Networking: Difference between Transport layer and Networking Layer

These are levels of abstraction. Transport Layer is where the decision to use TCP/UDP is made. Among commonly used protocols in this layer, TCP is reliable, UDP isn’t. Depending upon the choice made, the respective headers are attached to your packet. TCP for example just knows about SYN-ACK, Three-way handshake mechanisms, but does not know … Read more

In which layer is HTTP in the OSI model?

In which layer is HTTP in the OSI model? It’s in the application layer. See the following quotes from the RFC 7230, one of the documents that currently defines the HTTP/1.1 protocol: The Hypertext Transfer Protocol (HTTP) is a stateless application-level request/response protocol that uses extensible semantics and self-descriptive message payloads for flexible interaction with … Read more

Definition of Network Units: Fragment, Segment, Packet, Frame, Datagram

Taking from Section 1.2 in TCP/IP Illustrated: Vol 1 by Richard Stevens et al., consider the 4 layered TCP/IP stack: +————-+————————-+ | Application | Telnet, FTP, etc | +————-+————————-+ | Transport | TCP, UDP | +————-+————————-+ | Network | IP, ICMP | +————-+————————-+ | Link | drivers, interface card | +————-+————————-+ Segment: If the transport … Read more