Cryptographic overhead of IPsec Protocol suit

Write a clear narrative on IPsec describing its function in details. State which are the cryptographic functions that are employed by the protocol during the packet exchange process. State which are the limitations of IPsec in relationship to the algorithm it uses. You need to critically present your arguments and scrutinise existing work on IPSec cryptographic overhead(s). Discuss the key attacks against IPSec and comment on its cryptographic resistance.
REPORT STRUCTURE
a. What is IPsec
b. IPsec main functions
c. IPsec cryptographic functions
d. Limitations and strength of IPsec
e. Main attacks to IPsec and its cryptographic resistance
f. Conclusions

REFRENCE
from 2011 to 2013 from IEEE and any guaranteed sources