Topology
Objectives
Part 1: Examine the Network
Requirements
Part 2: Design the VLSM Address
Scheme
Part 3: Cable and Configure the IPv4
Network
Background / Scenario
The Variable Length Subnet Mask (VLSM)
was designed to help conserve IP addresses. With VLSM, a network is subnetted
and then subnetted again. This process can be repeated multiple times to create
subnets of various sizes based on the number of hosts required in each subnet. Effective
use of VLSM requires address planning.
In this lab, you are given the network
address 172.16.128.0/17 to develop an address scheme for the network shown in
the Topology diagram. VLSM will be used so that the addressing requirements can
be met. After you have designed the VLSM address scheme, you will configure the
interfaces on the routers with the appropriate IP address information.
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). Other routers 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 the end of this lab for the correct interface identifiers.
Note: Make sure that the routers have been erased and have no startup
configurations. If you are unsure, contact your instructor.
Required Resources
·
3 Routers (Cisco 1941 with
Cisco IOS Release 15.2(4)M3 universal image or comparable)
·
1 PC (with terminal emulation program,
such as Tera Term, to configure routers)
·
Console cable to configure the
Cisco IOS devices via the console ports
·
Ethernet (optional) and serial
cables as shown in the topology
·
Windows Calculator (optional)
Part 1:
Examine the Network
Requirements
In Part 1, you will examine the network
requirements to develop a VLSM address scheme for the network shown in the
Topology diagram using the network address of 172.16.128.0/17.
Note: You may use the Windows Calculator application and the www.ipcalc.org
IP subnet calculator to help with your calculations.
Step 1:
Determine how many host
addresses are available and how many subnets are needed.
How many host addresses are available in
a /17 network? ________
What is the total number of host
addresses needed in the topology diagram? ________
How many subnets are needed in the
network topology? ______
Step 2:
Determine the largest subnet
needed.
Subnet description (e.g. BR1 G0/1 LAN or
BR1-HQ WAN link) ___________________
How many IP addresses are needed in the
largest subnet? __________
What is the smallest subnet that supports
that many addresses?
_____________________
How many host addresses does that subnet support?
_________
Can the 172.16.128.0/17 network be
subnetted to support this subnet? _____
What are the two network addresses that would
result from this subnetting?
_____________________
_____________________
Use the first network address for this
subnet.
Step 3:
Determine the second largest
subnet needed.
Subnet description
_____________________________
How many IP addresses are needed for the
second largest subnet? ______
What is the smallest subnet that supports
that many hosts?
___________________
How many host addresses does that subnet support?
__________
Can the remaining subnet be subnetted
again and still support this subnet? ______
What are the two network addresses that
would result from this subnetting?
_____________________
_____________________
Use the first network address for this
subnet.
Step 4:
Determine the next largest
subnet needed.
Subnet description
_____________________________
How many IP addresses are needed for the next
largest subnet? ______
What is the smallest subnet that supports
that many hosts?
___________________
How many host addresses does that subnet
support? __________
Can the remaining subnet be subnetted
again and still support this subnet? ______
What are the two network addresses that
would result from this subnetting?
_____________________
_____________________
Use the first network address for this
subnet.
Step 5:
Determine the next largest
subnet needed.
Subnet description _____________________________
How many IP addresses are needed for the
next largest subnet? ______
What is the smallest subnet that supports
that many hosts?
___________________
How many host addresses does that subnet
support? __________
Can the remaining subnet be subnetted
again and still support this subnet? ______
What are the two network addresses that
would result from this subnetting?
_____________________
_____________________
Use the first network address for this
subnet.
Step 6:
Determine the next largest
subnet needed.
Subnet description
_____________________________
How many IP addresses are needed for the
next largest subnet? ______
What is the smallest subnet that supports
that many hosts?
___________________
How many host addresses does that subnet
support? __________
Can the remaining subnet be subnetted
again and still support this subnet? ______
What are the two network addresses that
would result from this subnetting?
_____________________
_____________________
Use the first network address for this
subnet.
Step 7:
Determine the next largest
subnet needed.
Subnet description
_____________________________
How many IP addresses are needed for the
next largest subnet? ______
What is the smallest subnet that supports
that many hosts?
___________________
How many host addresses does that subnet
support? __________
Can the remaining subnet be subnetted
again and still support this subnet? ______
What are the two network addresses that
would result from this subnetting?
_____________________
_____________________
Use the first network address for this
subnet.
Step 8:
Determine the subnets needed to
support the serial links.
How many host addresses are needed for
each serial subnet link? ______
What is the smallest subnet that supports
that many host addresses?
