Time
15 hours 34 minutes
Difficulty
Intermediate
CEU/CPE
16

Video Description

Static Routing Lab For this lesson we demonstrate router 1 attempting to communicate with a 2 another sub interfaces on router 2. You'll learn how to launch and use the interface brief command to confirm the routers are up and online, and the show ip route command to confirm what network is available. We'll also dissect how to use ping, show ip interface, and debug. You'll learn what the debug command output displays, what data is important to know, and what unrouteable means.

Video Transcription

00:04
Okay. So, as you see, this is the same topology we have been using throughout our labs and same topology. I drew on the board without switch. 123 and four present.
00:16
Roger. 21 is going to try and route to these two sub interfaces on router. To
00:23
which are if I execute the show, I be interphase. Brief command
00:28
are the 10 dot Tenn dot Tenn dot to 54 $20. $20.20 dollars to 54 addresses.
00:37
Now, if we go to router to a one
00:40
maximize and check our routing table show I p
00:46
route,
00:48
you see that the only network available to router to a one at this point is the 200 network, the 202 102 100.0 slash 30 network.
00:58
And it says Little C
01:00
say it means that this network is directly connected.
01:06
The legend on top also say C stands for connected.
01:11
So if I try and
01:12
do a ping
01:15
to $10.10 dollars, 10 to 54
01:21
it does not work.
01:23
Break out of the ping by executing control shift six. That's the brake sequence. I didn't want to wait for five things to fail
01:30
If I d bug
01:33
I p. Packet. And remember, the Debo command puts the internal processing off a router on screen for you to view
01:40
not to be done in production. Once again. Do not do these commands in production.
01:46
And if I ping again,
01:49
I get a message.
01:51
Let me break out with control shift six.
01:53
It says unr out herbal.
01:57
I turned off my debugging.
02:00
So what I need
02:01
to do is put routes in my routing table.
02:07
Put routes for the 10 and the 20 Network on my routing table. The 10 and 20 network have a slash 24 mask. Let's make sure
02:15
let me show you
02:19
if I say show I p interface
02:27
Fast Ethernet
02:29
zero slash 1.10
02:32
which is different from the show Interface Command. Previously, when I was doing the command show interface facet in it
02:39
gino slash 1.10 without the keyword i p it was showing me a physical
02:46
characteristics off that interface. Now it's gonna present to me I'd be related information
02:52
since I added the keyword. I pee into the command
02:58
So
02:59
intervest faceted as you know slash 1.10 has an address of 10 9 10 9 $10 to 54 with this last 24 Mass, which is 2552552550
03:10
Let's look at interface Fascinating. It's Euros last 20.
03:14
I pull up the command using the up arrow key,
03:17
so I'm gonna execute the show I p interface. Faceted as you know, slash one doc 20
03:23
and
03:25
the address is $20.20 dollars, $20 to 54 with a slash 24 mask.
03:31
So let's go back to router to a one.
03:37
And let's create two routes to the 10 and 20 network,
03:43
so I be Route.
03:45
My destination network is 10 dot Tenn dot Tenn 10.0.0.0.
03:50
My mask is 255255255.0.
03:57
No,
03:58
I have two options.
04:00
I can either specify the next top I p address
04:04
or in this case, this guy stays over here on the C l I. It says fording routers address, which would be
04:14
the address of the next top. Routers were asked. Traffic leaves
04:16
my router One. What is the i p it encounters along this path
04:23
the next i p. It encounters is the cereal 000 i p. Address on Router one, which is
04:30
Let's look at it,
04:33
show I p interface brief,
04:38
which is 202 102 100.1 on serial 000
04:46
So
04:47
I'm going to not use the next top I pee. My other option is to simply use an exit interface.
04:57
So our exit into face in this case is a serial interface.
05:02
The serials, you know, 10 interface on router to one which faces rather one.
05:13
And then I may specify an administrative distance.
05:16
Right now, the default administrative distance. Remember the administrative distance being the trustworthiness off a routing protocol?
05:25
The default administrative distance for a static is one. So I'm just not going to say anything. I'm just gonna press one. Or I could just leave this blank and hit Enter or I could add one hair
05:36
and hit. Enter. Now I'm going to create
05:41
a static route
05:43
for the 20 network
05:45
with the I p route. $20.20 dollars, $20. 255255255.0
05:54
Cereal
05:55
010
05:58
Now
05:59
the rule of thumb is
06:02
or a good rule to follow is that you always create routes,
06:08
pointing out an exit interface when you're over a point to point link.
06:13
The reason for that is beyond the scoop of the C, C and A class. It is actually
06:17
closer to D. C, N P and C C I level stuff.
