1. IPsec has been designed to be backward compatible with IPv4 and IPv6. In particular, in order to reap the benefits of IPsec, we don’t need to replace the protocol stacks in all the routers and...

1. IPsec has been designed to be backward compatible with IPv4 and IPv6. In particular, in order to reap the benefits of IPsec, we don’t need to replace the protocol stacks in all the routers and hosts in the Internet. For example, using the transport mode (one of two IPsec “modes”), if two hosts want to securely communicate, IPsec needs to be available only in those two hosts. Discuss the services provided by an IPsec session.