Cisco Networking Academy Program
Youngstown State University
Cisco Regional Academy
Curriculum Review
Semester 3, v. 2.1.2
Chapter 3: Virtual LANs
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Disclaimer
This presentation is intended for review
purposes by Cisco Networking Academy Program
teachers and students only.
This presentation is not a substitute for careful
study of the Cisco Academy curriculum.
Most of the text and graphics have been copied
directly from the on-line curriculum, and remain
the copyrighted property of Cisco Systems.
CCNA 640-507 objectives are used for all YSU
Regional authored reviews.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Contents
Part 1: VLANs
Part 2: Segmenting with Switches
Part 3: VLAN Implementation
Part 4:Benefits of VLANs
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Chapter Learning Objectives
You will be able to:
– Define the role of a switch in creating VLANs.
– Describe frame filtering and frame tagging.
– Describe beneficial reasons for implementing
VLANs.
– Explain port centric, static, and dynamic
VLANs.
– Explain how VLANs control broadcasts.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Part 1
Virtual LANs
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
VLAN: Overview
 Traditional LANs are:
– Configured according to Layer 1
requirements.
– Grouped by their location
relative to the hub and cable
runs to the IDF/MDF.
– Not segmented by workgroup
association or need for
bandwidth.
– The “structure” is controlled by
the physical layout, not the
logical needs.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
VLANs: Overview
 A VLAN is a logical grouping of devices or
users that can be grouped by:
– function,
– department,
– or application,
 Regardless of their physical
segment location.
 Logical requirements rule
over the physical layout.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
VLANs: Overview
 A group of ports or users in the same
broadcast domain.
 Can be selected according to:
–
–
–
–
Port ID number
MAC address
Protocol
Application
 Use switches and
proprietary software.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Part 2
Segmenting with Switches
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Removing the Physical Boundary
 Using VLANs, you can group switch ports
and their users into logically defined
workgroups, such as:
– Coworkers in the
same department.
– A cross-functional
product team.
– User groups sharing the
same application.
 Single or multiple switches can be used.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
VLAN’s Across the Backbone
 To eliminate the physical restriction:
– VLAN information between interconnected switches
and routers, must be carried and reside on the
corporate backbone.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Routers in the VLAN
 Still provide:
– Broadcast control
– Route processing
– Subnet connectivity
 But now also:
– Connect the VLANs
that are “logically”
created but are not
on the same
“physical” location!
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
VLAN Frames
 Switches make filtering and forwarding
decisions by frame, using VLAN metrics.
– Frame filtering
– Frame tagging
 A frame is compared to
the metrics and then is:
– sent,
– filtered,
– or broadcast.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Frame Filtering
 Each switch develops a filtering table.
 Each frame can be filtered according to:
– MAC address, or
– Layer 3 protocol type
• IP
• IPX, etc.
 Like routers,
switches share
address table data
across the backbone.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Frame Tagging
 Places a unique ID in the header of each frame
as it is moves through the network backbone.
– ID is understood and examined by each switch prior
to any broadcasts or transmissions to other switches,
routers, or hosts.
– Functions at Layer 2; low administration!
– Selected by IEEE as
VLAN standard.
• IEEE 802.1q
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Part 3
VLAN Implementation
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
VLAN Ports and Broadcasts
 Each switch port can be assigned to a VLAN.
– Only ports assigned to the same VLAN share
broadcasts.
– Switched VLANs can therefore segment broadcast
domains like routers.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Types of VLANs
 Three types of VLAN implementation
– Port-centric
– Static
– Dynamic
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Port Centric
 All nodes connected to ports in the same
VLAN are assigned the same VLAN ID.
– Users are assigned by port.
– Easy administration.
– Increased security
between VLANs.
– Packets do not
"leak" into
other domains.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Static VLANs
 Switch ports are assigned to a VLAN.
– Any host that plugs into a port is automatically
a member of that port’s VLAN gorup.
 Easy to configure and monitor.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Dynamic VLAN’s
 Central database server maintains the VLAN
assignments.
– When a new host is connected to an open port, the
switch checks the database for VLAN assignment.
– Assignment
based on:
• MAC
• Logical address
• Protocol type.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Part 4
Benefits of VLANs
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Moving Hosts
 Physical moves are one of network managers
biggest headache.
– Moves and additions require the least amount of
reconfiguration when using VLANs.
– Hosts can move without
changing IP or subnet
membership as long as:
• They are connected to
a VLAN switch.
• Retain their VLAN ID.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
VLANs Control Broadcasts
 Switches not using VLANs, send broadcasts out
every port just like a hub.
 Broadcast traffic within one VLAN is not sent
outside that VLAN.
– The smaller the VLAN
membership, the less
hosts have to deal
with excess
broadcast traffic.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Improved Security
 A network manager can:
– Restrict the number of users in a VLAN group
– Prevent a user from joining the VLAN without first
receiving approval.
 Used with router ACL’s for tight control.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Save Money!
 Use existing hubs to connect many VLAN
members to the same VLAN switch port.
 Relocating a host to a new VLAN can be as
easy as plugging into a different hub.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
Summary
 Switched VLANs are a secure, layer 2, cost
effective way to group users regardless of
physical location.
 VLAN membership ID can travel the backbone.
 Common ID groupings are filtering, frame
tagging, and frame identification.
 VLAN’s provide
– Broadcast Control
– Workgroup security
– Cost effective additions or moving of hosts.
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor
Cisco Networking Academy Program
End
Robert E. Meyers CCNA, CCAI
Youngstown State University
Cisco Regional Academy Instructor