· What did you learn in TDC 361 and 362? · What is a (communications) network? An interconnected structure that allows attached devices to communicate with each other · Client/Server Model · Network Protocols · Network Classifications: LAN, MAN, WAN etc. · Internetwork
· What did you learn in TDC 361 and 362?
· What is a (communications) network?
An interconnected structure that allows attached devices to communicate with each other
· Client/Server Model
· Network Protocols
· