Interview Question about Network Packet Flow

Routing & Switching
1

During the interview from MNC, I was asked few question,
Regarding the difference of routers, switches and hubs,
and question of what is Vlan.
The last question I answered as below

Image 5-3-25 at 9.19 PM
Image 5-3-25 at 9.19 PM1072×568 124 KB

Can Anybody help answer what is packet flow for provided network diagram, I will provide the answer from the interview of MNC

3

Hello Rong

I assume that the packet flow you want described is for a communication between the PC and the Layer 3 switch at 3.3.3.2, correct?

  1. PC will create an IP packet with a source IP of 1.1.1.1 and a destination IP of 3.3.3.2. This will be encapsulated in a frame with a source MAC of MAC1 and a destination MAC of MAC 2 based on the default gateway. (ARP will be used to get the MAC of the default gateway if not already in the ARP table).
  2. Router will decapsulate, will examine the destination IP and determine the exit interface, and reencapsulate into another Ethernet Frame with MAC3 as the source, and MAC4 as the destination. ARP may be used to determine MAC4 based on the next hop IP in the routing table.
  3. Router will decapsulate, will examine the destination IP and determine the exit interface, and reencapsulate into another Ethernet Frame with MAC5 as the source, and MAC6 as the destination. ARP may be used to determine MAC6 based on the next hop IP in the routing table.

Does that make sense?

I hope this has been helpful!

Laz