Lab - Designing and Implementing a Subnetted
IPv4 Addressing Scheme
Topology
Addressing Table
|
Device
|
Interface
|
IP Address
|
Subnet Mask
|
Default Gateway
|
|
R1
|
G0/0
|
192.168.0.1/27
|
255.255.255.224
|
N/A
|
|
|
G0/1
|
192.168.0.33/27
|
255.255.255.224
|
N/A
|
|
|
Lo0
|
192.168.0.65/27
|
255.255.255.224
|
N/A
|
|
|
Lo1
|
192.168.0.97/27
|
255.255.255.224
|
N/A
|
|
S1
|
VLAN 1
|
N/A
|
N/A
|
N/A
|
|
PC-A
|
NIC
|
192.168.0.34/27
|
255.255.255.224
|
192.168.0.62
|
|
PC-B
|
NIC
|
192.168.0.2/27
|
255.255.255.224
|
192.168.0.30
|
Objectives
Part 1: Design a Network Subnetting
Scheme
Part 2: Configure the Devices
Part 3: Test and Troubleshoot the
Network
Background / Scenario
In this lab, starting from a single network
address and network mask, you will subnet the network into multiple subnets. The
subnet scheme should be based on the number of host computers required in each
subnet, as well as other network considerations, like future network host expansion.
After you have created a subnetting
scheme and completed the network diagram by filling in the host and interface
IP addresses, you will configure the host PCs and router interfaces, including
loopback interfaces. The loopback interfaces are created to simulate additional
LANs attached to router R1.
After the network devices and host PCs have
been configured, you will use the ping
command to test for network connectivity.
This lab provides minimal assistance with
the actual commands necessary to configure the router. However, the required
commands are provided in Appendix A. Test your knowledge by trying to configure
the devices without referring to the appendix.
Note: The routers used with CCNA hands-on labs
are Cisco 1941 Integrated Services Routers (ISRs) with Cisco IOS Release 15.2(4)M3
(universalk9 image). The switches used are Cisco Catalyst 2960s with Cisco IOS Release
15.0(2) (lanbasek9 image). Other routers, switches and Cisco IOS versions can
be used. Depending on the model and Cisco IOS version, the commands available
and output produced might vary from what is shown in the labs. Refer to the
Router Interface Summary Table at this end of the lab for the correct interface
identifiers.
Note: Make sure that the routers and switches have been erased and have
no startup configurations. If you are unsure, contact your instructor.
Required Resources
·
1 Router (Cisco 1941 with Cisco
IOS Release 15.2(4)M3 universal image or comparable)
·
1 Switch (Cisco 2960 with Cisco
IOS Release 15.0(2) lanbasek9 image or comparable)
·
2 PCs (Windows 7 or 8 with
terminal emulation program, such as Tera Term)
·
Console cables to configure the
Cisco IOS devices via the console ports
·
Ethernet cables as shown in the
topology
Note: The Gigabit Ethernet interfaces on Cisco 1941 routers are
autosensing. An Ethernet straight-through cable may be used between the router
and PC-B. If using another Cisco router model, it may be necessary to use an
Ethernet crossover cable.
Part 1:
Design a Network Subnetting
Scheme
Step 1:
Create a subnetting scheme that
meets the required number of subnets and required number of host addresses.
In this scenario, you are a network
administrator for a small subdivision within a larger company. You must create
multiple subnets out of the 192.168.0.0/24 network address space to meet the
following requirements:
·
The first subnet is the
employee network. You need a minimum of 25 host IP addresses.
·
The second subnet is the
administration network. You need a minimum of 10 IP addresses.
·
The third and fourth subnets
are reserved as virtual networks on virtual router interfaces, loopback 0 and
loopback 1. These virtual router interfaces simulate LANs attached to R1.
·
You also need two additional
unused subnets for future network expansion.
Note: Variable length subnet masks will not be used. All of the device subnet
masks will be the same length.
Answer the following questions to help
create a subnetting scheme that meets the stated network requirements:
1)
How many host addresses
are needed in the largest required subnet? _______25 host addresses ______________
2)
What is the minimum number of
subnets required? ____________6 subnets required _____________________
3)
The network that you are tasked
to subnet is 192.168.0.0/24. What is the /24 subnet mask in binary?
__255.255.255.0 11111111.11111111.11111111.00000000 ______________________________________________________________________________
4)
The subnet mask is made up of
two portions, the network portion, and the host portion. This is represented in
the binary by the ones and the zeros in the subnet mask.
In the network mask, what do the ones represent? ______First represent the network
portion __________________________________
In the network mask, what do the zeros represent? _______Zero represent the host portion
________________________________
5)
To subnet a network, bits from
the host portion of the original network mask are changed into subnet bits. The
number of subnet bits defines the number of subnets. Given each of the possible
subnet masks depicted in the following binary format, how many subnets and how
many hosts are created in each example?
Hint: Remember that the
number of host bits (to the power of 2) defines the number of hosts per subnet
(minus 2), and the number of subnet bits (to the power of two) defines the number
of subnets. The subnet bits (depicted in bold type face) are the bits that have
been borrowed beyond the original network mask of /24. The /24 is the slash prefix
notation and corresponds to a dotted decimal mask of 255.255.255.0.
