1
00:00:00,000 --> 00:00:00,690

2
00:00:00,690 --> 00:00:01,920
So here's our game plan.

3
00:00:01,920 --> 00:00:04,800
Let's go ahead and configure
some specific static routes

4
00:00:04,800 --> 00:00:06,690
starting on R1.

5
00:00:06,690 --> 00:00:12,450
So on R1, let's train R1 that
to get to the 10.4.0 network,

6
00:00:12,450 --> 00:00:15,150
it should use R2
as its next hop.

7
00:00:15,150 --> 00:00:18,570
Let's also configure R1 that
if it needs to forward packets

8
00:00:18,570 --> 00:00:23,630
to the 10.5.0 network, it should
also use R2 as its next stop.

9
00:00:23,630 --> 00:00:26,520
R2 needs to also be
able to forward packets.

10
00:00:26,520 --> 00:00:29,640
So in R2, we could create
some specific routes as well--

11
00:00:29,640 --> 00:00:33,660
on how to reach 10.1.0
or we could go ahead

12
00:00:33,660 --> 00:00:39,010
and use a static default route,
which basically says dear

13
00:00:39,010 --> 00:00:41,470
Mr. R2, if you get a
packet for a network

14
00:00:41,470 --> 00:00:43,600
and you don't know how
to reach that network,

15
00:00:43,600 --> 00:00:45,740
go ahead and use
your default route.

16
00:00:45,740 --> 00:00:48,340
So let's begin by taking a
look at the routing tables

17
00:00:48,340 --> 00:00:51,016
on these routers before
we add any new configs.

18
00:00:51,016 --> 00:00:53,390
And to do that, on a Cisco
router, we can use the command

19
00:00:53,390 --> 00:00:54,952
show ip route.

20
00:00:54,952 --> 00:00:57,160
And I'm going to send that
command to both the router

21
00:00:57,160 --> 00:00:58,810
1 and router 2, and
then we can go ahead

22
00:00:58,810 --> 00:00:59,810
and look at the results.

23
00:00:59,810 --> 00:01:01,090
So here on router 1--

24
00:01:01,090 --> 00:01:03,800
router 1 is directly
connected to the 10.1.0

25
00:01:03,800 --> 00:01:08,530
network and the 10.2.0 network
and the 10.3.0 network.

26
00:01:08,530 --> 00:01:10,930
And this last 24,
immediately following,

27
00:01:10,930 --> 00:01:14,080
represents that these first
three numbers, of 10.1.0,

28
00:01:14,080 --> 00:01:15,940
represents the actual network.

29
00:01:15,940 --> 00:01:17,530
We'll cover more
about that detail

30
00:01:17,530 --> 00:01:19,700
in separate IPv4 Nuggets.

31
00:01:19,700 --> 00:01:22,810
So R1 is directly connected
to those three networks.

32
00:01:22,810 --> 00:01:23,470
Fantastic.

33
00:01:23,470 --> 00:01:25,720
Let's take a look at router 2.

34
00:01:25,720 --> 00:01:27,100
So here on router 2--

35
00:01:27,100 --> 00:01:31,030
router 2 is directly connected
to 10.3 network, the 10.4

36
00:01:31,030 --> 00:01:33,950
network, and the 10.5 network.

37
00:01:33,950 --> 00:01:36,610
So let's start our
configuration back on R1

38
00:01:36,610 --> 00:01:39,836
starting from the left
going to the right.

39
00:01:39,836 --> 00:01:42,210
And on the Cisco router, we'll
go into configuration mode

40
00:01:42,210 --> 00:01:45,990
by typing in configure space
terminal or for short configt.

41
00:01:45,990 --> 00:01:47,790
And then, we'll have
the command-- ip route

42
00:01:47,790 --> 00:01:52,110
10.4.0, space, then 255
repeated three times

43
00:01:52,110 --> 00:01:55,380
followed by a zero,
space, then 10.3.0.2.

44
00:01:55,380 --> 00:01:56,844
Now let's decode what that is.

45
00:01:56,844 --> 00:01:58,260
What we're saying
to the router is

46
00:01:58,260 --> 00:02:03,120
we're adding an IPv4 route
to reach the 10.4.0 network.

47
00:02:03,120 --> 00:02:06,190
And these first three
groupings that say 255.

48
00:02:06,190 --> 00:02:06,690
255.

49
00:02:06,690 --> 00:02:10,919
255, that's very much like
this option here-- slash 24.

50
00:02:10,919 --> 00:02:12,330
It means to the
router that we're

51
00:02:12,330 --> 00:02:15,000
focusing on the
first three numbers

52
00:02:15,000 --> 00:02:17,280
in this IP address
that are representing

53
00:02:17,280 --> 00:02:20,110
the network that we are
creating the static route for.

54
00:02:20,110 --> 00:02:21,540
And this instruction
further says,

55
00:02:21,540 --> 00:02:25,170
that if you need to ever
forward a packet to 10.4.0.

56
00:02:25,170 --> 00:02:27,390
anything, the next
hop you can use

57
00:02:27,390 --> 00:02:31,569
is your good buddy, R2 at
the IP address of 10.3.0.2.

