1
00:00:11,060 --> 00:00:19,280
This is one of multiple IP addressing and subnetting scenarios rather than just working out the subnets

2
00:00:19,370 --> 00:00:21,130
for a scenario.

3
00:00:21,230 --> 00:00:28,340
We're gonna work them out and then configure the devices so that we can practically design and configure

4
00:00:28,760 --> 00:00:30,520
a Cisco IP network.

5
00:00:30,710 --> 00:00:35,150
So we've successfully configured this subnet.

6
00:00:35,150 --> 00:00:40,830
Now we need to configure this subnet and this gets a little bit more interesting because it's 192

7
00:00:40,850 --> 00:00:44,620
168 1 64 slice 26.

8
00:00:45,200 --> 00:00:48,160
So we already know what the subnet address is.

9
00:00:48,200 --> 00:00:51,660
Now we need to work out what the first host address is. 

10
00:00:51,740 --> 00:00:55,040
So what is the first host for this network?

11
00:00:58,110 --> 00:00:59,940
Now to work out to the first host.

12
00:00:59,970 --> 00:01:06,680
You make the host portion zeros except for the last bit which is set to 1.

13
00:01:07,170 --> 00:01:14,960
But to work out the decimal value over here you need to look at the entire octet.

14
00:01:15,000 --> 00:01:21,770
So this is 64 because that's the network plus one is 65.

15
00:01:22,220 --> 00:01:24,600
So the first host is 65.

16
00:01:25,100 --> 00:01:27,230
What is the last host.

17
00:01:27,290 --> 00:01:34,890
The easiest way to work that out actually is to do broadcast first and then work out the last host.

18
00:01:34,920 --> 00:01:44,790
So for the broadcast what we do is we fill the host portion with binary ones.

19
00:01:44,900 --> 00:01:46,290
So what is that?

20
00:01:48,280 --> 00:01:55,460
It's 255 less 128 which is 127.

21
00:01:56,190 --> 00:02:01,360
So the broadcast address is 192 168 1 127.

22
00:02:01,410 --> 00:02:08,850
Now the last host is one less than the broadcast address.

23
00:02:08,970 --> 00:02:16,960
So for the last host, we set the host portion to binary ones except for the last bit.

24
00:02:17,210 --> 00:02:22,880
So what does that equal to, that's equal to 126.

25
00:02:22,890 --> 00:02:28,920
So let's assume that we configure the router with the last IP address in the subnet and then we're going

26
00:02:28,920 --> 00:02:35,360
to enable DCHP on the router to allocate IP addresses to the hosts.

27
00:02:35,450 --> 00:02:42,900
So here's router 2, on the fast ethernet interface I'm gonna no shut the interface and then I'm

28
00:02:42,900 --> 00:02:50,430
gonna configure an IP address as we worked out 192 168 1 126

29
00:02:50,610 --> 00:02:57,210
And then we need to specify the subnet mask 255 255 255 192, so can we ping 

30
00:03:00,660 --> 00:03:01,530
our local address?

31
00:03:01,530 --> 00:03:03,780
Yes, we can.

32
00:03:03,780 --> 00:03:07,740
Now for host allocation let's use DHCP.

33
00:03:08,220 --> 00:03:17,440
So we'll create a DHCP pool with a name, New York and here we need to specify the network.

34
00:03:17,460 --> 00:03:22,360
So what is the network? It's 192 168 1 64

35
00:03:22,890 --> 00:03:29,260
And here we have an option we can either use slash 26 or the dotted decimal notation.

36
00:03:29,760 --> 00:03:40,420
So let's use CIDR or slash 26, do show run will allow us to see our configuration.

37
00:03:40,420 --> 00:03:44,350
So that's what we've done in the DHCP pool.

38
00:03:44,370 --> 00:03:47,080
Now we need to configure a default gateway.

39
00:03:47,360 --> 00:03:52,740
So our default gateway is gonna be 192 168 1 126.

40
00:03:52,920 --> 00:03:59,190
There are other options that we can specify in DHCP such as DNS server.

41
00:03:59,820 --> 00:04:05,530
And in this case, let's set the DNS server to the local router in the real world you probably have a

42
00:04:05,530 --> 00:04:07,280
separate DNS server.

