Subnet 150.66.30.0/24 100 Mbps Ethernet R1 R2 1 Gbps Ethernet R3 Serial 1.544 Mbps 3. (9 points) Consider the 3-router network above. Assume that routers R1, R2 and R3 are running OSPF with default metric calculation and are synchronized. Fill in the table below with the OSPF metric (total path cost) to destination 150.66.30.0/24 for each router. OSPF Metric (Path Cost) Router Destination R1 150.66.30.0/24 R2 150.66.30.0/24 R3 150.66.30.0/24 4. (6 points) For PPP communications, explain why the CHAP protocol is more secure than the PAP protocol for user authentication. 5. (5 points) Frame Relay service was considered an upgrade from the previous X.25 packet services. What is an advantage of Frame Relay over X.25?