Layered network architecture breaks down complex communication systems into manageable parts. This approach offers modularity, simplification, and interoperability, allowing networks to adapt and grow. It's like building with LEGO blocks – each layer has a specific role, but they all work together seamlessly.
The layers work in harmony, with higher layers using services from lower ones. Think of it as a relay race, where each layer passes data to the next, adding its own "wrapper" of information. This structure helps manage the intricate process of sending data across networks efficiently and reliably.
Layered Network Architecture
Benefits of layered network architecture
- Modularity enables independent development and maintenance of each layer without affecting other layers
- Simplification of design and implementation by breaking down network communication into manageable parts focused on specific functions and responsibilities
- Interoperability through standardized interfaces between layers allows communication between devices from different manufacturers (Cisco, Juniper)
- Flexibility to easily integrate new protocols and technologies into the existing architecture (5G, Wi-Fi 6)
- Scalability allows the network to grow and adapt to increasing demands (more users, higher bandwidth)
Services between network layers
- Higher layer acts as the service user, while the lower layer acts as the service provider
- Service Access Points (SAPs) define the services provided by the lower layer to the upper layer through interfaces
- Upper layer uses services provided by the lower layer without concerning itself with implementation details
- Lower layer performs specific functions and abstracts complexity for the upper layer (error detection, flow control)
Roles of network architecture layers
- Application Layer provides network services to end-user applications
- HTTP for web browsing
- FTP for file transfer
- SMTP for email
- Transport Layer ensures reliable end-to-end data delivery between hosts
- Segments data and provides error detection and recovery
- TCP for reliable, connection-oriented communication
- UDP for faster, connectionless communication
- Network Layer responsible for routing packets between source and destination hosts across multiple networks
- Provides logical addressing (IP addresses) and path determination
- IP for addressing and routing
- ICMP for error reporting and diagnostics
- Data Link Layer facilitates reliable data transfer between adjacent network nodes
- Defines the format of data frames and provides error detection and correction
- Ethernet for wired LANs
- Wi-Fi for wireless LANs
- Physical Layer deals with the physical transmission of raw data bits over a communication medium
- Defines electrical, mechanical, and functional specifications for the physical connection
- Ethernet cables (Cat5, Cat6) for wired transmission
- Wireless channels (2.4 GHz, 5 GHz) for wireless transmission
Data encapsulation across network layers
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Encapsulation adds headers and trailers to the data at each layer before passing it to the next lower layer
- Each layer treats data received from the upper layer as the payload and adds its own header information
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Data flow across layers:
- Application Layer: Data
- Transport Layer: Segment = Data + Transport Header
- Network Layer: Packet = Segment + Network Header
- Data Link Layer: Frame = Packet + Data Link Header and Trailer
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Decapsulation removes corresponding headers as data moves up the layers at the receiving end
- Each layer removes its header and passes remaining data to the upper layer
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Data transmission across the network:
- Physical layer transmits raw data bits over the communication medium
- Data link layer ensures reliable delivery between adjacent nodes
- Network layer routes packets across multiple networks to reach the destination host
- Transport layer provides end-to-end reliability and data segmentation
- Application layer delivers data to the intended application