(/25) 11111111.11111111.11111111.10000000
Dotted decimal subnet mask equivalent: ___255.255.255.128_____________________________
Number of subnets? __2^1=2______________, Number of hosts? ___128 host. 2^7-2=126 hosts per subnet _____________
(/26)
11111111.11111111.11111111.11000000
Dotted decimal subnet mask equivalent: ___255.255.255.192_____________________________
Number of subnets? __2^2=4______________, Number of hosts? __2^6-2=62 hosts per subnet ______________
(/27)
11111111.11111111.11111111.11100000
Dotted decimal subnet mask equivalent: ___255.255.255.224_____________________________
Number of subnets? __2^3=8______________ Number of hosts? ___2^5-2=30 hosts per subnet._____________
(/28)
11111111.11111111.11111111.11110000
Dotted decimal subnet mask equivalent: ______255.255.255.240__________________________
Number of subnets? 2^4=16________________ Number of hosts? __2^4-2=14 hosts per subnet._______________
(/29)
11111111.11111111.11111111.11111000
Dotted decimal subnet mask equivalent: _____255.255.255.248___________________________
Number of subnets? __2^5=32______________ Number of hosts? ___2^3-2=6 hosts per subnet______________
(/30)
11111111.11111111.11111111.11111100
Dotted decimal subnet mask equivalent: _____255.255.255.252___________________________
Number of subnets? ___2^6=64_____________ Number of hosts? __2^2-2=2 hosts per subnet_______________
6)
Considering your answers, which
subnet masks meet the required number of minimum host addresses?
____/25 /26 /27 ____________________________________________________________________________
7)
Considering your answers, which
subnet masks meets the minimum number of subnets required?
___/27 /28 /29 /30
meet the required number of subnets _____________________________________________________________________________
8)
Considering your answers, which
subnet mask meets both the required minimum number of hosts and the minimum number
of subnets required?
_____/27.
It gives eight subnets. Greater than the minimum of six required, and 30 hosts
per subnet which is greater than the 25 hosts required for the first subnet.
9)
When you have determined which
subnet mask meets all of the stated network requirements, you will derive each
of the subnets starting from the original network address. List the subnets
from first to last below. Remember that the first subnet is 192.168.0.0 with
the newly acquired subnet mask.
Subnet Address / Prefix Subnet
Mask (dotted decimal)
____192.168.0.0_______ /
27 255.255.255.224 ____ _____
192.168.0.32___________/ _27___ ___255.255.255.224_______________________
_192.168.0.64_________ / _27___ _________255.255.255.224_________________
_192.168.0.96__________ / __27__ _255.255.255.224_________________________
192.168.0.128__________ / 27____ _____255.255.255.224_____________________
192.168.0.160______ / _27___ ____255.255.255.224______________________
192.168.0.192_____ / 27____ ___255.255.255.224_______________________
192.168.0.224__________ / 27____ ____255.255.255.224______________________
Step 2:
Complete the diagram showing
where the host IP addresses will be applied.
On the following lines provided, fill in
the IP addresses and subnets masks in slash prefix notation. On the router, use
the first usable address in each subnet for each of the interfaces, Gigabit
Ethernet 0/0, Gigabit Ethernet 0/1, loopback 0, and loopback 1. Fill in an IP
address for both PC-A and PC-B. Also enter this information into the Addressing
Table on Page 1.
Part 2:
Configure the Devices
In Part 2, set up the network topology
and configure basic settings on the PCs and router, such as the router Gigabit
Ethernet interface IP addresses, and the PC’s IP addresses, subnet masks, and
default gateways. Refer to the Addressing Table for device names and address
information.
Note: Appendix A provides configuration details for the steps in Part 2.
You should attempt to complete Part 2 prior to reviewing Appendix A.
Step 1:
Configure the router.
a.
Enter into privileged EXEC mode
and then global config mode.
b.
Assign the R1 as the hostname for the router.
c.
Configure both the G0/0 and G0/1 interfaces with IP addresses and subnet masks, and then enable
them.
d.
Loopback interfaces are created
to simulate additional LANs on R1 router. Configure the loopback interfaces
with IP addresses and subnet masks. After they are created, loopback interfaces
are enabled, by default. (To create the loopback addresses, enter the command interface loopback 0 at the global
config mode)
Note: You can create additional loopbacks for testing with different
addressing schemes, if desired.
e.
Save the running configuration
to the startup configuration file.
Step 2:
Configure the PC interfaces.
a.
Configure the IP address,
subnet mask, and default gateway settings on PC-A.
b.
Configure the IP address,
subnet mask, and default gateway settings on PC-B.
Part 3:
Test and Troubleshoot the
Network
In Part 3, you will use the ping command to test network
connectivity.
a.
Test to see if PC-A can
communicate with its default gateway. From PC-A, open a command prompt and ping
the IP address of the router Gigabit Ethernet 0/1 interface. Do you get a
reply? ___yes I got a
reply______________
b.
