Cisco CCNA Service Provider Question of the Week By Johnny Bass August 2, 2013 At what layer does IP protocol run in the legacy TCP/IP model? Transport Network Internet Session Application The correct answer is 3. The older TCP/IP model has 4 layers, network access, internet, transport and application. Internet layer is equivalent to the OSI model network layer. Related Courses: SPNGN1 – Building Cisco Service Provider Next-Generation Networks, Part 1 SPNGN2 – Building Cisco Service Provider Next-Generation Networks, Part 2 In this article CCNACertificationCiscoccna exam prepCertificationCisco Join the Conversation Cancel Reply Will not be published. Website 2 comments Mike Gibson 5 years ago Reply The correct answer is not internet it is Network. The reason is because the TCP/IP model has changed. Application Transport Network DataLink Physical In which Application matches to Application,Presentation,and Session of the OSI model. Johnny Bass 5 years ago Reply That is true, but the question asks about the “legacy TCP/IP model”, which is referred to as Internet, not network. Within the CCNA SP (and CCNA R&S) there is a contrast of the legacy versus the OSI model, which redefines the layers. The OSI model redefines layer 3 to be Network.