06:24
So I'm not gonna do an explanation off why you should create
06:30
a static route pointing out an exit interface on a serial on a point to point serial link. Just remember that rule and always follow it.
06:39
So when pointing routes out of a point to point link or out of a serial interface, you always use the exit interface I D. Which in this case is cereal 010
06:50
No,
06:54
I have created the to route to Metro 10 and Network 20. Let's look at these routes in our routing table.
07:00
Well, actually, what I'm going to do is bring up
07:03
the static route that I created for the 20 Network and changed the administrative distance to eight.
07:10
So the next field is the administrative distance field. Say is distance metric for this route,
07:16
I'm gonna change it to eight.
07:20
Now looks, look, ads are running config Sure
07:26
running config
07:28
and let's find the static routes by scrolling down.
07:31
And here they are
07:34
now a few things about administrative distance.
07:38
One. The default administrative distance
07:41
over static route
07:42
is one.
07:44
You don't see anything here.
07:46
That means this has a default administrative distance and the distance being one.
07:51
Cisco routers or Cisco devices often do not show defaults in the running conflict, so you will not see it one. However, you should know when you don't see anything here that this route has a default administrative distance.
08:07
However, since I changed the administrative distance for the 20 Route
08:11
28 and it is not the default it shows in my running conflict,
08:18
administrative distances can vary between zero and 255
08:22
So connected route. The original routes that we had in our routing table. If I say a show, I'd be route connected.
08:31
This is what we show saw originally, the 200 network, which is connected.
08:37
This connected network has an administrative distance or connected route, has an administrative distance off zero
08:46
static route by default, have an administrative distance off one
08:52
for the second route to the 20 network. I changed the administrative distance to eight. Hence his shows. It does not show on the first route because it is default and Cisco routers and other devices. Switches do not show defaults,
09:09
so administrative distances can vary between zero and 255 Remember that
09:15
route with administrative distances off? 255 are not installed in the routing table.
09:22
Now let's look at our static rounds in the routing table. Show I P route
09:26
or I could even say, Sure, I peer out static, but let's look at the whole routing table first. So at the bottom, hair is are connected route,
09:37
which was a 200 network which was directly connected on serial 010
09:43
Now you see something interesting.
09:45
Network 20. Well, first
09:48
you see that the little s on the left hand side,
09:52
it stands for static. So these two routes are static grounds.
09:56
Now you see something interesting. Network 10
10:01
and network 20. Sure as directly connected.
10:05
Whenever you point a route out
10:07
a direct, whenever you point a route out, often interface instead of using the next top option, that route shows up as directly connected
10:18
on a point to point link. You should always do this, and it is a good rule to follow
10:24
now, since this route shows that directly connected does this administrative distance becomes zero or it remains at
10:31
one.
10:33
The answer is that it remains at one. That's a trick question that is sometimes asked on the exam.
10:41
Just because it shows up as directly connected doesn't mean the default administrative distance changed to zero. No, it is still one.
10:50
Now let's try and ping to these
10:54
to these networks. Let's try paying the 10 dot tend not tend to 54 address, which exists on router to. So I'm trying to go from not or to a one
11:03
two here, two router to to the two addresses that exist on this interface.
11:11
Let's try that ping 10 10 $10 to 54
11:16
and I get for you,
11:18
which is destination unreachable.
11:22
It is also an ICMP type message. It is an ICMP message,
11:26
Internet control messaging protocol message and the router. Somebody is telling me that this destination is unreachable to you.
11:35
Let's go turn on debugging on Router one and router to a one,
11:41
So debug
11:43
I p I C M p
11:48
and debug
11:50
I well Let's just look at the I c m p d. Book First,
11:56
I'm going to ping from router to a one.
12:00
I'm gonna turn on my I p packet debugging debug I p packet
12:05
And then I'm gonna attempt to ping again.
12:09
Now
12:11
I'm getting a message
12:13
that says Routed y Our rib
12:16
rib stands for routing table or route information base.
12:22
So
12:22
the routing table, the word i p routing table and the word rib or route information base are synonymous. It's one of the same thing. So it's basically telling me I routed the packet out.
12:35
Let's see what happens at Router one
12:41
router one is sending me back a destination, unreachable message or a host. Unreachable message.
12:48
The host unreachable destination was $10.10 dollars, $10 to 54 but
12:54
router one sent back.
12:56
Ah, host unreachable message back to router to a one.
13:01
If I
13:05
let me turn off the ICMP debugging and said the bug
13:09
i p. Hackett and then try and ping again from router to a one.
