Протокол IP | Курс "Компьютерные сети"
Introduction to IP Protocol
Overview of IP Protocol
- The speaker introduces themselves as Andrey Sazykhin and presents the topic of the lecture: the Internet Protocol (IP).
- IP stands for "Internet Protocol," but it is more accurately translated as "inter-network protocol" or "protocol for inter-network interaction."
- The IP protocol predates the popularization of what we now refer to as the Internet, which is a network of networks.
Purpose and Functionality
- The primary goal of IP is to connect networks built on different data link layer technologies into a single large network.
- IP does not guarantee delivery or order of messages; it simply sends packets with the hope they reach their destination without acknowledgment if lost.
Key Features and Structure of IP
Network Integration
- One key task of IP is integrating diverse networks into one cohesive system where computers can communicate regardless of underlying technology.
Routing Mechanism
- Another critical function is routing, which involves finding paths from sender to receiver through intermediate routers.
Header Format
- The format of an IP packet header includes mandatory fields and optional fields, with two main versions currently in use: IPv4 and IPv6.
IPv4 Limitations and Transition to IPv6
Addressing Issues
- IPv4 has approximately 4.3 billion addresses, which are insufficient for all devices today; hence, IPv6 was proposed with a larger address space.
Header Fields Explained
- Key header fields include:
- Version: Indicates whether it's IPv4 or IPv6.
- Total Length: Specifies total packet size including header and data (max size 65535 bytes).
Fragmentation and Time-to-Live (TTL)
Fragmentation Process
- Fields like identifier, flags, and fragment offset are used for fragmentation management within packets.
Time-to-Live (TTL)
- TTL limits how long a packet can circulate in the network to prevent infinite loops caused by misconfigured routers. It decreases at each router hop.
Error Handling and Delivery Assurance
Error Detection Mechanism
- A checksum calculated only on the header ensures integrity; if errors are found during transmission, packets are discarded without notifying senders.
Addressing Information
- Sender's and receiver's addresses are included in the header; both are 32 bits long in IPv4.
Optional Fields in IP Headers
Options Usage
- Optional fields allow for additional functionalities such as route recording or timestamping through each router passed by a packet.
Routing Flexibility
- Options also enable manual routing configurations either through strict routes or flexible paths that may include alternative routers when necessary.