Question
Suppose now that the leftmost router in Figure 5.33 is replaced by a switch. Hosts A, B, C, and D and the right router are all star-connected into this switch. Give the source and destination MAC addresses in the frame encapsulating this IP datagram as the frame is transmitted (i) from A to the switch, (ii) from the switch to the right router, (iii) from the right router to F. Also give the source and destination IP addresses in the IP datagram encapsulated within the frame at each of these points in time.
Answer
To determine the source and destination MAC addresses in the frame encapsulating the IP datagram at different points in the network, we need to consider the network topology and the devices involved in"Figure 5.33 from the textbook".
In a star-connected network with a switch, the MAC addresses within the frame change at each hop as the frame moves from the source to the destination. Let's assume the following scenario:
Host A (Source) -> Switch -> Right Router -> Host F (Destination)
(i) Frame transmitted from A to the switch:
- Source MAC address: MAC address of Host A
- Destination MAC address: MAC address of the switch
Inside the frame, the encapsulated IP datagram will have:
- Source IP address: IP address of Host A
- Destination IP address: IP address of Host F
(ii) Frame transmitted from the switch to the right router:
- Source MAC address: MAC address of the switch
- Destination MAC address: MAC address of the right router
Inside the frame, the encapsulated IP datagram will have:
- Source IP address: IP address of Host A (remains unchanged)
- Destination IP address: IP address of Host F (remains unchanged)
(iii) Frame transmitted from the right router to Host F:
- Source MAC address: MAC address of the right router
- Destination MAC address: MAC address of Host F
Inside the frame, the encapsulated IP datagram will have:
- Source IP address: IP address of Host A (remains unchanged)
- Destination IP address: IP address of Host F (remains unchanged)
It's important to note that the specific MAC addresses and IP addresses will depend on the devices and their configurations in the network.