13:16
Let's see what happens on Rather one. Now
13:22
Router One now is saying that this message is unraveled Herbal,
13:26
of course,
13:30
for
13:33
for when router to a one cent. The traffic out the ping traffic out router of one receives it.
13:39
However, if you check router ones routing table, you're trying to get to network 10 dot Tenn dot Tenn 10.0.0.0 slash
13:46
24.
13:48
If I look at rounder ones routing table,
13:52
I see that router one is unaware of the 10 Network. So of course it drops the traffic and sense router to one. A message back saying
14:01
This destination is unreachable to me.
14:05
So we need to add two routes
14:09
to Metro 10 and Metro 20 also on router one.
14:13
So I'm going to say I be route
14:18
Tenn dot Tenn dot Tenn 0.0.0.0 is just my destination network, then the destination mask.
14:28
And now,
14:30
instead of picking and interface to rout out off,
14:33
I am going to give it the next hop I p address
14:39
a good rule of thumb again. Another rule is when you're creating routes that will
14:46
needs
14:48
a multi access interface, a monthly access into Frisbee ing eternity or, in this case, fast Internet.
14:54
You always always use the next hop routers I p address, not the exit interface.
15:01
So
15:03
traffic flowing in this direction the next I P address I encounter is router twos as zero slash zero interface address,
15:13
which is Let's check
15:16
show I P interface Brief
15:20
router twos at zero slash zero interface addresses 1 51 a 1 $45 too.
15:26
So that's what I'm going to use on Router one as my next stop
15:31
i. P.
15:35
So I'm simply going to say
15:37
1 51 01
15:39
45.2
15:43
and hit Enter
15:45
and it.
15:46
The administrative distance for this route remains one,
15:50
and I also need to create a route to my 20 network i p Route $20.20 dollars, 20.0
15:58
2552552550
16:02
for a slash 24 mask and the next top I'd be remains the same.
16:07
However, I'm going to change the administrative distance here to eight Also just assure you the difference.
16:15
I look at my routes in my routing table,
16:18
show I P route,
16:22
or to get a cleaner output, since these two
16:26
are connected routes. The 200 network facing router to a one and the 1 51 1 45 network facing Router
16:34
23 and four. I want to leave this out for a cleaner output? I can actually say Sure I p route static
16:41
and just get my static routes. Now, I have a route to the $10.10 dollars $10.0 network
16:48
via
16:49
the next top I P, which is 1 51 a 1 $45 to. So I will be sending my information to this I p, which is round or two
16:59
now. This first field
17:02
in the middle of this output. This first field in the bracket
17:06
is your administrative distance.
17:07
You see, it is one for the default that we didn't change an eight
17:12
for
17:15
for the 20 route, which we change to eight.
17:18
Okay, once again, if I say sure running config and look at these routes in my running config,
17:26
the route with the default administrative distance of one does not show
17:33
the route with the non default administrative distance of eight shows the administrative distance because Cisco devices do not show defaults
17:42
now will it work? Let's find out.
17:45
Let's go to router
17:48
to a one
17:52
and try and Ping.
17:52
I'm going to turn off all possible debugging
17:56
not paying 10 dot n not end up to 54
18:03
and it's still not pinging.
18:04
So let's say debug I p I C M p
18:10
and Try and Ping again
18:15
and I don't see anything.
18:18
So what's going on?
18:19
Well, let's do a trace route.
18:22
Trace out is a function
18:25
where you can get the eyepiece between one source and one destination by doing a trace route to it.
18:32
And
18:33
every router that the trace passes through will send you back its I p address. So you will know how far you got before a problem occurred.
18:44
So I do a trace route to 10 not 10 not $10 to 54
18:49
and I'm getting
18:52
a message from outer one.
18:55
And then it's not going beyond Router one.
18:57
So let's go to one. Let's go to closer to the source of the problem
19:02
and figure out what's wrong.
19:03
I go to Roger Juan,
19:07
and I said debug
19:10
i p I c M p in a trying ping, Tenn dot Tenn dot end up to 54 again,
19:18
and I am getting an echo reply
19:22
from router to.
19:23
So what's going on here?
19:26
Well,
19:27
let's go to Router, to
19:33
which is closer, even closer to the source of the problem. Who's router? One is standing traffic to router to just fine
19:41
screwed around her to and say
19:45
debug I p packet
19:48
and then send a ping from Router two. A 12 router to
19:55
on drought or choose 10. Not 10 not 10. Not 2 54 address, which is on fast Ethan It judo slash 1.10
20:03
and now you see
20:04
router to is trying to send a message back, but it says unr out. Herbal unravel to destination. 202 102 100 too well, of course,
20:14
a ping consists often echo and an echo reply. We created routes and router to a one.
