1
00:00:00,000 --> 00:00:00,499

2
00:00:00,499 --> 00:00:02,880
Once a network has a
dozen or so routes,

3
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it's no longer
reasonable and is kind of

4
00:00:04,800 --> 00:00:08,310
tedious, actually, to do manual
configuration of static routes.

5
00:00:08,310 --> 00:00:09,960
So we're going to
migrate or move

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to something more flexible.

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Specifically, dynamic
routing protocols.

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00:00:14,610 --> 00:00:16,620
So in this topology,
I've taken the liberty

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00:00:16,620 --> 00:00:19,140
of adding an additional
router, router 3 and also

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some additional networks.

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00:00:20,530 --> 00:00:25,110
So we've got the 10.1.0,
10.2.0, 10.3.0, 10.4.0, 10.5.0,

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00:00:25,110 --> 00:00:30,720
also 10.6.0 between R1 and
R3, 10.7.0 between R3 and R2,

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and the 10.8.0 network
hanging off of R3.

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And the benefit of using
a dynamic routing protocol

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is we can get these
devices talking

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to each other to dynamically
share information regarding

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what routes are reachable
and through whom.

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00:00:42,810 --> 00:00:44,520
And there's two
major camps regarding

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00:00:44,520 --> 00:00:45,670
dynamic routing protocols.

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There's distance vector.

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00:00:47,700 --> 00:00:51,270
The classic example of that
would be the RIP protocol--

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00:00:51,270 --> 00:00:52,450
may it rest in peace.

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00:00:52,450 --> 00:00:54,402
It stands for Routing
Information Protocol.

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And there's a couple
flavors of it.

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00:00:55,860 --> 00:00:57,570
There's version 1,
and there's version 2.

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00:00:57,570 --> 00:01:00,177
Most people are using version
2, if they're still using it.

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00:01:00,177 --> 00:01:02,010
And with a distance
vector routing protocol,

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00:01:02,010 --> 00:01:03,200
it's routing by rumor.

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00:01:03,200 --> 00:01:04,950
What do you mean,
Keith, routing by rumor?

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00:01:04,950 --> 00:01:08,550
Well, if R1 believes that he can
reach the 10.1 network and 10.2

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network, he's going to
go ahead and tell R2.

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00:01:11,182 --> 00:01:13,140
And R2 says, great, thanks
for the information.

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00:01:13,140 --> 00:01:14,730
If I need to reach those
networks or forward

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00:01:14,730 --> 00:01:16,380
packets in those
directions, I know

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00:01:16,380 --> 00:01:17,940
I can use you as the next hop.

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00:01:17,940 --> 00:01:20,230
And R2 can propagate that
information to other router.

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00:01:20,230 --> 00:01:25,680
So R2 can advertise to R3 the
networks of 10.1.0 and 10.2.0,

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even though he doesn't
have firsthand knowledge

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of those networks, he simply
heard about them from R1.

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00:01:30,870 --> 00:01:33,240
Another approach with
dynamic routing protocols

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00:01:33,240 --> 00:01:35,330
is link state routing protocols.

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00:01:35,330 --> 00:01:36,990
And with link state
routing protocols,

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we still have routers that are
directly connected to networks

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00:01:39,690 --> 00:01:42,030
except those routers
advertised the states,

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00:01:42,030 --> 00:01:43,740
the details regarding
the networks

46
00:01:43,740 --> 00:01:44,900
that they're connected to.

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00:01:44,900 --> 00:01:47,280
In one of the
protocols, called OSPF,

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00:01:47,280 --> 00:01:49,920
which is a very good example of
a link state routing protocol--

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00:01:49,920 --> 00:01:53,200
OSPF is an acronym for
Open Shortest Path First--

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00:01:53,200 --> 00:01:55,050
and with OSPF, the
routers are going

51
00:01:55,050 --> 00:01:56,480
to send that little LSAs--

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00:01:56,480 --> 00:01:58,270
link state advertisements.

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00:01:58,270 --> 00:02:00,640
In that way, R2 can take
a look at the link state

54
00:02:00,640 --> 00:02:03,460
advertisements from R1 along
with link state advertisements

55
00:02:03,460 --> 00:02:04,380
from everybody else.

56
00:02:04,380 --> 00:02:07,037
And then every router,
based on all that data,

57
00:02:07,037 --> 00:02:09,120
can make their own
calculations about the best way

58
00:02:09,120 --> 00:02:10,330
to get through the network.

59
00:02:10,330 --> 00:02:12,840
So we're not relying so much on
rumor from a neighbor regarding

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00:02:12,840 --> 00:02:15,423
everything behind that neighbor,
a link state routing protocol

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00:02:15,423 --> 00:02:19,470
is like OSPFR, more tight
more concise and more accurate

62
00:02:19,470 --> 00:02:21,034
and usually, they
converge faster.

