So welcome back, guys.
In this module we will going to learn router Vlan routing.
That is how l3 router can deliver a traffic that is destined to some host machine say machine A which
is present in one of the villains.
In this example it is Vlan 12.
So essentially we will going to discuss that how a host machine present in a Vlan and a gateway l3 router
can actually communicate with each other.
In the previous module we discussed that how host machines present in the same Vlan can exchange or
communicate with each other using L2 switch and using the concept of Vlan tagging.
In this module, we will learn how communication between Gateway L3 router and a host machine present
in one of the VLANs can take place.
So, guys, going forward.
So remember, villains are nothing, but they are subnets.
So just stick to the basics that villains are subnets.
That is a group of machines present in the same Vlan can communicate with each other using L2 routing.
So in this module we shall understand that how an L3 router delivers a traffic which is received from
outside to the host machine present in one of the local VLANs.
So in this case you can see in this diagram, suppose this L3 router receives a traffic which is destined
for 13 .1.1.4.
Now here the destination IP address present in the IP header of the packet is 13 .1.1.4.
And remember a traffic which is actually being routed on the L3 network is always an untagged packet.
It do not have any 802.1 q header only when a traffic travels in a Vlan subnet then only it is tagged
with 802.1 q header.
So always remember a traffic which is flowing over l3 network is always untagged.
So now when this L3 router receives this traffic on one of the local interface, how this L3 router
will going to deliver this traffic to the host machine for which this traffic is destined.
You can see the destination IP address of the traffic matches with the IP address assigned to the host
machine A and this host machine A is present in Vlan 12.
So the l3 Router's job is to deliver this traffic to the correct host machine which could be present
in any Vlan right.
All L3 router knows is the destination IP address of the host machine to which it has to deliver the
traffic.
So in this module we will going to learn that what is the mechanism used by L3 router to actually deliver
the traffic to the host machine present in a Vlan?