58
00:02:31,569 --> 00:02:33,360
So that one static
route teaches the router

59
00:02:33,360 --> 00:02:35,290
how to reach the 10.4.0 network.

60
00:02:35,290 --> 00:02:38,367
But we have one more-- it's
the 10.5.0 that R1 also

61
00:02:38,367 --> 00:02:39,450
needs to be able to reach.

62
00:02:39,450 --> 00:02:41,610
So we need to go ahead
and hit the upper row key.

63
00:02:41,610 --> 00:02:46,140
And we'll go back and change
out the 10.4.0 to a 10.5.0

64
00:02:46,140 --> 00:02:47,130
and press Enter.

65
00:02:47,130 --> 00:02:50,110
And now we've just
entered two static routes.

66
00:02:50,110 --> 00:02:52,770
So now, if we issue the
command, show ip route,

67
00:02:52,770 --> 00:02:54,690
we have two new static
routes right here--

68
00:02:54,690 --> 00:02:58,680
that basically say to
get to 10.4.0 or 10.5.0,

69
00:02:58,680 --> 00:03:01,260
I'm going to go ahead and
use the next hop of 10.3.0.2,

70
00:03:01,260 --> 00:03:02,550
which is R2.

71
00:03:02,550 --> 00:03:05,610
Next, let's go ahead and
configure a static route on R2,

72
00:03:05,610 --> 00:03:08,190
so that it knows how to forward
packets in the direction

73
00:03:08,190 --> 00:03:11,130
of the 10.1 or 10.2
networks if it needs to.

74
00:03:11,130 --> 00:03:12,600
So we'll go back to router 2.

75
00:03:12,600 --> 00:03:15,300
And here on router 2, we'll go
back into configuration mode.

76
00:03:15,300 --> 00:03:17,670
And let's do an example
of a default route.

77
00:03:17,670 --> 00:03:21,740
It goes something like
this-- ip route 0000.

78
00:03:21,740 --> 00:03:23,490
That represents a
default route, and we're

79
00:03:23,490 --> 00:03:26,367
going to follow it by another
set of quad zeros like this.

80
00:03:26,367 --> 00:03:28,950
And then, we're going to specify
the next hop for this default

81
00:03:28,950 --> 00:03:29,560
route.

82
00:03:29,560 --> 00:03:32,850
And that next hop is going to
be Mr. R1 in our topology, which

83
00:03:32,850 --> 00:03:34,870
is 10.3.0.1.

84
00:03:34,870 --> 00:03:36,110
We'll press Enter.

85
00:03:36,110 --> 00:03:39,120
We'll end to get out
of configuration mode.

86
00:03:39,120 --> 00:03:42,397
And let's do a show
ip route once again.

87
00:03:42,397 --> 00:03:43,230
So here's the logic.

88
00:03:43,230 --> 00:03:45,780
If an IP router
receives an IP packet,

89
00:03:45,780 --> 00:03:48,630
the router looks at the
layer 3 information,

90
00:03:48,630 --> 00:03:50,250
looks at the
destination, and then

91
00:03:50,250 --> 00:03:51,630
looks at its routing table.

92
00:03:51,630 --> 00:03:54,570
So if R2 received a packet
that had a destination IP

93
00:03:54,570 --> 00:03:58,470
address of 10.1.0.55,
router 2 is

94
00:03:58,470 --> 00:04:00,690
looking at its routing table.

95
00:04:00,690 --> 00:04:01,410
That's not it.

96
00:04:01,410 --> 00:04:03,190
That's not it.

97
00:04:03,190 --> 00:04:04,260
None of those are it.

98
00:04:04,260 --> 00:04:06,210
It's going to use
the default route.

99
00:04:06,210 --> 00:04:07,560
And because we have
that static route there,

100
00:04:07,560 --> 00:04:09,601
that's also why we have
this message right here--

101
00:04:09,601 --> 00:04:12,280
the Gateway of last resort, when
you don't know what else to do,

102
00:04:12,280 --> 00:04:14,655
go ahead and forward the packet
to the next hop that owns

103
00:04:14,655 --> 00:04:16,529
the IP address of 10.3.0.1.

104
00:04:16,529 --> 00:04:18,880
And now it's his
problem or her problem.

105
00:04:18,880 --> 00:04:20,459
So next, let's go
ahead and test this

106
00:04:20,459 --> 00:04:25,860
by doing a ping from PC1,
who's at 10.1.0.11 and let's

107
00:04:25,860 --> 00:04:31,230
ping it out 10.5.0.55, which
is a PC down on the 10.5.0

108
00:04:31,230 --> 00:04:32,760
network, and we'll press Enter.

109
00:04:32,760 --> 00:04:35,610
And because R1 and
R2 both know how

110
00:04:35,610 --> 00:04:38,400
to route based on the
static routes that we added,

111
00:04:38,400 --> 00:04:42,030
we have full connectivity
between a PC on the 10.1.0

112
00:04:42,030 --> 00:04:45,850
network and a PC on
the 10.5.0 network.

113
00:04:45,850 --> 00:04:47,940
I hope this has been
informative for you,

114
00:04:47,940 --> 00:04:51,380
and I'd like to thank
you for viewing.

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00:04:51,380 --> 00:04:52,178