Computing – Communications and Networks

Inside the Internet

 Between end systems
 TCP protocol for reliable transmission
 Inside the network core
 IP protocol: forwarding packets between routers
 Between routers or between end system and router
 high speed link: ATM, POS (Packet over SONET), satellite links
 access network: Ethernet, modem, xDSL, HFC


Network structure
 network edge: applications and hosts
 network core:
 routers
 network of networks
 access networks, physical media: communication links


The network edge:

 end systems (hosts):
 run application programs
 e.g., WWW, email
 at “edge of network”
 client/server model
 client host requests, receives service from server
 e.g., WWW client (browser)/ server, email client/server
 peer-peer model:
 symmetric host interaction
 e.g. teleconferencing