Internetworking

4.4 Summary

Network architecture can have one of two types, one is defined by the OSI reference model and the other defined by the ARPANET model. The OSI reference model has seven protocol layers each of which builds upon the services offered by the subordinate layers to offer an enhanced service to the upper layers. The current Internet architecture was built on the ARPANET model which adopts four protocol layers. The main protocols used in the Internet architecture for network communication are TCP, UDP and IP protocols. IP protocol is a network layer protocol while TCP and UDP are transport layer protocols. The current IPv4 has a critical limitation, i.e., the limited address space so that it can not meet the demands of rapid growth of Internet. The study on the next generation of Internet protocol — IPv6 has been conducted for many years and will provide many new features as well as advantages compared with IPv4.