Chapter 10 - Network Protocols Flashcards
Network Protocols
Network Protocols are the standards by which network messages are constructed.
The protocols themselves are complicated enough that layered models have been developed to describe them.
The two most common models are the OSI network model and the TCP/IP network model. These two models are described in detail in this section.
The OSI Network Model
Open System interconnect is a seven-layer model whose layers represent various abstractions of communication.
Each layer provides services to the layer above it and receives services from the layer beneath.
The common terminology for these layers is a protocol stack.
The layers of the OSI Model
- Physical
- Data Link
- Network
- Transport
- Session
- Presentation
- Application
Physical Layer
This is the lowest layer of the OSI model. It deals with the physical connection between devices. It defines the hardware elements involved, such as cables, switches, and network interface cards.
Functions: Bit transmission over a medium, defining voltage levels, data rates, physical connectors, etc
Data Link Layer
This layer is responsible for creating a reliable link between two directly connected nodes, managing errors in the physical layer, and controlling the flow of data.
Functions: Error detection and correction, frame synchronization, logical link control, and MAC addressing.
Network Layer
Determines the best path to route data packets from the source to the destination across the network.
Functions: Packet forwarding, routing, logical addressing (like IP addresses), and error handling and packet sequence control.
Transport Layer
Ensures the reliable arrival of messages and provides error-checking mechanisms and data flow controls.
Functions: Segmenting data and reassembling it into complete messages, ensuring data integrity, and establishing, maintaining, and terminating connections.
Session Layer
Manages sessions or connections between applications on different devices. It establishes, maintains, and terminates connections.
Functions: Dialog control (keeping data in sync), session establishment, maintenance, and termination.
Presentation Layer
Acts as a translator between the application and the lower layers. It converts the data format from one presentation to another (for example, EBCDIC to ASCII).
Functions: Data translation, encryption, compression, and interpretation of data between application and transport layers.
Application Layer
The topmost layer, it provides network services to end-users. It facilitates end-user processes and network services like email and file transfer.
Functions: End-user interface, email, file transfer, remote login, and management services.
TCP/IP
The TCP/IP network protocol is built on a four-layer model:
- Link
- Internet
- Transport
- Application
TCP/IP Link Layer
The link layer is layer 1 in the TCP/IP model. The link layer is concerned with node-to-node delivery of bits or frames. Examples of link layer technologies include:
- WiFi
- Ethernet
- Token ring
TCP/IP Internet Layer
The Internet layer is layer 2 in the four-layer TCP/IP model.
The Internet layer is the layer that is concerned with end-to-end packet delivery, whereas layer 1 is concerned with node-to-node delivery. End-to-end delivery means that a packet can originate at one node and pass through several intermediate nodes (usually routers) before arriving at the destination node
Internet Layer Protocols
- Internet Protocol Version 4 (IPv4)
- Internet Protocol version 6 (IPv6)
- Address Resolution Protocol (ARP)
- Reverse Address Resolution Protocol (RARP)
- Internet Control Message Protocol (ICMP)
- Internet Group Management Protocol (IGMP)
- IP security (IPsec)
Internet Layer Routing Protocols
Routing protocols are used by network routers to determine how to send network packets to nodes on destination networks. Some network routing protocols exist in the Internet layer, including:
- RIP
- OSPF
- IS-IS
- BGP