20:22
We created routes and rather to a one to send the to send the traffic to outer one.
20:26
We created routes on Router one to send the traffic all the way to router to, but router to does not know how to get to this 200 network between router to one and rather one.
20:37
If we look and a router to his routing table,
20:45
you see that router to does not have the 200 network in its routing table on Lee, the 10 Network, which is connected the 20 network, which is connected, and the 1 51 a 1 45 network, which is also connected.
21:00
So on router to
21:02
We need a route. I peer out
21:06
to the 202 102 100 0 network between
21:11
Router one and Router to one.
21:14
The mask for that network is a slashed 30 Mass, since it's a point to Point Link is 255255255252
21:22
And then once again.
21:23
Since this route is going to point out a fast Internet interface, which is a multi access link, multi access standing for more than two people can be on the network at the same time. In this case, it's rather 1234 So that makes four hosts on the network at the same time.
21:41
So I'm going to look for a next hop i p.
21:45
So traffic going this way back to Router one encounter the first I P then it will encounter is rather one F zero zero's interface address, which is
21:59
1 51 01 45.1
22:03
So now I have a route back to router
22:06
to one or
22:07
the network on which router tool one sits,
22:11
and this should now work.
22:15
So let's go to Router to one and ping the 10 10 10 to 54 address. And of course it works. If I do a trace route
22:25
to the 10 doc
22:26
Tenn dot Tenn dot to 54 address,
22:30
you see that you passed through outer one and then you reach route or two. Now,
22:36
at this point can router to a one
22:38
ping router. Three.
22:41
Let's find out.
22:45
Ping 1 51 a 1 45 got three, which is the fastest in at 00 Interface address on Router three
22:55
is the address of this interface right here.
22:57
So this network whole whole network here is 1 51 a 1 45.0 slash 29 Roger one is 10.1 Roger to his dot to rob her 3.3 and rotter Ford's 0.4 just to reiterate.
23:11
So if I try and Ping Router three. What happens?
23:15
No. Go
23:17
once again if I check my routing table,
23:22
you see that the 1 51 01 $45.0 network is not in my routing table. Hence I cannot ping router three.
23:32
Now, what if I told you
23:33
I only want you to be able to paying Router three
23:37
not router to not router for only router three.
23:44
What? What do I do?
23:45
Well,
23:45
if I created this route,
23:49
I peer out 1 51 a 1 45.0
23:56
255255255 to 48 for the slash 29 mask and then the exit interface, which is cereal 010
24:07
So once I have created this route on router to a one,
24:11
I'm going to try and paying Router
24:15
1234 on the 1 50 network.
24:18
So the each routers fast, Ethan at 00 interface. So I'm going to execute the Ping Command from conflict mode by putting the word do infront duping 1 51 01 45 dot walk
24:30
and I can Ping Router one. Why? Let's go Look at Router one.
24:40
Shou id be route
24:42
router. One knows about the 1 51 on one network,
24:45
and
24:47
the return traffic to the 200 network can be sent because the 200 network is directly connected to a router. One.
24:56
Let's go ahead and paying router to from writer to one Now up Arrow key to bring back the command changed the last out tattoo too.
25:04
And Router two is also reachable. Once again,
25:08
we go to router to and check the routing table
25:15
and I say, Sure, I'd be route
25:18
and you see that previously I already created a static route. We did it about five minutes ago back to the 200 network. So router to exist on the 1 50 network
25:30
because it is directly connected and the return traffic for the echo reply can be sent back because router to knows aboutthe 1 50 network.
25:41
Now, if I try and paying Router three
25:49
and router for you noticed, it does not work.
25:55
The reason being,
25:56
if I go to Router three
26:00
and check the routing table
26:03
show I be Route
26:06
Router three does not have a route back to the 200 network.
26:11
So if I said debug,
26:14
I p tack it on Router three
26:17
and resend the ping from router to a one
26:22
check on router three.
26:37
So if I rescind the traffic from router to a one true router three. I'm sending it to Router four by mistake
26:47
and check on Router three.
26:48
You see
26:51
under my debug I p packet. This is unraveled Herbal.
26:56
So I turned off my debugging
27:00
and I need a route back to the 200 network.
27:04
So let's go ahead and create that route back to the 200 Network. I've the route
27:11
202 102 $100 0
27:15
255.255 dot 255.252 Because that point to point link between rather one and 21 has a slash 30 mask.
27:25
Next, I'm
27:26
my traffic from Rather three is going to be leaving
27:30
a fascinating and interface. So going back, I need the next top I p, not the exit interface.