___________________
a.
Subnet the remaining subnet and
write the network addresses that result from this subnetting below.
___________________
___________________
b.
Continue subnetting the first
subnet of each new subnet until you have four /30 subnets. Write the first three
network addresses of these /30 subnets below.
___________________
___________________
___________________
c.
Enter the subnet descriptions
for these three subnets below.
____________________________
____________________________
____________________________
Design the VLSM Address Scheme
Step 9:
Calculate the subnet
information.
Use the information that you obtained in
Part 1 to fill in the table below.
|
Subnet Description
|
Number of Hosts Needed
|
Network Address /CIDR
|
First Host Address
|
Broadcast Address
|
|
HQ G0/0
|
16,000
|
172.16.128.0/18
|
172.16.128.1
|
172.16.191.255
|
|
HQ G0/1
|
8,000
|
172.16.192.0/19
|
172.16.192.1
|
172.16.223.255
|
|
BR1 G0/1
|
4,000
|
172.16.224.0/20
|
172.16.224.1
|
172.16.239.255
|
|
BR1 G0/0
|
2,000
|
172.16.240.0/21
|
172.16.240.1
|
172.16.247.255
|
|
BR2 G0/1
|
1,000
|
172.16.248.0/22
|
172.16.248.1
|
172.16.251.255
|
|
BR2 G0/0
|
500
|
172.16.252.0/23
|
172.16.252.1
|
172.16.253.255
|
|
HQ S0/0/0 – BR1 S0/0/0
|
2
|
172.16.254.0/30
|
172.16.254.1
|
172.16.254.3
|
|
HQ S0/0/1 – BR2 S0/0/1
|
2
|
172.16.254.4/30
|
172.16.254.5
|
172.16.254.7
|
|
BR1 S0/0/1 – BR2 S0/0/0
|
2
|
172.16.254.8/30
|
172.16.254.9
|
172.168.254.11
|
Step 10:
Complete the device interface address
table.
Assign the first host address in the
subnet to the Ethernet interfaces. HQ should be given the first host address on
the serial links to BR1 and BR2. BR1 should be given the first host address for
the serial link to BR2.
|
Device
|
Interface
|
IP Address
|
Subnet Mask
|
Device Interface
|
|
HQ
|
G0/0
|
|
|
16,000 Host LAN
|
|
G0/1
|
|
|
8,000 Host LAN
|
|
|
S0/0/0
|
|
|
BR1 S0/0/0
|
|
|
S0/0/1
|
|
|
BR2 S0/0/1
|
|
|
BR1
|
G0/0
|
|
|
2,000 Host LAN
|
|
G0/1
|
|
|
4,000 Host LAN
|
|
|
S0/0/0
|
|
|
HQ S0/0/0
|
|
|
S0/0/1
|
|
|
BR2 S0/0/0
|
|
|
BR2
|
G0/0
|
|
|
500 Host LAN
|
|
G0/1
|
|
|
1,000 Host LAN
|
|
|
S0/0/0
|
|
|
BR1 S0/0/1
|
|
|
S0/0/1
|
|
|
HQ S0/0/1
|
Part 2:
Cable and Configure the IPv4
Network
In Part 3, you will cable the network
topology and configure the three routers using the VLSM address scheme that you
developed in Part 2.
Step 1:
Cable the network as shown in
the topology.
Step 2:
Configure basic settings on
each router.
a.
Assign the device name to the
router.
b.
Disable DNS lookup to prevent
the router from attempting to translate incorrectly entered commands as though
they were hostnames.
c.
Assign class as the privileged EXEC encrypted password.
d.
Assign cisco as the console password and enable login.
e.
Assign cisco as the vty password and enable login.
f.
Encrypt the clear text
passwords.
g.
Create a banner that warns
anyone accessing the device that unauthorized access is prohibited.
Step 3:
Configure the interfaces on
each router.
a.
Assign an IP address and subnet
mask to each interface using the table that you completed in Part 2.
b.
Configure an interface
description for each interface.
c.
Set the clocking rate on all
DCE serial interfaces to 128000.
HQ(config-if)# clock rate 128000
d.
Activate the interfaces.
Step 4:
Save the configuration on all
devices.
Step 5:
Test Connectivity.
a.
From HQ, ping BR1’s S0/0/0 interface
address.
b.
From HQ, ping BR2’s S0/0/1
interface address.
c.
From BR1, ping BR2’s S0/0/0
interface address.
d.
Troubleshoot connectivity
issues if pings were not successful.
Reflection
Can you think of a shortcut for calculating
the network addresses of consecutive /30 subnets?
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
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.
|
||||
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