Osi-Model

Overview A MAC address is a hardware identifier burned into a network interface card and used to move frames across a single local link. An IP address is a logical network address assigned to a device and used to route packets across interconnected networks, including the internet. They operate at different OSI layers, working together to get data from one physical wire to a destination anywhere in the world. Comparison Diagram Host AIP 10.0.0.5Routerrewrites MAC per hopHost BIP 10.0.0.9MAC AA:01 to MAC RR:01MAC RR:02 to MAC BB:01Layer 2 - MAC changes at every hopIP 10.0.0.5 to 10.0.0.9Layer 3 - IP stays constant end-to-endMAC = local hop identity; IP = end-to-end address Comparison Table Aspect MAC Address IP Address OSI layer Layer 2 (Data Link) Layer 3 (Network) Format 48-bit hex, e.g. 00:1A:2B:3C:4D:5E 32-bit (IPv4) or 128-bit (IPv6) dotted/colon notation Assignment Burned in by the NIC manufacturer at production Assigned by a network admin or DHCP server Structure Flat, no hierarchy — vendor prefix plus serial Hierarchical — network portion plus host portion for routing Persistence Fixed to the physical interface (though spoofable) Can change when a device moves to a different network Role in delivery Identifies the next-hop device on the local link Identifies source and destination across the whole path Behavior across hops Rewritten by every router at each hop Preserved end-to-end (barring NAT) Resolution mechanism Discovered via ARP (IPv4) or NDP (IPv6) Discovered via DNS for hostnames Key Differences MAC address operates at Layer 2 while IP address operates at Layer 3. MAC is burned into hardware by the manufacturer, whereas IP is assigned by the network. A frame’s MAC addresses are rewritten at every hop, but the packet’s IP addresses stay end-to-end constant. ARP maps an IP address to the MAC address needed for delivery on the local segment. MAC addresses are flat with no structure, while IP addresses are hierarchical to support routing. When to Use Each MAC Address ...

Overview The OSI Model is a conceptual seven-layer framework that ISO designed to standardize how network communication should be described, while the TCP/IP Model is the four-layer protocol suite that actually powers the internet. Real devices implement TCP/IP directly, but engineers still borrow OSI’s vocabulary to reason about and troubleshoot problems layer by layer. Comparison Diagram OSI ModelTCP/IP Model7. Application6. Presentation5. Session4. Transport3. Network2. Data Link1. PhysicalApplicationTransportInternetNetwork Access Comparison Table Aspect OSI Model TCP/IP Model Purpose Theoretical reference model for describing how network communication should work Practical protocol suite that actually runs the internet Layer count 7 layers 4 layers (sometimes taught as 5) Layer structure Application, Presentation, Session, Transport, Network, Data Link, Physical Application, Transport, Internet, Network Access Development origin Designed by ISO in the late 1970s/80s before matching protocols existed Grew out of DARPA’s ARPANET; protocols came first, the model was described afterward Protocol coupling Layers defined independently of any specific protocol Layers map directly onto real protocols like IP, TCP, and HTTP Encapsulation granularity Splits presentation and session concerns into their own distinct layers Folds presentation and session functions into the single Application layer Real-world adoption Rarely implemented exactly as specified; used mainly as a teaching and reference framework Implemented in essentially every networked device and across the internet Troubleshooting use Provides layer-by-layer vocabulary for isolating where a problem occurs Maps directly to the tools and protocols engineers actually configure and debug Key Differences OSI has seven layers while TCP/IP condenses the same concerns into four layers OSI is a theoretical reference model; TCP/IP is the actual protocol suite running the internet OSI separates Session and Presentation into distinct layers; TCP/IP merges them into one Application layer TCP/IP’s protocols were built first and the model described them afterward, while OSI’s layers were designed before implementation When to Use Each OSI Model ...