2023-09-07
Introduction
Summary
keywords
TODO
HW
What is the server setup of www.gist.ac.kr Server: HTTP nginx
Today's P2P using service : Skype, Bittorrent, Bitcoin,
Microsoft in Windows 10 uses a proprietary peer-to-peer technology called "Delivery Optimization" to deploy operating system updates using end-users PCs
Exercise*
Next time P2P
Recap
Traceroute uses ICMPg protocol (same protocol as ping command)
Throughput is different to bandwidth #todo 1: what is the difference?
#todo 2 : do the excercises
Protocols
so many different machines, medias, data... How do they communicate?
We divide each services as layers each layer
OSI layer model. (just in the theory) 7 layers.
TCP/IP layer model. (of today's Internet) 5 layer model.
Application
transport
network
link
physical
4 lower layers (transport - physical) are implemented in each OS. Application layers are implemented in server software or browser.
Service layering
![[../images/20230907132645.png]]
Attach a header for each layer, and pass it to the lower layer. Router delivers the packet
Each chunks have different names
in transport layer :
Messages are wrapped with header to make a segment of the layer
header_transport + message = segment
in network layer :
header_network + segment = datagram
in link layer :
header_link + datagram = frame
Switch do not consider about network layer They only care link layer & physical layer Router do consider about network layer.
Examples
wireshark using examples
Chapter 2. Application layer
keywords
Web, HTTP, SMTP, IMAP, DNS, P2P, video streaming, socket programming(using UDP & TCP)
Goals
conceptual & implementation of application layer protocols.
This semester makes a network app
text messaging, email, multi-user network games, streaming stored video, p2p, skype, zoom, internet search, remote login,
run on end systems.
communicate over network
encapsulate
no need to write software for network-core device
Client-Server paradigm
server
always-on host
permanent OP address
clients
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