Computer Networks CET2005B
Lab Assignments No 3
Title: Design Network: (Use: Packet Tracer/GNS)
Aim: Configure VLAN: (Use: Packet Tracer/GNS). Design and configure a
virtual LAN.
Objectives:
1. To learn and understand the concept of VLANs and their importance in
network design. To design a network using various network topologies in
Cisco Packet Tracer.
Theory: (Handwritten & Scanned)
1. What is VLAN ?
A VLAN (Virtual Local Area Network) is a subnetwork that groups
together a collection of devices from different physical LANs. VLANs
allow network administrators to partition a physical network into
multiple, distinct broadcast domains, effectively isolating network traffic
and improving security, efficiency, and management. By segmenting the
network, VLANs reduce congestion, enhance security by limiting access
to sensitive resources, and allow for the logical grouping of users and
devices based on function rather than physical location.
VLANs are particularly useful in large networks, where separating traffic
by department, function, or user type can optimize performance and
management. For example, a company might create separate VLANs for
the HR department, finance, and IT, ensuring that each department's data
traffic is isolated from the others, even though they share the same
physical network infrastructure.
2. Design Your VLAN Topology.
Consider a medium-sized company with three departments: HR, Finance,
and IT. Each department will have its own VLAN to separate network
traffic. Here’s a basic VLAN topology:
VLAN 10 - HR Department: IP Range 192.168.10.0/24
VLAN 20 - Finance Department: IP Range 192.168.20.0/24
VLAN 30 - IT Department: IP Range 192.168.30.0/24
VLAN Topology:
Switch A: Connects all devices from the HR department.
Switch B: Connects all devices from the Finance department.
Switch C: Connects all devices from the IT department.
Router: Connects to all switches and facilitates inter-VLAN routing.
Trunk Ports: Configure the ports between switches and the router as trunk
ports to carry traffic for all VLANs.
3. VLAN Configuration with switch configuration commands.
enable
configure terminal
vlan 10
name Sales
exit
vlan 20
name Marketing
exit
vlan 30
name IT
exit
vlan 99
name Management
exit
interface range fastethernet 0/1 - 8
switchport mode access
switchport access vlan 10
exit
interface range fastethernet 0/9 - 16
switchport mode access
switchport access vlan 20
exit
interface range fastethernet 0/17 - 22
switchport mode access
switchport access vlan 30
exit
interface range fastethernet 0/23 - 24
switchport mode access
switchport access vlan 99
exit
end
copy running-config startup-config
Design Screenshots:
Students Observation:
In conclusion, VLANs are a powerful tool for managing and optimizing
network resources by logically segmenting a physical network into multiple isolated
broadcast domains. This segmentation enhances network security, reduces traffic
congestion, and allows for easier management of network resources. By configuring
VLANs on switches and implementing inter-VLAN routing, organizations can
efficiently control and direct data flow between different departments or user groups
while maintaining the flexibility to scale the network as needed. Proper VLAN
implementation is essential for creating a secure, efficient, and well-organized
network infrastructure, especially in environments where multiple departments or
functions must coexist on the same physical network.
FAQ
How are VLANs Different from Physical LANs?
VLANs (Virtual Local Area Networks) differ from physical LANs in that they
allow for the segmentation of a single physical network into multiple logical
networks. While physical LANs are based on the actual hardware connections,
VLANs create separate networks that can operate independently within the
same physical infrastructure. This logical segmentation provides flexibility,
allowing administrators to group devices based on function, department, or
security needs rather than their physical location. VLANs also reduce broadcast
traffic, improve security by isolating sensitive data, and allow for more
efficient use of network resources.
Can Devices in Different VLANs Communicate with Each Other?
Devices in different VLANs cannot directly communicate with each other
without the help of a Layer 3 device, such as a router or a Layer 3 switch. This
separation is one of the main security features of VLANs, as it ensures that
traffic is isolated between different VLANs. To enable communication between
VLANs, inter-VLAN routing must be configured. This process involves
creating sub-interfaces on a router or using a Layer 3 switch to route traffic
between the VLANs, effectively bridging the communication gap while
maintaining network segmentation.
What is a VLAN Trunk?
A VLAN trunk is a network link that carries traffic for multiple VLANs across
network devices, such as switches or between a switch and a router. Trunk
ports are configured to tag frames with a VLAN identifier, using a protocol like
IEEE 802.1Q, so that devices on either end of the trunk can differentiate the
traffic and direct it to the appropriate VLAN. Trunks are essential for extending
VLANs across multiple switches or for connecting VLANs to routers for
inter-VLAN communication. By using a trunk, network administrators can
manage VLAN traffic efficiently and maintain VLAN separation across a
broader network infrastructure.