43
00:04:07,870 --> 00:04:08,590
So show run

44
00:04:11,890 --> 00:04:19,279
there's the DHCP pool that we've configured we've configured the default gateway or default router and

45
00:04:19,279 --> 00:04:24,800
DNS server, now in the hosts

46
00:04:24,900 --> 00:04:26,700
let's see if they get IP addresses.

47
00:04:29,520 --> 00:04:36,260
So on the hosts we're gonna configure them to use DHCP rather than static IP addresses.

48
00:04:36,750 --> 00:04:44,830
So let's do that on both hosts or both PCs.

49
00:04:45,050 --> 00:04:47,200
Change them to use DHCP.

50
00:04:47,660 --> 00:04:54,130
And then let's start them up and let's see if they get an IP address from the DHCP server.

51
00:04:55,160 --> 00:04:57,590
Open up a console to both of them.

52
00:04:57,680 --> 00:05:05,680
So here you can see the first host got an IP address 192 168 1 65.

53
00:05:05,860 --> 00:05:11,200
And the second host got an IP address of 192 168 1 66.

54
00:05:11,200 --> 00:05:13,750
So can the second host ping the first host?

55
00:05:13,810 --> 00:05:15,950
Yes, it can.

56
00:05:16,310 --> 00:05:20,520
Will it be able to ping the default gateway.

57
00:05:20,560 --> 00:05:22,060
Let's try that.

58
00:05:22,720 --> 00:05:24,040
Yes, it can.

59
00:05:24,700 --> 00:05:32,410
So we've successfully configured the New York site with an IP address on the default gateway and we've

60
00:05:32,410 --> 00:05:34,530
set up a DHCP.

61
00:05:34,540 --> 00:05:41,390
Now one thing you wanna do when you set up a DHCP pool like this is specify the excluded address.

62
00:05:41,560 --> 00:05:49,130
We don't want the DHCP server to allocate its own address so we can use the command IP DHCP server

63
00:05:52,310 --> 00:05:55,990
or rather IP DHCP excluded address.

64
00:05:56,510 --> 00:06:04,910
And we can specify a range of addresses to exclude and this example will only exclude the local routers

65
00:06:04,970 --> 00:06:12,810
IP address so we excluded the local routers IP address which means that it won't be allocated through

66
00:06:12,810 --> 00:06:14,580
DHCP.

67
00:06:14,940 --> 00:06:20,520
I'll save the routers configuration and while we're here let's save router 1s configuration.

68
00:06:23,080 --> 00:06:27,300
OK, so at this point we've configured both San Francisco and New York.

69
00:06:27,430 --> 00:06:31,050
The next step is to configure the WAN connection.

70
00:06:31,060 --> 00:06:38,950
Now it's inefficient to use a subnet that supports 62 hosts for a network that only requires two.

71
00:06:39,640 --> 00:06:44,910
But for now, let's start off by using the subnet that we allocated.

72
00:06:45,460 --> 00:06:51,500
And then in a subsequent video, I'll show you how to optimize this, so on router 1

73
00:06:51,750 --> 00:06:57,120
let's allocate the first IP address in the subnet to the router.

74
00:06:57,400 --> 00:07:02,670
So that's essentially one more than the subnet address.

75
00:07:02,830 --> 00:07:07,990
So 129 and one more than that

76
00:07:10,430 --> 00:07:11,410
would be 130

77
00:07:14,870 --> 00:07:25,250
with our subnet mask so what you'll notice is the first IP address is one more than the subnet address and

78
00:07:25,250 --> 00:07:33,750
the last IP address is one less than the broadcast address so we need to no shut these two interfaces

79
00:07:34,560 --> 00:07:42,340
and what should happen now is router 1 should be able to ping router 2 which it can.

80
00:07:42,820 --> 00:07:50,330
So we've successfully configured the IP addresses on the WAN and on both LAN interfaces but to enable

81
00:07:50,330 --> 00:07:54,480
full connectivity in this network we need to run a routing protocol.

82
00:07:54,980 --> 00:08:04,850
And in this example, I'll run EIGRP and enable the EIGRP on network 192 168 1.0

83
00:08:04,910 --> 00:08:08,780
Now that is a class full network.

