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Virtual LAN
Számítógép hálózatok gyakorlata
ÓBUDAI EGYETEM
2011 TAVASZI FÉLÉV
9. LABORGYAKORLAT
PRÉM DÁNIEL
Virtual Local Area Network
• VLAN ≠ WLAN
• Virtual LAN (logically related network)
broadcast domain inside the switch
• VLANs are stored in the VTP (VLAN trunking protocol)
databases
• Configurable parameters of VLANs:
name, type, state
• Some VLANs have a distinguished task, others can be
used as arbitrarily (e.g.: 1 = management vlan)
• Cisco VLAN ranges
– normal range: 1-1000 (configurable from 2)
– extended range: 1025-4096
Virtual Local Area Network
• Machines in the same VLAN see each other as
if they were in a normal LAN.
• Machines in separate VLANs don’t see traffic of
the other VLAN (not even when they are
connected to neighbouring ports on the same
switch – 2nd layer)
• Separate VLANs can only communicate if there
is routing between them (same as in normal
LANs) – 3rd layer
• VLANs need configurating on switches and
routers as well
VLAN Trunking
• Makes it possible to multiplex the traffic of
more than one logical networks on one
cable
• VLANID is used to separate the traffic
• Connection types:
– Access:
– Trunk:
1 VLAN traffic
Multiple VLANs batched
(dot1Q -> IEEE 802.1q standard)
VLAN configuration in routers
•
•
•
•
•
•
•
•
Router(config)# interface FastEthernet X/Y
Router(config-if)# no shutdown
Router(config-if)# exit
Router(config)# interface FastEthernet X/Y.Z
Router(config-subif)# encapsulation dot1Q [VLAN]
Router(config-subif)# ip address [IP addr.] [subnet mask]
Router(config-subif)# no shutdown
Router(config-subif)# exit
• Where:
– X,Y:
– Z:
– [VLAN]:
Interface ID
Sub interface ID (usually the VLANID)
The VLAN ID
VLAN configuration on Swiches
•
•
•
•
•
Switch> enable
Switch# configure terminal
Switch(config)# vlan [VLAN]
Switch(config-vlan)# name [VLAN_NAME]
Switch(config-vlan)# exit
• Where:
– [VLAN]:
is the VLAN ID
– [VLAN_NAME] is the friendly name of the VLAN
VLAN configuration on Swiches
• //one interface
Switch(config)# interface FastEthernet X/Y
• //interface range
Switch(config)# interface range FastEthernet X/Y-Z
• Switch(config-if-range)# switchport access vlan [VLAN]
• Switch(config-if-range)# no shutdown
• Switch(config-if-range)# exit
• Where:
– X,Y:
ID of the first interface
– Z:
ID of the last interface
– [VLAN]: The VLAN ID
VLAN configuration on Swiches
• //one interface
Switch(config)# interface FastEthernet X/Y
• // interface range
Switch(config)# interface range FastEthernet X/Y-Z
•
•
•
•
Switch(config-if-range)# switchport mode trunk
Switch(config-if-range)# switchport trunk allowed vlan add [VLAN 1]
Switch(config-if-range)# switchport trunk allowed vlan add [VLAN 2]
Switch(config-if-range)# switchport trunk allowed vlan add [VLAN N]
• Where:
– X,Y:
ID of the first interface
– Z:ID of the last interface
– [VLAN]:
The VLAN ID