1
00:00:00,000 --> 00:00:03,311
[AUDIO LOGO]

2
00:00:03,311 --> 00:00:08,050

3
00:00:08,050 --> 00:00:11,450
Congratulations on
completing another skill.

4
00:00:11,450 --> 00:00:15,890
Now it's time for a review
in the form of a quiz.

5
00:00:15,890 --> 00:00:19,730
Let's jump in with
our first question.

6
00:00:19,730 --> 00:00:25,730
Type 1 external lSAs increase
the metric on the LSA

7
00:00:25,730 --> 00:00:28,430
to account for internal costs.

8
00:00:28,430 --> 00:00:29,585
True or false?

9
00:00:29,585 --> 00:00:35,080

10
00:00:35,080 --> 00:00:38,070
So for this question, we
have to look at the wording

11
00:00:38,070 --> 00:00:44,310
very carefully because
Type 1 external LSAs do

12
00:00:44,310 --> 00:00:47,760
account for internal costs.

13
00:00:47,760 --> 00:00:50,460
That part is all correct.

14
00:00:50,460 --> 00:00:53,700
The part that's a
problem is where

15
00:00:53,700 --> 00:00:58,290
it says that it increases
the metric on the LSA.

16
00:00:58,290 --> 00:01:00,870
This is the part
that's not true.

17
00:01:00,870 --> 00:01:06,330
The LSA is kept the same
through the entire network.

18
00:01:06,330 --> 00:01:10,200
What happens is the
receiving device

19
00:01:10,200 --> 00:01:16,560
then adds the metric to the
cost to the advertising router,

20
00:01:16,560 --> 00:01:20,580
and those are added
together not in the LSA

21
00:01:20,580 --> 00:01:22,380
but in the routing table.

22
00:01:22,380 --> 00:01:26,640
Therefore, that makes
this overall answer false

23
00:01:26,640 --> 00:01:29,640
because we're not keeping
the information in the LSA,

24
00:01:29,640 --> 00:01:34,170
it's being calculated and then
put into the routing table.

25
00:01:34,170 --> 00:01:38,600
Next question, if you change
auto-cost reference-bandwidth

26
00:01:38,600 --> 00:01:40,730
to 10,000.

27
00:01:40,730 --> 00:01:44,680
What would be the cost of a
gigabit ethernet interface?

28
00:01:44,680 --> 00:01:50,190

29
00:01:50,190 --> 00:01:53,450
So what we need to remember
for this question is

30
00:01:53,450 --> 00:01:55,910
the auto-cost
reference-bandwidth

31
00:01:55,910 --> 00:01:58,140
is in megabits per second.

32
00:01:58,140 --> 00:02:00,710
So essentially what that
means is that this would

33
00:02:00,710 --> 00:02:04,010
be 10,000 megabits per second.

34
00:02:04,010 --> 00:02:08,699
And of course, gigabit is
1,000 megabits per second,

35
00:02:08,699 --> 00:02:13,140
therefore number three
would be our correct answer.

36
00:02:13,140 --> 00:02:16,630
It would be a cost of 10.

37
00:02:16,630 --> 00:02:20,380
Final question, which
method of route selection

38
00:02:20,380 --> 00:02:27,350
does IOS XR use for its
Type 5 versus Type 7 LSAs?

39
00:02:27,350 --> 00:02:33,350

40
00:02:33,350 --> 00:02:37,340
So what we're really talking
about here is with the Type 5s

41
00:02:37,340 --> 00:02:41,660
these would be our E1s and E2s.

42
00:02:41,660 --> 00:02:47,660
With the Type 7s, these
would be the N1s and the N2s.

43
00:02:47,660 --> 00:02:50,030
So what this question
is really asking

44
00:02:50,030 --> 00:02:55,400
is on IOS XR which
RFC do we use when

45
00:02:55,400 --> 00:03:00,890
determining if we prefer ease
over ends or ends over ease?

46
00:03:00,890 --> 00:03:04,880
Now we can start off by
very quickly eliminating

47
00:03:04,880 --> 00:03:09,560
RFC 2101 that has
nothing to do with NSSA

48
00:03:09,560 --> 00:03:12,590
neither does RFC 7711.

49
00:03:12,590 --> 00:03:14,270
I don't even know
what those two are.

50
00:03:14,270 --> 00:03:15,920
They're just made up answers.

51
00:03:15,920 --> 00:03:21,470
Now the two RFCs that are
related to external versus NSSA

52
00:03:21,470 --> 00:03:25,850
are RFC 1587 and 3101.

53
00:03:25,850 --> 00:03:32,240
Remember the 1587 says
to prefer E over N.

54
00:03:32,240 --> 00:03:35,120
And 3101, which is
the newer method,

55
00:03:35,120 --> 00:03:38,090
says to prefer N over E.

56
00:03:38,090 --> 00:03:41,820
So the question becomes,
as of right now,

57
00:03:41,820 --> 00:03:46,430
which of these methods
is used by IOS XR.

58
00:03:46,430 --> 00:03:51,350
And unfortunately the
answer is RFC 1587.

59
00:03:51,350 --> 00:03:54,360
I say unfortunately because
it is the older method.

60
00:03:54,360 --> 00:04:00,500
However, keep in mind that NSSAs
or Not-So-Stubby Areas are not

61
00:04:00,500 --> 00:04:04,280
necessarily the focus of iOS XR.

62
00:04:04,280 --> 00:04:06,560
That would of course,
make answer three here

63
00:04:06,560 --> 00:04:08,270
an incorrect answer as well.

64
00:04:08,270 --> 00:04:13,140
That's not supported on IOS
XR, at least not right now.

65
00:04:13,140 --> 00:04:20,380
So that leaves our correct
answer as number two, RFC 1587.

66
00:04:20,380 --> 00:04:22,490
So that concludes this quiz.

67
00:04:22,490 --> 00:04:25,150
If you find that you are
missing any of the information

68
00:04:25,150 --> 00:04:27,520
here to answer
these questions, I

69
00:04:27,520 --> 00:04:29,830
would encourage you to go
back and review the reference

70
00:04:29,830 --> 00:04:32,360
sources on each question.

71
00:04:32,360 --> 00:04:37,510
Otherwise, congratulations on
completing OSPF path selection.

72
00:04:37,510 --> 00:04:39,850
I hope this has been
informative for you,

73
00:04:39,850 --> 00:04:42,960
and I'd like to thank
you for viewing.

74
00:04:42,960 --> 00:04:46,000