84
00:08:08,780 --> 00:08:17,720
In other words, it's looking at class C 192 168 1.0 and not to the subnet addresses on the side

85
00:08:17,720 --> 00:08:19,560
we'll do something similar.

86
00:08:19,650 --> 00:08:22,530
Network 192 168 1.0, I'll

87
00:08:22,610 --> 00:08:30,740
disable automatic summarization so that they don't automatically summarize any network's show IP EI

88
00:08:30,760 --> 00:08:36,630
GRP neighbor, notice a neighbor relationship is established to router 2

89
00:08:37,070 --> 00:08:38,780
and we should see something similar here.

90
00:08:38,780 --> 00:08:45,980
Show IP EIGRP neighbor, neighbor relationship is established to router 1 show IP route.

91
00:08:46,460 --> 00:08:54,130
Notice router 1 has 192 168 1.0 directly connected on fast

92
00:08:54,140 --> 00:09:02,950
ethernet 00 and 192 168 1 128 directly connected to serial to slash 0.

93
00:09:02,960 --> 00:09:04,700
Those are the two subnets.

94
00:09:04,700 --> 00:09:14,700
It's also learnt about network 192 168 1 64 from 192 168 1 130.

95
00:09:14,700 --> 00:09:22,100
In other words router 2, in the same way router 2 has 192 168 1 64 directly connected to fast

96
00:09:22,110 --> 00:09:30,720
Ethernet 0 slash 0 and 192 168 1 128 is directly connected to serial 2 slash 0.

97
00:09:30,920 --> 00:09:37,280
This router has learnt about a network through EIGRP from 192 168 1 129.

98
00:09:37,280 --> 00:09:44,570
In other words router 1 and it's learnt about network 192 168 1.0 so router 1 at this point should be able

99
00:09:44,570 --> 00:09:51,580
to ping PC 3 and PC 4, and the ping succeed.

100
00:09:52,650 --> 00:09:59,380
Now, if you remember PC 3 was allocated this IP address and we can confirm that by using the command

101
00:09:59,510 --> 00:10:06,470
IF config Ethernet0 is the IP address of PC 3, PC 4 IF config

102
00:10:06,510 --> 00:10:07,880
Eth 0

103
00:10:07,950 --> 00:10:20,360
There's the IP address of PC 4, so router 1 is able to ping both the PCs, now can PC one ping those

104
00:10:20,410 --> 00:10:25,450
PCs. So can we ping 192 168 1 65?

105
00:10:25,660 --> 00:10:26,900
Yes, we can.

106
00:10:27,130 --> 00:10:29,180
And 66? Yes, we can.

107
00:10:29,500 --> 00:10:35,010
Let's trace to 192 168 1 65.

108
00:10:35,070 --> 00:10:38,600
Notice the trace goes to 192 168 1

109
00:10:38,680 --> 00:10:42,660
62, router 1.

110
00:10:42,750 --> 00:10:51,090
Then it goes to 192 168 1 130 which is router 2 on the serial subnet and then it goes to 192 16

111
00:10:51,090 --> 00:10:55,570
8 165, which is PC 3.

112
00:10:55,590 --> 00:10:56,110
Be careful.

113
00:10:56,130 --> 00:10:59,220
These are separate subnets.

114
00:10:59,220 --> 00:11:04,660
These hosts are in different subnets, so that was an example of subnetting.

115
00:11:04,890 --> 00:11:11,680
We took a network, we created subnets, we worked out the subnet address, first host address, last host

116
00:11:11,680 --> 00:11:17,910
address and broadcast the address and we configured the network accordingly and then we tested that

117
00:11:17,910 --> 00:11:19,290
it worked.

118
00:11:19,290 --> 00:11:24,240
That was a simple example of a practical implementation of subnetting but it's really important that

119
00:11:24,240 --> 00:11:26,200
you know how to subnet.

120
00:11:26,210 --> 00:11:27,520
I hope you enjoyed this video.

121
00:11:27,660 --> 00:11:32,300
If you did please like it and please subscribe to my YouTube channel.

122
00:11:32,310 --> 00:11:33,930
I wish you all the very best.