Chapter 10: The Basics of Networking

Summary of IP networking

• It's all based on numbers, not names
• It's always packets, all the time
• Names are just a layer over IP
• A local network becomes worldwide through the magic of routing

General Communication Properties

• Synchronous
• Asynchronous

General Communication Properties

• Broadcast
• Multicast
• Point-to-point

The Internet's Communications Properties

• Client/Server
• Any one communication is generally not extended but consists rather of many brief interactions
• Maps well to the idea of packet switching

The Internet's Communications Properties

• No guarantees as to timeliness, just to completeness (sometimes/maybe)
• Bufferbloat: https://en.wikipedia.org/wiki/Bufferbloat

IP is a bunch of numbers, not names

• IPv4, four bytes; IPv6, 16 bytes
• Names on the Internet are different; they are just a convention layered over IP, and are not fundamental to the actual operation of the Internet, just its utility

DNS

• It all starts at the root
• http://www.root-servers.org/

DNS

• The common TLDs: .edu, .gov, .com, .net, .org, .name, .info, ...

DNS

• World (ISO 3166): .uk, .ch, .jp, ...

DNS

• Unlimited, but it's not cheap: https://gtldresult.icann.org/application-result/applicationstatus

Alternative DNS

• http://en.wikipedia.org/wiki/Alternative_DNS_root
• http://namecoin.info/

IP Protocol

• TCP
• UDP
• ICMP

From Wikipedia (license)

LANs

• Ethernet to a fare-thee-well

Ethernet

• Originally all wired, all broadcast, all the time
• Now wired is all switched packets, and wireless is broadcast

DHCP

• Ethernet numbers are "static"
• IP numbers sometimes are static, often dynamic

Major IP services

• The World Wide Web; protocol is HTTP over ports 80 and 443

Major IP services

• Email sending; protocol is SMTP over port 25, 465, and 587
• Email receiving; protocols are POP and IMAP over ports 110/995, 143/993

Major IP services

• DNS; protocol is DNS over port 53 UDP and over port 53 TCP

Major IP services

• FTP; protocol is FTP over ports 20/21
• Peer-to-peer; protocols vary, BitTorrent is common, usually found from 6881-6889, though very flexible

How a URL is structured

• http://www.cs.fsu.edu/~langley/CGS2100/2014-Fall/index.html
• Actually refers to files on www.cs.fsu.edu in a directory structure
• /home/langley/public_html/CGS2100/2014-Fall/index.html

Before and after the web

• The Internet is older than WWW
• Before WWW, we had email, ftp;
• After WWW, the next big use of bandwidth was the development of P2P