Lecture 2 Flashcards
Explain the different internet components and services
Internet is a computer network that interconnects billions of computing devices(hosts or end systems) worldwide
End systems are connected together by a network of communication links and packet switches(routers, switches)
Different types of communication links(coaxial cable, copper wire, optical fibre, radio, satellite) different data transmission rate bandwidth measured in bits/seconds
End systems send/receive packets(data + header bytes)
What is a route or path?
Sequence of communication links between end system is known as route or path.
How does the end system acces the internet?
End systems access the internet through Internet Service Providers (ISPs)
End systems, routers, switches run Protocols(TCP, IP, HTTP, SMTP, 802.11)
What are Requests for comments (RFCs)?
To ensure interoperability protocols adhere to Interenet standards developed by the Internet Engineering Task Force (IETF). These documents are called Request for comments
Explain more about the internet and its services
Internet is also an infrastructure that provides services to applications(distributed applications)
End systems provide programming interface to applications(socket interface)
What is a protocol
A protocol is a set of rules that defines the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or the receipt of a message or other event
Protocols for TCP/IP stack?
Application: supporting network applications (FTP, SMTP, HTTP)
Transport: process-process data (TCP, UDP)
Network: routing of data grams from source to destination (IP, routing protocols)
Link: data transfer between neighbouring network elements (Ethernet, 802.11 (WiFi), PPP)
Pyhsical: bits “ on the wire
Protocols for OSI stack?
SAME ONES AS TCP/IP
Presentation: allow applications to interpret meaning of data, e.g. encyption, compression
Session:
What is encapsulation in networking?
Encapsulaion is a method of designing modular communication protocols in which logically separate functions in the network are abstracted from their underlying structures by inclusion or information hiding within higher level objects
Explain network architecture:
Client - Server
There is an always-on host, called the server, which services requests from many other hosts called clients (e.g. in a web application there is an always-on web server services requests from a browser running on client hosts
Clients do not directly communicate with each other
The server has a fixed, well-known address. called an IP address.
Servers usually reside on data centres for scaling
Explain network architecture:
Peer to Peer (P2P)
There is no always-on server, arbitrary end systems (peers) directly communicate and request/provide service to the peers.
P2P self-scales, new peers bring new service capacity and demand
Peers are intermittently connected and change IP addresses
Decentralizes structure and complex management
What is a processes in networking?
A program while executing is a process
Processes communicate within the same host using inter-process communication defined by the OS
Processes communicate in different end systems (potentially running different OSs) by exchanging messaged across a communication network
Describe inter-process communication?
In the context of a communication session between a pair of process that initiated the communication (that is, initially contacts the other process at the beginning of the session) is labelled as the client. The process that waits to be contacted to begin the session is the server. In P2P architectures, end systems have both client and server processes
What is a socket in terms of networking?
The interface between the process and the network is called a socket.
Socket is the software interface between the application layer and the transport layer.
It is also called the application Programming interface (API) between the application and the network.
How is the host identified on the internet?
In the internet, the host is identified by its IP address. The process is identified by a port number
