All language subtitles for 21. How is traffic routed between subnets

So in summary when the device wants to communicate

with another 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 sends 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 arrive.

So both the router and host C received the frame.

Network Interface Card will only accept unicast traffic destined
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to the Mac address or they�ll accept broadcast traffic
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as well as accepting multicast traffic
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for multicast addresses that they've subscribed to.
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The router has a MAC address of G on interface F0/0
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so the router will receive the broadcast
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and forward the ARP request to high layer protocols.
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The router will be able to see at layer 3 that this is an ARP request
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for IP address 10.1.1.2 but the router in this example is configured
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with IP addresses 10.1.1.100 and 10.1.2.100 so the router will drop
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the frame because the ARP request is not for one of one its IP addresses.
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Routers do not forward broadcast, so this broadcast is not forwarded
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out of interface F0/1.
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So the broadcast received by the router is dropped.
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The network interface card on PC C will received the broadcast
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and see that this is an ARP request forwards IP address.
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So it will then reply with an ARP reply
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as we�ve seen in the Wireshark capture.
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PC C will update its ARP cash to show that IP address 10.1.1.1 is
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associated with MAC address A and it will then send the frame to the hub
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The hub will forward the frame out of all ports
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because it�s a multiport repeater.
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The router in this example will receive a frame from the hub
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but because the destination MAC address is A
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and it�s not the MAC address of the router
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which is G the router will drop the frame.
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A will also receive a copy of the frame
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when A receives the frame it will accept it
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because the destination address is A and its MAC address is A.
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it will then update its ARP cache with and ARP entries
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stating that IP address 10.1.1.2 is associated with MAC address C.
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so the ARP reply allows A to update its ARP cache.
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At this point no user traffic has been transmitted
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what�s happen here is that the devices have simply worked out
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which MAC addresses are associated with which IP addresses.
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So A now knows that MAC address C is associated with IP address 10.1.1.2