Virtual LAN

Számítógép hálózatok gyakorlata

Virtual Local Area Network

• • • • • • VLAN

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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: – Z: – ID of the first interface 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