Question about VLANS And router on the same environment?

suppose we have 3 switches that are connected to a router , and we have 3 VLans defined on each switch.


VLan1 connected Hosts are in the range 192.168.1.0/24


VLan2 connected Hosts are in the range 192.168.2.0/24


VLan3 connected Hosts are in the range 192.168.3.0/24





switch A --%26gt; Has VLan1,VLan2 and VLan3 .


switch B --%26gt; Has VLan1,VLan2 and VLan3 .


switch C --%26gt; Has VLan1,VLan2 and VLan3 .





suppose that a host that is connected to switch A through a port that is in VLan1 sent data to a host that is connected to switch C through a port that is in VLan2 . How will the router know on which interface he must forward the data to ?? each interface is connected to a switch that has VLAN2 ??


Does the router - in this situation - keeps the information in its routing table per host ??


I mean , for example :


192.168.2.1 via interface 1


192.168.2.2 via interface 2


192.168.2.3 via interface 3 and so on ..


or does it forward data on each interface??


Hope i cleared my Question


Thanks in advance

Question about VLANS And router on the same environment?
In order for a router to route packets from one vlan to a different vlan on the same interface, the router has to be trunked to the switch using a protocol such as 802.1q.


Using a Cisco router as an example, you would configure a sub-interface for each vlan, and assign an IP address for each sub-interface:





Interface FastEthernet 0/0


no ip address


Interface FastEthernet 0/0.1


IP address 192.168.1.1 255.255.255.0


encapsulation dot1q vlan 1


Interface FastEthernet 0/0.2


IP address 192.168.2.1 255.255.255.0


encapsulation dot1q vlan 2


Interface FastEthernet 0/0.3


IP address 192.168.3.1 255.255.255.0


encapsulation dot1q vlan 3





This is a scenario known as "Router on a stick."





Hope this helps.