130 130 00:05:58,490 --> 00:06:00,130 they can't communicate with each other 131 131 00:06:00,130 --> 00:06:03,130 until I route traffic between them using a router. 132 132 00:06:03,130 --> 00:06:05,680 Also, if you're going to have devices in the same VLAN 133 133 00:06:05,680 --> 00:06:08,010 they need to be in the same logical sub-net. 134 134 00:06:08,010 --> 00:06:09,550 So in this example, 135 135 00:06:09,550 --> 00:06:11,787 all of my clients are part of the IT VLAN, 136 136 00:06:11,787 --> 00:06:16,787 and they should be using the same sub-net of 192.168.1.0/24. 137 137 00:06:17,750 --> 00:06:21,060 And all of my HR VLAN clients should use their own sub-net 138 138 00:06:21,060 --> 00:06:25,330 something like 192.168.2.0/ 24. 139 139 00:06:25,330 --> 00:06:26,780 So let's take a look at this 140 140 00:06:26,780 --> 00:06:29,410 using a basic network logical diagram. 141 141 00:06:29,410 --> 00:06:32,810 Here, we see one IT client and one HR client. 142 142 00:06:32,810 --> 00:06:36,320 Each one is assigned an IP address in a /24 network. 143 143 00:06:36,320 --> 00:06:39,020 The IT client is assigned to the IT sub-net 144 144 00:06:39,020 --> 00:06:43,917 of 192.168.1.0/24 in VLAN 100. 145 145 00:06:43,917 --> 00:06:45,870 And the HR client is going to be assigned 146 146 00:06:45,870 --> 00:06:50,870 to 192.168.2.0/24 as it's network in VLAN 200. 147 147 00:06:51,750 --> 00:06:53,170 To simplify this topology, 148 148 00:06:53,170 --> 00:06:55,970 I left out all the other IT and HR clients, 149 149 00:06:55,970 --> 00:06:57,790 but there could be 50 or 60 of these 150 150 00:06:57,790 --> 00:07:00,550 connected there as well, either to switch one or two. 151 151 00:07:00,550 --> 00:07:02,390 It really doesn't matter for our purposes, 152 152 00:07:02,390 --> 00:07:05,010 as long as they're configured into the proper VLAN. 153 153 00:07:05,010 --> 00:07:07,260 Now, as this is a logical diagram 154 154 00:07:07,260 --> 00:07:08,690 and how we see it set up here, 155 155 00:07:08,690 --> 00:07:11,810 the IT client cannot communicate to the HR client 156 156 00:07:11,810 --> 00:07:12,950 and neither of those clients 157 157 00:07:12,950 --> 00:07:14,600 can communicate with the internet. 158 158 00:07:14,600 --> 00:07:16,050 Why is that? 159 159 00:07:16,050 --> 00:07:17,980 All right, I want you to pause the video here 160 160 00:07:17,980 --> 00:07:19,070 and I'm going to count to five 161 161 00:07:19,070 --> 00:07:21,490 and I want you to come back and give me the answer. 162 162 00:07:21,490 --> 00:07:24,920 One, two, three, four, five. 163 163 00:07:24,920 --> 00:07:25,753 All right, you're back? 164 164 00:07:25,753 --> 00:07:27,240 Did you figure out the issue? 165 165 00:07:27,240 --> 00:07:29,450 Well, this issue is all going to come down to the fact 166 166 00:07:29,450 --> 00:07:30,560 that there are no gateways 167 167 00:07:30,560 --> 00:07:33,530 for the IT or HR clients to communicate with. 168 168 00:07:33,530 --> 00:07:36,750 Notice in this logical topology, we only have one router 169 169 00:07:36,750 --> 00:07:40,660 and that router has an interface IP of 10.0.0.1 170 170 00:07:40,660 --> 00:07:44,040 in the 10.0.0.0/24 network. 171 171 00:07:44,040 --> 00:07:46,970 This means it's the default VLAN, VLAN 1 172 172 00:07:46,970 --> 00:07:49,510 and its network isn't on the same logical network 173 173 00:07:49,510 --> 00:07:51,920 as either the IT or HR VLANs. 