1. Suppose the network implements a Link-state routing protocol between routers using a link cost factor related to the inverse of the link bandwidth (1/R) between each pair of routers. Apply Dijkstra algorithm to calculate the shortest paths from router R1 to each of the following destinations: Subnet1, Subnet 2, Subnet3 and the Internet.

 

2. Suppose the network uses all possible routes (and not just the shortest path) to forward traffic between a source and a destination. What is the maximum combined traffic flow from all three user subnets (Subnet1, Subnet2 and Subnet3) to the Internet if 100% link utilization is possible?

 

3. Suppose we set up a static route from R1 to R5 that goes through R1-R3-R5 (bypassing OSPF). Assume that the links R1-R3 and R3-R5 are each 200 Kilometers long and the speed of light in the medium is 2×10⁸ meters/second. R1 is sending 1000-bit messages to R5. Ignore processing and queuing delays. Suppose Stop-and-Wait flow control algorithm is implemented between routers; i.e. each router waits for an acknowledgment for its packet from the next router before sending the next packet. Calculate the overall throughput between R1 and R5.

Consider the following network with five routers (R1-R5) and three layer-2 switches (S1-S3). Router R5 is the main gateway that connects the network to the public Internet (shown as a cloud) using a 10Mbps link. The number next to each link indicates its data rate. The network includes three subnets (LANS) of PCs: Subnet 1, Subnet 2, and Subnet 3. Each subnet includes a number of PCs connected together with a layer-2 switch. Each PC has a 10 Mbps Ethernet connection. Note: The above applies to all the following parts (a, b, c) of this question. The question parts are independent of each other. Subnet 2 10 Mbps S1 10 Mbps Subnet 1 10 Mbps S2 R1 10 Mbps R3 4 Mbps 4 Mbps 1 Mbps 1 Mbps R2 2 Mbps R5 10 Mbps 4 Mbps R4 2 Mbps S3 Internet Subnet 3 Internet 10 Mbps