VLAN- Virtual LAN:
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VLAN - Virtual LAN
• To segment layer 2 devices.
• VLAN provide layer 2 security.
• Divides a single broadcast domain into multiple broadcast domain and decrease the broadcast size,
• By default all ports of the switch are in VLAN1, This VLAN1 is known as administrative VLAN or management VLAN.
• VLAN can be created from 2 to 1001
• Can be configured on a a manageable switch only.
Types of VLAN:
• Static VLAN.
• Dynamic VLAN.
Static VLAN:
• Static VLANs are b ased on port numbers
• Need to manually assign a port on a switch to a VLAN
• Also calles port-based VLANs
• It can be a member of single VLAN and not multiples VLSNs
Dynamic VLAN:
• Dynamic VLANs are based on the MAC address of a PC
• Switch automatically assigns the port a VLAN.
• Each port can be a member of multiple VLANs
• For dynamic VLAN configurations a software called VMPS(VLAN Membership Policy Server) is needed.
Trunking:
Its is the process of enabling a VLAN between multiple switches.
Trunking should be enabled only in the fast Ethernet.
Trunk link:
It will forward or carry the VLAN information from one switch to another.
Access Link:
This link assigned to the accessing port from a VLAN.
Frame Tagging:
• It’s the process of adding a VLAM information along with a frame when its traveling through multiple switches.
• When the frame reaches the trunk port of the other switch that particular trunk port will drop the VLAN information and forward the frame to the correct destination.
• VLAN information must be stored in VLAN datatbase.
VLAN idendifications Method:
It is used to identify shich frame belongs to which VLAN.
There are 2 types:
1) ISL( Inter Switch Link)
2) IEEE802.1Q
ISL:
It’s a CISCO proprietary, We can trunk between only CISCO switches.
IEEE802.1Q:
IF you are trunking between CISCO switch and to a different brand of . Switch.
VLAN Configuration
The network lab has two Catalyst 2950T24 switches, with
names Maryland and California, and one Catalyst 2950G
Switch with name Virginia.
- The two Catalyst 2950T24’s in the network lab, each
has 24 10/100 Base T ports, and two 10/100/1000 Base T
ports i.e., gi0/1 and gi0/2.
- For Catalyst 2950G (i.e, Virginia), the two
10/100/1000 Base T ports are currently not installed
- The 24 10/100 Base T ports are: fa0/1, fa0/1,fa0/2, …
fa0/24
- Two 10/100/1000 Base T ports are: gi0/1 and gi0/2
. All the Cisco switches has two operational modes
- User Exec Mode :
When a user first establishes the connection with the
switch, and enter the password, the switch is in ‘User
EXEC Mode’, and the prompt is ‘>’.
- Privileged Mode: when user enter the command
‘enable’ and supply the password, it enters the
privileged mode, and the prompt is ‘#’
- Only in privileged mode, a user can enter configuration
mode; to enter configuration mode, user must enter the
command ‘config t’
. Configuration commands
- The following configuration commands explains how to
define a vlan name, assigning a static-access ports to a
VLAN, or deleting a VLAN.
- A VLAN port can be either in permanent trunk mode,
or in non-trunking mode as access
. What is a Trunk?
• A Trunk is a point-to-point link that transmit and receive
traffic between switches or switch and routers.
• Trunks carry the traffic of multiple VLANs and can
extend VLANs across an entire network
step command purpose
1 Config t Enter global configuration mode
2 Vlan vlan-id Enter a VLAN ID
3 Name vlan-name Enter a name for the VLAN
4 end Return to privileged mode
5 Show vlan {name id vlan-id } Verify your entries
6 copy running-cnofig startupconfig Save the configuration in the switch
Step Command Purpose
1 Config terminal Enter global configuration mode
2 Inter interface-id Enter the interface to be added to the
3 Switchport mode access Define the VLAN membership mode for the port
4 Switchport access vlan Vlan-id Assign the port to a VLAN
5 end Return to privileged EXEC mode
6 Show config or running-config Verify the VLAN membership of interf interface-id the interface
7 Sh interf interface-id switchport Verify your entries in the Administrativ mode access mode VLAN field
8 Copy running-config startupconfig Save your entires in the configuration Or wr mem
Catalyst 2950 T24 are:
• Interface fa0/i, where i= 1. 24 are the 24 10/100 Base T
ports
• Interface gi0/1 or 0/2 are the two 10/100/1000 Base T
ports
. The 24 ports of Catalyst 2950G Switch are:
• Interface fa0/i, where i= 1. 24
. Switchport mode access – interface is put into permanent
nontrunking mode
. Switchport mode trunk - interface into permanent
trunking mode
Examples of VLAN configuration
California#sh vtp status
/* show the vtp status */
California#sh vlan /*to show all the vlans configured */
California#config t /* this command cause the switch to enter configuration mode, when
all configuration is completed, enter either Ctrl^z or end to return to privileged
EXEC mode */
California(config)#vlan 10 name vlan10
/* defines name of vlan 10 as vlan10
California(config)#int fa0/1
California(config)#switchport mode access
California(config)#switchport access vlan 10 /* set port fa0/1
into vlan 10 */
California(config)#int fa0/2
California(config)#switchport mode access
California(config)#switchport access vlan 10
California(config)#int fa0/3
California(config)#switchport mode access
California(config)#switchport access vlan 10
/* at this point, vlan 10 has 3 members i.e., fa0/1, fa0/2 and fa0/3 */
California(config)#vlan 20 name vlan20
California(config)#int fa0/5
California(config)#switchport mode access
California(config)#switchport access vlan 20
California(config)#int fa0/6
California(config)#switchport mode access
California(config)#switchport access vlan 20
California(config)#int fa0/7
California(config)#switchport mode access
California(config)#switchport access vlan 20
Jan. 26,2010
7
VLAN
8
California(config)#int fa0/8
California(config)#switchport mode access
California(config)#ctrl-Z
California# /*return to privileged mode */
/* At this poing vlan 20 has 4 members i.e.,
fa0/5, fa0/6, fa0/7 and fa0/8 */
California(config)#int gi0/2
California(config)# switchport mode trunk
/* this will put the port gi0/2 to be in permanent
trunking mode */
California(config)#switchport access vlan 40
/* put int gi0/2 into vlan 40 */
California(config)#switchport access vlan 20
California(config)#end or ctrl-Z
/* return to privileged mode */
California#wr mem or copy running-config strtup-config
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