Stream of Knowledge

  In this lesson, we explain   what the OSI model is   in an easy and understandable language. It is one of the most important concepts in networking, so we break it down into pieces to help you understand exactly what its purpose is. What is data encapsulation? To understand the OSI model, you must first understand what data encapsulation is. Let's explore the following example. Imagine you want  to send a letter to a friend  who lives in another city to invite him to your wedding. What if you send the letter without an envelope, with any information, such as the sender's and recipient's names, addresses, and postcodes? What if you simply write the letter and drop it in the mailbox at the post office?  Most readers of this CCNA course are so young that  they've never sent a physical letter in their lives . They live in the digital age and have grown up with emails and instant text messages. However, surprisingly, everyone understands the concept of th...

protocols at each layer of OSI model The OSI (Open Systems Interconnection) reference model is a conceptual framework used to understand network interactions in seven distinct layers. Each layer has specific protocols that facilitate communication and data exchange. Let’s dive into the OSI model and explore the protocols that operate at each layer. Application layer It’s responsible for providing an interface for the user to interact with application services or network services. Ex- Web browser (HTTP), Telne Presentation layer It’s responsible for defining a standard format to the data. The major functions described at this layer are: - Encoding-Decoding Ex- AVI-(video), WAV-(voice), JPEG (graphite), ASCII (text) Encryption-Decryption Session layer It’s responsible for establishing, maintaining, and terminating the sessions. Session ID is used to identify a session or interaction. Ex- Remote procedural call, Apple talk session protocol. Transport Layer It provides data delivery me...

  Overview of OSPF Definition The Open Shortest Path First (OSPF) protocol, developed by the Internet Engineering Task Force (IETF), is a link-state Interior Gateway Protocol (IGP). At present, OSPF Version 2, defined in RFC 2328, is intended for IPv4, and OSPF Version 3, defined in RFC 2740, is intended for IPv6. Unless otherwise stated, OSPF stated in this document refers to OSPF Version 2. The following describes OSPF fundamentals, and basic OSPF function configuration. Understanding OSPF OSPF Fundamentals Router ID A router requires a router ID if it is to run OSPF. A router ID is a 32-bit unsigned integer, uniquely identifying a router in an AS. A router ID can be manually configured or automatically selected by a router: It is recommended that you manually configure a router ID to ensure OSPF stability. If no router ID is manually configured for a router, the router selects an interface IP address as its router ID. A router selects its router ID based on the following rules: ...