Best path selected for IP packet

Routing & Switching OSPF
1

OSPF diagram
OSPF diagram1121×935 27.5 KB

please help to draw the packet flow of the network diagram
from the switch to both two routers.

thanks

2

Hello Rong

I assume this is the question about packet flow that you were asking about in this post?

In any case, I assume that the originating host is connected to the switch and is not the switch itself. Also I assume the destination is some host that is on the network that is connected to interface Ge1/1 on R1. Remember, defining the source and destination devices is important to determine packet flow.

  1. The packet enters a port on SW1 and the destination MAC is read. The destination MAC should be that of R3. The switch does a MAC address table lookup, determines the exit port, and sends it to R3.
  2. R3 receives it, decapsulates it to Layer 3, reads the destination IP, routes it, and determines that the exit interface should be Ge1/1. It is recapsulated, source and destination MACs are used from R3 and R2, respectively, and it is sent.
  3. R2 receives it, decapsulates it to Layer 3, reads the destination IP, routes it, and determines that the exit interface should be Ge0/1. It is recapsulated, source and destination MACs are used from R2 and R` respectively, and it is sent.
  4. R1 receives it, decapsulates it to Layer 3, reads the destination IP, routes it and determines that it is on the subnet connected to the Ge1/1 interface. It recapsulates it with the source MAC of R1 and the destination MAC of the destination host and sent out of Ge1/1.
  5. The frame is received by the destination host.

I hope this has been helpful!

Laz