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Embed code for: 02.4 TCP IP Reference Model
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02.4 TCP IP Reference Model
9/11/2016 Cisco ELearning for ICND1 v2.0 https://ondemandelearning.cisco.com/ciscosc/icnd1#/sections/2/pages/4 1/2 TCP/IP Reference Model Section 2: Understanding the HosttoHost Communications Model TCP/IP is actually two protocols, but they are used together so often that many people think of it as a single protocol. TCP operates at Layer 4 and is responsible for making sure that data that is sent arrives at its destination. IP operates at Layer 3 and is responsible for transmission of data. It does not do any error correction itself. The TCP/IP reference model is similar to the OSI model and also separates data communication into layers. It predates the OSI model and consists of only four layers. The TCP/IP model provides a common reference for maintaining consistency within all types of network protocols and services. It is not intended to be an implementation specification or to provide sufficient detail to precisely define the services of the network architecture. The primary purpose of this reference model is to aid in understanding the functions and processes that are involved in data communication. Although this course refers to the TCP/IP stack, it has become common in the industry to shorten this term to "IP stack." Take a look at the four layers of the TCP/IP model. Layer 1 is the network access layer: This layer is the equivalent of both the physical and data link layers of the OSI model. It deals with components such as cables, connectors, and network cards, like OSI Layer 1. Like Layer 2 of the OSI model, the network access layer of the TCP/IP model is concerned with hardware addresses. Layer 2 is the Internet layer and aligns directly with Layer 3 of the OSI model: It routes data from the source to the destination by defining the packet and the addressing scheme, moving data between the network access and transport layers, routing packets of data to remote hosts, and performing fragmentation and reassembly of data packets. This is the layer where IP operates. Layer 3 is the transport layer and is directly aligned with Layer 4 of the OSI model: This layer is the core of the TCP/IP architecture. It is the layer where TCP and UDP operate. This layer provides communication services directly to the application processes that are running on network hosts. 9/11/2016 Cisco ELearning for ICND1 v2.0 https://ondemandelearning.cisco.com/ciscosc/icnd1#/sections/2/pages/4 2/2 Layer 4 is the application layer and corresponds to Layers 5, 6, and 7 of the OSI model: It provides applications for file transfer, network troubleshooting, and Internet activities. It also supports network APIs, which allow programs that have been created for a particular operating system to access the network. Up Next: OSI Model vs. TCP/IP Stack