174 174 00:07:51,920 --> 00:07:55,630 So for us to allow the IT and HR clients to communicate, 175 175 00:07:55,630 --> 00:07:57,570 they're going to need a place to route traffic 176 176 00:07:57,570 --> 00:07:59,730 between switch one and switch two. 177 177 00:07:59,730 --> 00:08:02,420 Then to allow both of them to communicate with the internet, 178 178 00:08:02,420 --> 00:08:04,220 we need to connect them to a new router 179 179 00:08:04,220 --> 00:08:06,220 that's connected to the internet as well. 180 180 00:08:06,220 --> 00:08:08,630 Now our easiest and cheapest solution in this case 181 181 00:08:08,630 --> 00:08:09,930 would be to remove the connection 182 182 00:08:09,930 --> 00:08:12,070 between switch one and switch two. 183 183 00:08:12,070 --> 00:08:14,900 Then we can connect switch one to router one 184 184 00:08:14,900 --> 00:08:16,480 and assign it a new interface 185 185 00:08:16,480 --> 00:08:18,830 on an IP address in the IT VLAN. 186 186 00:08:18,830 --> 00:08:21,200 We could also connect switch two directly to router one 187 187 00:08:21,200 --> 00:08:24,050 and assign it an interface with the HR VLAN. 188 188 00:08:24,050 --> 00:08:28,330 Now we can use router one to route traffic between VLAN 100, 189 189 00:08:28,330 --> 00:08:31,610 the IT VLAN and VLAN 200, the HR VLAN. 190 190 00:08:31,610 --> 00:08:34,680 And we can route both of those VLANs out to the internet, 191 191 00:08:34,680 --> 00:08:36,640 going through router one as well. 192 192 00:08:36,640 --> 00:08:39,300 So remember, if you start having devices 193 193 00:08:39,300 --> 00:08:40,950 that can't communicate with each other, 194 194 00:08:40,950 --> 00:08:42,870 like one of the IT clients can't communicate 195 195 00:08:42,870 --> 00:08:44,290 with one of the HR clients, 196 196 00:08:44,290 --> 00:08:46,980 it could be an improper VLAN configuration. 197 197 00:08:46,980 --> 00:08:48,820 Make sure you check your configuration 198 198 00:08:48,820 --> 00:08:50,210 and that there's a proper routing setup 199 199 00:08:50,210 --> 00:08:51,490 between the different VLANs 200 200 00:08:51,490 --> 00:08:53,400 because the number one cause of issues 201 201 00:08:53,400 --> 00:08:55,550 when you're dealing with VLANs that won't communicate 202 202 00:08:55,550 --> 00:08:58,100 is people aren't routing the traffic right. 203 203 00:08:58,100 --> 00:09:00,460 Another common mistake people make when dealing with VLANs 204 204 00:09:00,460 --> 00:09:02,220 is simply that they don't use them. 205 205 00:09:02,220 --> 00:09:03,640 Now, if you don't use VLANs 206 206 00:09:03,640 --> 00:09:07,400 all of your traffic will end up in the default VLAN, VLAN 1. 207 207 00:09:07,400 --> 00:09:08,320 When this occurs, 208 208 00:09:08,320 --> 00:09:11,360 you're going to have a really large single broadcast domain. 209 209 00:09:11,360 --> 00:09:12,200 For example, 210 210 00:09:12,200 --> 00:09:14,420 if you have a server that's operating in VLAN 1 , 211 211 00:09:14,420 --> 00:09:15,690 the default VLAN, 212 212 00:09:15,690 --> 00:09:17,390 it can experience slow load times 213 213 00:09:17,390 --> 00:09:20,320 because there's too many devices located inside VLAN 1 214 214 00:09:20,320 --> 00:09:21,590 and the number of broadcasts 215 215 00:09:21,590 --> 00:09:23,900 are going to slow down the entire VLAN. 216 216 00:09:23,900 --> 00:09:27,270 Instead, this server, which currently has an untagged port, 217 217 00:09:27,270 --> 00:09:29,820 and therefore it's assigned to VLAN 1 by default, 218 218 00:09:29,820 --> 00:09:32,900 should be added to the server VLAN with the other servers. 219 219 00:09:32,900 --> 00:09:35,360 This will segregate them from all the other client villains 220 220 00:09:35,360 --> 00:09:37,260 and increase their speed dramatically.