Network class 1

1.  What's the Internet

 

• millions of connected computing devices

            • hosts = end systems

            • running network apps

 

• communication links

            • fiber, copper, radio, satelite

            • transmission rate : bandwidth(Realizable bits per time unit)

                                                          

 

• Packet switches : forward packets

            • routers and switches

 

• Internet : "network of networks"

            • interconnected ISPs

 

• Protocols control sending, receiving of msgs

 

• Internet standards

            • RFC, IETF

 

 

2.  What's a protocol?

 

• protocols define format, order of msgs sent and received among network entities, and actions taken on msg transmission, receipt

 

 

3.  A closer look at network structure

 

• network edge

            • hosts : clients and servers

            • servers often in data centers

 

• access networks, physical media

            • wired, wireless communication links

 

• network core

            • interconnected routers

            • network of networks

 

 

4.  Access net : digital subscriber line (DSL)

 

 

• use existing telephone line to central office DSLAM

           - data over DSL phone line goes to Internet

           - voice over DSL phone line goes to telephone net

• Mbps upstream transmission rate (typically < 1 Mbps)

• downstream transmission rate (typically < 10Mbps)

 

5.  Access net : cable network

 

 

• HFC : hybrid fiber coax

             - 30 Mbps downstream transmission rate, 2 Mbps upstream transmission rate

 

6.  Access net : home network

 

- A router binds things together and connects them to a network

 

7.  Enterprise access networks (Ethernet)

 

- Router connects directly to ISP without going through phone or cable company

 

8.  Wireless access networks

- shared wireless access network connects end system to router

 

• WiFi (typically inside)

• wide-area wireless access (3G, 4G, LTE) (typically outside)