2. CONTENTS
Introduction of LAN
Introduction of VLAN
Properties of VLAN
Types of VLAN
VLAN Identification methods
VLAN Trunking protocol
Inter-Vlan Routing
3. LAN
A Local Area Network (LAN) was originally defined as a network of computers
located within the same area.
Local Area Networks are defined as a single broadcast domain. This means that if
a user broadcasts information on his/her LAN, the broadcast will be received by
every other user on the LAN.
4. VLAN
A VLAN is a logical group of network devices that appears to be on the same
LAN.
Configured as if they are attached to the same physical connection even if they are
located on a number of different LAN segments.
Logically segment LAN into different broadcast domains.
VLAN’s can logically segment users into different subnets (Broadcast Domains)
Broadcast frames are only switched on the same VLAN ID.
This is a logical segmentation and not a physical one, workstations do not have to
be physically located together. Users on different floors of the same building, or
even in different buildings can now belong to the same LAN.
5. VLAN Range
By Default 5 VLAN’s created on a Switch, But only VLAN 1 belongs to
Ethernet network out of these 5 VLAN’s.
VLAN’s Usage
0 For System use only, You cannot see or use these VLAN.
1 Cisco default, We can use this VLAN but cannot delete it.
2-1001 Use for Ethernet VLAN’s, We can create, use and delete these VLAN’s
1002-1005 Cisco Default for FDDI and Token Ring. We can not delete these VLAN’s.
6. Properties of VLAN
Allows us to split switches into separate (virtual) switches.
To Reduce the cost of network.
Inter-VLAN traffic must be routed (i.e. go through a router) because they are separate
subnets
VLANs provide segmentation based on broadcast domains.
VLANs logically segment switched networks based on the functions, project teams, or
applications of the organization regardless of the physical location or connections to
the network.
All workstations and servers used by a particular workgroup share the same VLAN,
regardless of the physical connection or location.
7. VLANs address scalability, security, and network management.
Routers in VLAN topologies provide broadcast filtering, security,
and traffic flow management.
The switch behaves as several virtual switches, sending traffic only
within VLAN members.
8. Types of VLAN
A VLAN can be classified into two types:
Static Vlan
Dynamic Vlan
Static VLAN
Static Vlan are also referred to as port-based VLANs. In static VLAN
switch-ports must be manually assigned to a VLAN. Any device connecting
to that switch-port(s) becomes a member of that VLAN. The client device is
unaware that it belongs to a specific VLAN. Static VLAN is easy to
configure.
9. Dynamic VLAN
In dynamic VLAN devices are automatically assigned into a VLAN based on its MAC
address. This allows a client device to remain in the same VLAN, regardless of which
switch port the device is attached to. VLAN membership of a user always remains the
same even when he/she is moved to another location.
10. Types Of Port In VLAN
Access Ports: A port of switch which can carries the traffic of only one VLAN which
it belong to is known as Access Port.
Voice Access Ports: : Ports which can carry the voice data of other VLAN is known
as Voice Access Ports.
Trunk Ports: : A port which can carry the data of different VLAN.
11. Broadcast Domains With VLANs And Routers
Without VLANs
Without VLANs, each group is on a different IP network and on a
different switch.
12. With VLANs
Using VLANs. Switch is configured with the ports on the appropriate VLAN. Still, each
group on a different IP network; however, they are all on the same switch.
Sales
13. VLAN Identification Methods
Frame Tagging: VLAN Tagging, also known as Frame Tagging, is a method developed
by Cisco to help identify packets travelling through trunk links. When an Ethernet frame
traverses a trunk link, a special VLAN tag is added to the frame and sent across the
trunk link. There are two method of frame tagging which are given below.
Inter Switch Link: ISL is a cisco proprietary VLAN identification protocol used
on fast Ethernet ports. It can only use to trunk between cisco devices. ISL
actually re-encapsulate the entire original frame with a new header and new CRC
value.
IEEE 802.1q: It is an industry standard method of Vlan identification. This
protocol doesn’t entirely re-encapsulate a frame but instead of this it adds VLAN
identification information into frames.
14. VLAN Trunking protocol (VTP)
VLAN Trunk Protocol (VTP) reduces administration in a switched network. When
you configure a new VLAN on one VTP server, the VLAN is distributed through all
switches in the domain. This reduces the need to configure the same VLAN
everywhere. VTP is a Cisco-proprietary protocol.
15. VTP Server: In VTP server mode, you can create, modify, and delete VLANs and specify
other configuration parameters. VTP servers advertise their VLAN configuration to other
switches in the same VTP domain and synchronize their VLAN configuration with other
switches based on advertisements received over trunk links. VTP server is the default mode.
VTP Client: VTP clients behave the same way as VTP servers, but you cannot create,
change, or delete VLANs on a VTP client.
VTP Transparent: VTP transparent switches do not participate in VTP. A VTP transparent
switch does not advertise its VLAN configuration and does not synchronize its VLAN
configuration based on received advertisements, but transparent switches do forward VTP
advertisements that they receive out their trunk ports in VTP.
Modes Of VTP
16. Inter-Vlan Routing
Inter-Vlan routing allows the communication of two different VLAN
on a switch. To accomplish this we need a router or a layer 3 switch.
To support ISL and IEEE 802.1Q routing on a fast Ethernet interface
the router interface is divide into logical interface one for each Vlan,
these are called sub interface.
