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1)VLAN on central switch.
en
conf t
hostname central_switch
no ip domain-lookup
vlan 10
name vlan10
exit

vlan 20
name  vlan20
exit

vlan 30 
name vlan30
exit

2) VLAN FOR PC1 on central_switch
interface fa0/1
description PC0
switchport mode access
switchport access vlan 10
no shutdown
exit

interface fa0/2
description PC1
switchport mode access
switchport access vlan 20
no shutdown
exit

interface fa0/7
description PC2
switchport mode access
switchport access vlan 30
no shutdown
exit


3) Trunk switch 1 from central_switch
interface fa0/4
description trunk_switch1
switchport mode trunk
switchport trunk allowed vlan 10,20,30
no shutdown
exit

4) Trunk switch 2 from central_switch
interface fa0/6
description trunk_switch2
switchport mode trunk
switchport trunk allowed vlan 10,20,30
no shutdown
exit

5) On switch1 trunk central and switch 2
en
conf t
hostname switch1
no ip dommain-lookup

vlan 10
name vlan10
exit

vlan 20
name  vlan20
exit

vlan 30 
name vlan30
exit

interface range fa0/2-3
description trunk_both_switch
switchport mode trunk
switchport trunk allowed vlan 10,20,30
no shutdown
exit


6) On switch2 trunk central and switch1
conf t
hostname switch2
no ip dommain-lookup

vlan 10
name vlan10
exit

vlan 20
name  vlan20
exit

vlan 30 
name vlan30
exit

interface range fa0/1-5
description trunk_both_switch
switchport mode trunk
switchport trunk allowed vlan 10,20,30
no shutdown
exit

7) configuring Router
hosthname router0
no ip domain-lookup
interface fa0/0
description link_to_switch
no shutdown

interface fa0/0.10
encapsulation dot1Q 10
ip address 167.167.20.1. 255.255.255.0
exit

interface fa0/0.20
encapsulation dot1Q 20
ip address 167.167.10.1. 255.255.255.0
exit

interface fa0/0.30
encapsulation dot1Q 30
ip address 167.167.30.1. 255.255.255.0
exit

on central switch check
show vlan brief

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