IP header:Fragmentation

wlkankota

A router R1 acts as a gateway to a VPN tunnel. At the other end of the tunnel is another gateway R2. The two routers R1 and R2 are not directly connected to each other. Suppose that the Router R1 receives an IP datagram that needs to traverse the VPN tunnel. This implies that this incoming datagram needs to be encapsulated in another IP datagram before it can be sent over the VPN tunnel. However, R1’s path MTU information indicates that this incoming datagram also requires fragmentation. Now, router R1 has two options to deal with this situation:
Option 1: Encapsulate the original datagram and then subject the encapsulated packet to fragmentation.
Option 2: Fragment the original datagram and then encapsulate each resulting fragment.
Which of the two options should the router R1 opt for and why?

wlkankota

Also please explain why ..