Cisco TCP/IP Routing Technology

Recently I started to read this book on TCP/IP routing technology. Although it is difficult to understand at the current level, I am still willing to go and see it. Every time you read a section, sort it out. Although not summarized in your own words. However, it is better to use some original articles. Because you have little experience. Understanding is not thorough enough. Extract the classic data. I will update it occasionally in the future. Please check. Please point out anything inappropriate. Thank you for your support!
 
Chapter 1
TCP/IP
1.1 TCP/IP protocol layer and OSI
 

Application Layer	Application Layer
Presentation Layer
Session Layer
Transport Layer	Host to host Layer
Network Layer	Internet Layer
Data Link Layer	Network Interface Layer
Physical Layer

 

Table of TCP/IP and OSI Layer 7 Models
The OSI reference model has become a legacy product of the history of the Internet. Currently, the OSI reference model is mainly used to learn networks. It is rarely used in practice. The dominant type is the TCP/IP protocol family.
Physical Layer: contains a variety of protocols related to physical media that support TCP/IP communication. There are four types of physical layer protocols:
Electronic/Optical protocols -------- describes various signal characteristics. For example, interface voltage, light intensity, encoding, and Signal Waveform
Mechanical agreement --------------- specifies the connector size and the metallic composition of the wire
Functional protocols ------------ describe what each physical medium does for example: EIA-232-D connector 4th pins feature: "Send request ".
Procedural Protocol ------------ describes how each physical medium is transferred, for example, binary 1 on a EIA-232-D wire represents a voltage <-3 V.
Data link layer:
The data link layer includes protocols for controlling the physical layer (MAC Sub-layer): describes how to access and share media, how to identify devices on media, and how to complete data frame before sending data on media. Typical data link layer protocols include IEEE 802.3, Ethernet, frame relay, and ATM.
At the same time, the data link layer also contains the protocol for controlling the Logical Link (LLC sub-layer), which describes the protocol for identifying the network layer and then encapsulating them. The LLC header tells the data link layer what data packets should be processed once a frame is received. The LLC sub-layer can also provide traffic control and control the sorting of bit streams. Protocol standard: IEEE 802.2
Network Layer:
The Internet layer corresponds to the OSI network layer. It is mainly responsible for defining the data packet format and address format and routing selection for data passing through the logical network path.
Transport Layer:
The OSI transport layer corresponds to the host-to-host layer, which specifies the protocol for controlling the Internet layer, just as the data link layer controls the physical layer, both the host-to-host layer and the data link layer define traffic control and error control mechanisms. They differ in that the data link layer emphasizes traffic control on the data link layer. That is, the traffic on the physical media connecting the two devices. The Transport Layer controls the traffic on the Logical Link. This logical connection may span a series of data links.
Application Layer, Session Layer, and presentation layer:
The application layer corresponds to the OSI application layer, Session Layer, and presentation layer. Some routing selection protocols use this layer. For example, Border Gateway Protocol (BGP) and Route Selection Information Protocol (RIP ). However, the most common service in the application layer is to provide network access interfaces to user applications.
BGP is an application layer protocol that uses TCP ports to send messages.
The RIP Protocol is also an application layer protocol, which uses UDP interfaces to transmit its messages.
OSPF is a network layer protocol that encapsulates messages in IP packets.
Multiplexing between layers is a common function for protocol families and other protocol families as shown above.
 
 
This article is from the "let Cisco fly" blog