As shown in the following figure, two IPv6 networks use two gateway routers, GA and GB, respectively, to connect to an IPv4 networks. GA and GB use IPv6-in-IPv4 Tunneling mechanism to deliver IP datagrams between two IPv6 networks across IPv4 networks. Suppose that host A sends an IPv6 datagram to host B.|(1%+3%+1%+3%+3%+3%) A Ri GA R2 R3 GB R4 B IPv6 - IPv6 IPv6/v4: IPv4 IPv4 IPv4/v6 IPv6 IPv6 (a) What is the protocol that A, R1 and GA use to deliver the above datagram to GA? (b) Show the source, destination and type of addresses in the datagram sent by A. (c) What is the protocol that GA, R2 and R3 use to deliver the datagram to GB? (d) How does GA do when it receives the datagram, destined for B, sent by A? ( You also need to mention what source & destination changes.) (e) What is the payload of the datagrams that GA sends to GB? (f) How does GB do when it receives the datagram from R3? ( You also need to mention what source & destination changes. )