So in summary when a device wants to communicate with a nother device in the same subnet it will send
a broadcast onto the local segment to find the MAC address of the device using the target IP address.
So in this case a sains the frame to the hub.
The hub because it's a multi port repeater will send the frame out of all ports except the port on which
it arrived.
So both the router and hoost see receive the frame Network Interface Cards will only accept unicast
traffic destined to their MAC address or they'll accept broadcast traffic as well as accepting multicast
traffic for multicast addresses that they subscribe to.
The router has a MAC address of g on interface first Ethan 00.
So the router will receive the broadcast and forward the request to Hialeah protocols the Rotto will
be able to see at least three that this is an odd request for IP address 10 1 1 2 but the Rodda in this
example is configured with IP addresses 10 1 one one hundred and 10 1 to 100.
So the ratable drop the frame because the request is not for one of its IP addresses.
Routers do not forward broadcasts.
So this broadcast is not forwarded out of interface Ethan it is 0 1 so the broadcast received by the
Rada is dropped.
The network interface card on PCC will receive the broadcast and see that this is an up request for
its IP address.
So it will then reply with an op reply.
As we've seen in the Why shall capture PCC will update its up cache to show that IP address 10 1 1 1
is associated with MAC address pay and it will then send the frame to the hub.
The Hubble forward the frame out of all ports because it's a multi-port repeater.
The route in this example will receive a frame from the hub but because the destination MAC address
is a and it's not the MAC address of the Rato which is g the rot it will drop the frame.
You will also receive a copy of the frame when it receives the frame it will accept it because the destination
address is a.
And its MAC address is a.
It will then update its up cache with an up entry stating that IP address 10 1 1 2 is associated with
MAC address C..
So the reply allows a to update its up cash.
At this point no user traffic has been transmitted.
What's happened here is that the devices have simply worked out which MAC addresses are associated with
which IP addresses.
So AA now knows that MAC address C is associated with IP address 10 1 1 2 the pink traffic cannot be
transmitted with a source of MAC address of a which is the local machine destination MAC address of
C..
In other words PCC the destination MAC address was learned through ARP source IP addresses change dog
wandered one to one destination IP address and that one would wonder too when the hub receives the frame
from PC it will repeat it out of all interfaces except the interface.
It arrived on.
So the router will once again receive the frame but will drop it because its MAC address is G and the
destination MAC address for this frame is c..
PCC will also receive the traffic and will accept it because the destination MAC address is C and its
local Mac addresses see the late two heads will be stripped and the IP address information will be read
by higher layer protocols.
This is an ICMP echo packet so the PC will reply with an echo reply message C will send the frame to
the hub with a source mac address of see destination MAC address of a EGNOS the MAC address of AA because
of the previous OP's request message.
So it's up cache has a in-tree associating MAC address a with IP address 10 1 1 1 source MAC address
and the frame is c..
Destination MAC address is a source IP address is 10 1 1 2 destination IP address is 10 1 1 1.
When the frame is received by the hub the Hubble repeated out of all ports except the one on which it
was received.
The Rotto will receive the frame but will drop it because the destination MAC address is not to G.
The local routers MAC address when it receives the frame from the hub it will accept it because the
destination MAC address is a and the PCs MAC addresses.
It will then strip layer 2 headers and forward the information to a higher layer protocols.
In this case it was an echo reply.
So the ping will show a success message.
In other words an echo request was sent to PCC and an echo reply message was successfully received back.
So in my wireshark capture for example I can filter on ICMP messages.
I can see the initial echo request a message sent from my PC to 10 0 0 0 2 4 4 and I can then see the
echo reply message.
Notice please that these are a unique cost frame's unicast.
Firstly from my PC to the local router and then a unicast from the router to my local machine the same
information would be displayed if you are pinging another local device on the segment as a user you
would see something similar to this.
Ping 10 0 0 2 4 4 and the ping was successful.
So in this example my PC successfully got a reply from the remote device that I was pinging.