27:37
So traffic going back this way, we'll encounter the first I paedo encounter is the i p off rather 100
27:47
which is
27:52
1 51 01 45.1
27:56
I'm going to create the same route on router force at the weekend Ping router for also, since Router four also does not have a return route
28:04
to the 200 network, simply going to copy
28:12
that route off of route or three.
28:18
Look at my routing table to make sure just assure you that that route does not exist in the routing table. They're out to Network 202. Rather, four will not be able to send traffic back to router to a one
28:30
and paste that route and hit. Enter
28:33
now
28:36
from router to one, I should be able to paying Router three and writer for Also
28:41
it's a router. Three. It pings and writer for it pings.
28:48
However, I'm going to go ahead and remove that route
28:51
to the 1 50 network. I peer out 1 51 01 45.0 route
28:56
two networks. 1 50 that enabled us to ping router 1234 On the fast Internet interfaces. I'm gonna delete that route.
29:07
So I simply put a new in front of the whole command. And that takes away that route.
29:14
No.
29:15
What if I asked you?
29:18
I want a route that only pings router three
29:22
not router to not router for
29:25
but on Lee Ping's router three.
29:27
If I created this route,
29:30
this route is for the whole network. If I created this whole route, you would be able to ping router one router to router three and router. For
29:40
what If I only want to be able to ping
29:44
Router three. Well, there is a way
29:48
I say I'd be route
29:49
1 50
29:52
Not one. No one got 45. Now, instead of using a network address of 450.0,
29:59
I create the route to router threes. I p address on fast Ethan at 00
30:03
So that is 1 51 01 45.3
30:07
And
30:08
I use the mask off all to five fives and a pointed out off serial 010
30:18
This type of route to a single address with an all 255 mask is called ah host route because it is to a single host.
30:29
I checked my routing table. You show I peer out
30:33
and I see my 1 51 01
30:36
$45 3 route has a slash 32 masks.
30:41
So can I. Ping Router three duping 1 51 01 $45 3
30:48
Yes, I can. Kidnapping router to
30:51
No.
30:52
Cannot paying router four.
30:56
No
30:57
kidnapping router one.
31:00
No, not on the 1 50 link.
31:03
So
31:04
if I'm trying to ping this link,
31:07
which is on the 1 50 network
31:11
router to one cannot get to that either. Even the router one is directly connected because the route for this
31:18
this link does not exist in the routing table.
31:22
Now let's go to Router four
31:26
and take away our round back to the 200 Network.
31:32
And let's pretend
31:34
that Router four is a router for some company and router one is there I S P router or Internet service provider router.
31:44
Now, if you sat on Router four and try to create routes to all destinations on the Internet one by one,
31:52
well,
31:53
it wouldn't be a good idea
31:56
because there are millions of destinations
31:59
on on the Internet. So if you wanted to create static routes through all those destinations, you would be here forever.
32:07
Instead,
32:09
Router four can create what is called the gateway off last resort
32:15
or the default route.
32:17
So to create a default route, I say I'd be route,
32:22
and then I'm going to say for any destination.
32:25
So
32:29
the I P address that I'm going to use It's not the 200 network
32:32
because I need
32:35
a route to all destinations so any or all destinations I can substitute that with 0.0 dot zero with the mask 0.0 dot zero about zero pointing to router one.
32:52
So now
32:53
that I have created the
32:55
default route on Router four, pointing to my SP, which is rather one, I look at it in my routing table. Do show I p route and you see
33:07
this route to the 0000 slash zero network, which means any network
33:13
points back to my SP router, which is rather one or 1 51 a 1 45.1 with an administrative distance off one.
33:22
The star means Star over here means that this is a candidate default route.
33:29
And since we only have one candidate default route, it got picked to be our gateway off last resort.
33:36
So this is your static default route
33:39
now
33:40
just to test it out.
33:43
If I create a route
33:45
four out of fours host route for out of fours I p address.
33:49
You shouldn't be. Here
33:51
it is. I changed it three
33:52
to a four, so I'd be Route 1 51 1 45 dot for with the all too five fives
34:00
mask pointing out serial 010
34:02
I should be able to ping router for because Router four should be able to send me traffic back using that default route.
34:10
So Ping
34:13
1 51 a 1 $45 for
34:16
and it works.
34:19
This concludes our static routing lecture.

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Cisco CCNA

Our free, online, self-paced CCNA training teaches students to install, configure, troubleshoot and operate LAN, WAN and dial access services for medium-sized networks. You'll also learn how to describe the operation of data networks.

Instructed By

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Junaid Memon
Instructor