Test to see if PC-B can
communicate with its default gateway. From PC-B, open a command prompt and ping
the IP address of the router Gigabit Ethernet 0/0 interface. Do you get a
reply? ___yes, I got a
reply_____________
c.
Test to see if PC-A can
communicate with PC-B. From PC-A, open a command prompt and ping the IP address
of PC-B. Do you get a reply? __yes. I got a reply_______________
d.
If you answered “no” to any of
the preceding questions, then you should go back and check all of your IP
address and subnet mask configurations, and ensure that the default gateways
have been correctly configured on PC-A and PC-B.
e.
If you verify that all of the
settings are correct, and you can still not ping successfully, then there are a
few additional factors that can block ICMP pings. On PC-A and PC-B within
Windows, make sure that the Windows Firewall is turned off for the Work, Home,
and Public networks.
f.
Experiment by purposely
misconfiguring the gateway address on PC-A to 10.0.0.1. What happens when you
try and ping from PC-B to PC-A? Do you receive a reply?
_______no, you
won’t receive a reply _____________________________________________________________________________
____________________________________________________________________________________
Reflection
1.
Subnetting one larger network
into multiple smaller subnetworks allows for greater flexibility and security
in network design. However, what do you think some of the drawbacks are when
the subnets are limited to being the same size?
____Because some subnetworks require many IP addresses and
other requires only
afew. Having all of the subnets the same size is
not the most efficient way to divide the subnets.
________________________________________________________________________________
_______________________________________________________________________________________
2.
Why do you think the
gateway/router IP address is usually the first usable IP address in the
network?
__The router or the gateway is like the entrance to the
network. Therefore, it’slogical that
its address is
at the beginning
of the network.
It’s purely a convention,so the router doesn’t have the
1. or last address in the network
____________________________________________________________________________________
Router Interface Summary Table
|
Router Interface Summary
|
||||
|
Router Model
|
Ethernet Interface #1
|
Ethernet Interface #2
|
Serial Interface #1
|
Serial Interface #2
|
|
1800
|
Fast Ethernet 0/0 (F0/0)
|
Fast Ethernet 0/1 (F0/1)
|
Serial 0/0/0 (S0/0/0)
|
Serial 0/0/1 (S0/0/1)
|
|
1900
|
Gigabit Ethernet 0/0 (G0/0)
|
Gigabit Ethernet 0/1 (G0/1)
|
Serial 0/0/0 (S0/0/0)
|
Serial 0/0/1 (S0/0/1)
|
|
2801
|
Fast Ethernet 0/0 (F0/0)
|
Fast Ethernet 0/1 (F0/1)
|
Serial 0/1/0 (S0/1/0)
|
Serial 0/1/1 (S0/1/1)
|
|
2811
|
Fast Ethernet 0/0 (F0/0)
|
Fast Ethernet 0/1 (F0/1)
|
Serial 0/0/0 (S0/0/0)
|
Serial 0/0/1 (S0/0/1)
|
|
2900
|
Gigabit Ethernet 0/0 (G0/0)
|
Gigabit Ethernet 0/1 (G0/1)
|
Serial 0/0/0 (S0/0/0)
|
Serial 0/0/1 (S0/0/1)
|
|
Note: To find out how the router is configured, look at the interfaces
to identify the type of router and how many interfaces the router has. There
is no way to effectively list all the combinations of configurations for each
router class. This table includes identifiers for the possible combinations
of Ethernet and Serial interfaces in the device. The table does not include
any other type of interface, even though a specific router may contain one.
An example of this might be an ISDN BRI interface. The string in parenthesis
is the legal abbreviation that can be used in Cisco IOS commands to represent
the interface.
|
||||
Appendix A: Configuration Details for Steps in Part 2
Step 1:
Configure the router.
a.
Console into the router and
enable privileged EXEC mode.
Router> enable
Router#
b.
Enter into configuration mode.
Router# conf
t
Enter configuration commands, one per
line. End with CNTL/Z.
Router(config)#
c.
Assign a device name to the
router.
Router(config)# hostname R1
R1(config)#
d.
Configure both the G0/0 and G0/1 interfaces with IP addresses and subnet masks, and enable
them.
R1(config)# interface
g0/0
R1(config-if)# ip address <ip address> <subnet mask>
R1(config-if)# no shutdown
R1(config-if)# interface g0/1
R1(config-if)# ip address <ip address> <subnet mask>
R1(config-if)# no shutdown
e.
Loopback interfaces are created
to simulate additional LANs off of router R1. Configure the loopback interfaces
with IP addresses and subnet masks. When they are created, loopback interfaces
are enabled, by default.
R1(config)# interface
loopback 0
R1(config-if)# ip address <ip address> <subnet mask>
R1(config-if)# interface loopback 1
R1(config-if)# ip address <ip address> <subnet mask>
R1(config-if)# end
f.
Save the running configuration
to the startup configuration file.
R1# copy
running-config startup-config
Step 2:
Configure the PC interfaces.
a.
Configure the IP address,
subnet mask, and default gateway settings on PC-A.
b.
Configure the IP address,
subnet mask, and default gateway settings on PC-B.
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