(a) List the actions and routing decisions taken by all stations and routers to route an IP datagram containing an ICMP Echo Request transmitted by Station A to Station B.

(b) List the actions and routing decisions taken by all stations and routers to route an IP datagram containing an ICMP Echo Reply returned by Station B to Station A.

8. [15 marks] You are given the following internetworking scenario: Router 1 155.23.76.12 143.24.56.1 Token Ring 143.24.56.254 155.23.77.254 Ethernet Bridge Ethernet 155.23.77.253 Router 2 c 155.23.76.25 132.14.73.1 Token Ring 132.14.73.156 Ethernet The above IP network has just come on-line (i.e. all devices have just powered up). The routers contain the following decision tables: Router 1 Network Router Address Network Mask Interface Subnetwork c 132.14.0.0 155.23.76.253 255.255.0.0 143.24.56.0 local 255.255.0 a c 155.23.76.0 local 255.255.255.0 b 155.23.77.0 local 255.255.255.0 Router 2 Network Router Address Network Mask Interface Subnetwork c 143.24.0.0 155.23.77.254 255.255.0.0 b 155.23.76.0 local 255.255.255.0 local a 132.14.73.0 local 255.255.255.0 8. [15 marks] You are given the following internetworking scenario: Router 1 155.23.76.12 143.24.56.1 Token Ring 143.24.56.254 155.23.77.254 Ethernet Bridge Ethernet 155.23.77.253 Router 2 c 155.23.76.25 132.14.73.1 Token Ring 132.14.73.156 Ethernet The above IP network has just come on-line (i.e. all devices have just powered up). The routers contain the following decision tables: Router 1 Network Router Address Network Mask Interface Subnetwork c 132.14.0.0 155.23.76.253 255.255.0.0 143.24.56.0 local 255.255.0 a c 155.23.76.0 local 255.255.255.0 b 155.23.77.0 local 255.255.255.0 Router 2 Network Router Address Network Mask Interface Subnetwork c 143.24.0.0 155.23.77.254 255.255.0.0 b 155.23.76.0 local 255.255.255.0 local a 132.14.73.0 local 255.255.255.0