OSI Model
The OSI model, which stands for Open Systems Interconnection model, is a conceptual framework used to understand and standardize how different networking protocols communicate over a network. Developed by the International Organization for Standardization (ISO) in 1984, the OSI model divides the complex process of network communication into seven distinct layers, each with its own set of functionalities and responsibilities.
Having a layered approach to networks, our hardware vendors would design hardware for the network, and others could develop software for the application layer. Using an open model which everyone agrees on means we can build networks that are compatible with each other.
The OSI model was developed in the hope that all present and future networking protocols would conform to its layers and operate within its framework. However, the TCP/IP model took precedence primarily due to its prevalent use on the Internet, and by the end of the 1990s, the vast majority of networking protocols adhered to the TCP/IP model rather than the OSI model.
However, the OSI model still remains today, primarily as a teaching tool to help students and learners understand the concepts involved in layered models in general. Today, very few protocols in networking strictly adhere to all the layers of the OSI mode. Most conform to the TCP/IP model.
Links
https://networklessons.com/cisco/ccna-200-301//introduction-to-the-osi-model
Links to this page:
- ARP Message Header and Payload
- Cisco Discovery Protocol (CDP)
- CoPP - Best practices and operation
- DHCP - Client ID
- DHCP - Message Types
- EIGRP - RTP's reliable message exchange process
- EIGRP - SIA Process and RTP retry attempts
- EIGRP - Static neighbors over any L2 technology
- Ethernet - speed and duplex mismatches
- Ethernet
- HSRP - Deployment in Distribution Layer
- Hardware - Layer-3-aware ASIC and IGMP snooping
- High-Level Data Link Control (HDLC)
- ICMP - Vulnerabilities
- IPSec - Encapsulating Security Payload (ESP)
- IPsec - does it support multicast
- IPv4 - header protocol field
- IS-IS
- Interface - no carrier counter
- Intrusion prevention system (IPS)
- Layer 2 network
- MAC Access List
- MPLS - Transport Profile
- MPLS - label
- MTU - Adjusting MTU to accommodate additional headers
- MTU - Benefits of large L2 MTU
- MTU - Interface MTU configuration considerations
- MTU - Interface MTU vs IP MTU
- Media Access Control (MAC)
- Multicast - PIM Snooping
- NAT - ports used for translation
- Network - BUM Traffic
- Network - Example of communication, encapsulation, and decapsulation, between hosts
- Network - Layer 3 network
- Network Design - Choosing a technology for multiple datacenter topology
- Network Design Achieving Redundancy with PE Devices
- Networks - Overlay Transport Virtualization (OTV)
- OSPF - A comparison with IS-IS
- OSPF IS-IS comparison
- PBR - matching prefix lists
- PTP - Precision Time Protocol
- Physical layer - Copper medium
- Physical layer - Wireless medium
- Physical layer - carrier wave
- Point-to-Point Protocol (PPP)
- Protocol Data Unit (PDU)
- QoS - CoS to DSCP and DSCP to CoS mapping
- QoS - Recommended router images for QoS labs in GNS3
- Routing - Dynamic routing protocols
- Routing - default gateway
- Routing
- STP - MST CST and CIST
- STP - Shortest Path Bridging (SPB)
- STP - UDLD and Fiber Links
- Switching - CEF Adjacency Table
- Switchport - show vlan internal usage
- Syslog
- TCP - factors affecting segment size
- TCP IP Model
- TCP header options
- Transport Layer port number
- UDP - Maximum Datagram Size
- VACL - use cases
- VLAN Tag
- VTP - protecting switches from lower revision numbers
- VXLAN - Use Cases
- Wireless - WLC authbypass feature