1.1 What is the Internet? Flashcards
How are end systems connected together?
End systems are connected together by a network of communication links and packet switches.
Describe a packet switch job.
A packet switch takes a packet arriving on one end of its incoming communication links and forwards it on one of its outgoing communication links.
Packet switch examples.
- routers: typically used in network core
- link-layer switches: typically used in access networks.
How do end systs. access the Internet?
Through Internet service providers (ISPs)
General description of ISPs.
Each ISP is itself a network of packet switches and communication links.
The internet is all about connecting end systems to each other, so the ISPs that provide access to end systems must also be interconnected through national and international upper-tier ISPs.
Define upper-tier ISP.
An upper-tier ISP consists of high-speed routers interconnected with high-speed fiber-optic links.
Define protocol
A protocol 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 receipt of a message or other event.