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00:02:21,034 --> 00:02:22,950
That means if there's a
change in the network,

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00:02:22,950 --> 00:02:24,491
the entire network
will figure it out

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00:02:24,491 --> 00:02:27,660
much faster than in a distance
vector routing protocol.

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00:02:27,660 --> 00:02:29,280
And then we also
have some protocols

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00:02:29,280 --> 00:02:30,950
in this group called hybrid.

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00:02:30,950 --> 00:02:33,840
Now Cisco, a long time ago,
created a routing protocol

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00:02:33,840 --> 00:02:36,700
called EIGRP.

70
00:02:36,700 --> 00:02:38,430
And if you read
Cisco's documentation,

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00:02:38,430 --> 00:02:41,010
they're going to tell you, it's
an advanced distance vector

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00:02:41,010 --> 00:02:42,120
routing protocol.

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00:02:42,120 --> 00:02:44,520
Because it uses all of the
features of a distance vector

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00:02:44,520 --> 00:02:46,980
routing protocol,
but EIGRP also uses

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00:02:46,980 --> 00:02:50,090
mechanisms that are similar
to how a link state operates.

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00:02:50,090 --> 00:02:52,650
So it can be referred to as
an advanced distance vector

77
00:02:52,650 --> 00:02:54,192
or if you wanted to
call it a hybrid,

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00:02:54,192 --> 00:02:56,233
no one's really going to
look twice if you put it

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00:02:56,233 --> 00:02:57,570
in either of those categories.

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00:02:57,570 --> 00:03:00,810
And one of the features of
link state that EIGRP does use,

81
00:03:00,810 --> 00:03:03,450
they form like an
official neighborship--

82
00:03:03,450 --> 00:03:05,520
using that routing protocol
with their neighbors.

83
00:03:05,520 --> 00:03:06,990
And that way if
something changes,

84
00:03:06,990 --> 00:03:08,489
they can have very
quick information

85
00:03:08,489 --> 00:03:11,100
about changing the topology and
updating their routing table

86
00:03:11,100 --> 00:03:13,600
to reflect the correct routing
tables through the network.

87
00:03:13,600 --> 00:03:15,600
And one other protocol I
want to talk about here

88
00:03:15,600 --> 00:03:19,410
is BGP, the Border
Gateway Protocol.

89
00:03:19,410 --> 00:03:22,350
And that's the protocol that
we use on the internet today.

90
00:03:22,350 --> 00:03:26,070
And one interesting thing about
BGP is that BGP neighbors--

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00:03:26,070 --> 00:03:28,360
two BGP speakers that are
talking to each other--

92
00:03:28,360 --> 00:03:30,570
they don't have to
be directly connected

93
00:03:30,570 --> 00:03:31,750
or on the same network.

94
00:03:31,750 --> 00:03:34,030
So for example, we can
have a router over here.

95
00:03:34,030 --> 00:03:35,310
Let's call it router 4.

96
00:03:35,310 --> 00:03:36,866
And up here, we
can have router 5.

97
00:03:36,866 --> 00:03:38,490
And as long as they
have reachability--

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00:03:38,490 --> 00:03:40,230
meaning they have connectivity
to each other through

99
00:03:40,230 --> 00:03:41,070
the network--

100
00:03:41,070 --> 00:03:43,950
they can establish
a BGP neighborship,

101
00:03:43,950 --> 00:03:45,870
which makes it fairly
unique compared

102
00:03:45,870 --> 00:03:49,030
to distance vector or a link
state routing protocols.

103
00:03:49,030 --> 00:03:51,930
So we can put BGP if we wanted
to also in that category called

104
00:03:51,930 --> 00:03:54,990
hybrid because it has some
mechanisms that resemble

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00:03:54,990 --> 00:03:56,940
distance vector
protocols, and it also

106
00:03:56,940 --> 00:03:59,555
has things like neighborships
that are similar to how

107
00:03:59,555 --> 00:04:01,110
link state protocols operate.

108
00:04:01,110 --> 00:04:03,600
And the benefit of using a
dynamic routing protocol is

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00:04:03,600 --> 00:04:06,960
that once we have configured
the dynamic routing protocol,

110
00:04:06,960 --> 00:04:08,730
changes that are
made on the network--

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00:04:08,730 --> 00:04:11,340
links coming up or links going
down or new networks being

112
00:04:11,340 --> 00:04:12,030
added--

113
00:04:12,030 --> 00:04:14,490
all that information can
be dynamically communicated

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00:04:14,490 --> 00:04:15,930
to the other
routers, so we don't

115
00:04:15,930 --> 00:04:18,547
have to manually
configure static routes.

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00:04:18,547 --> 00:04:20,130
In this Nugget, we
took a look at some

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00:04:20,130 --> 00:04:23,670
of the categories and benefits
of dynamic routing protocols.

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00:04:23,670 --> 00:04:26,010
I hope this has been
informative for you,

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00:04:26,010 --> 00:04:29,510
and I'd like to thank
you for viewing.