Router R1 sits at an Enterprise branch office, using the Internet for its only connectivit

Router R1 sits at an Enterprise branch office, using the Internet for its only connectivity back to the rest of the EnterprisE.Which of the following is not a ben efit of using an IPsec tunnel for packets sent through the Internet, between R1 and the rest of the Enterprise?（）

A. Privacy

B. Authentication

C. Allows using an IGP between R1 and the Enterprise

D. Secure communications

参考C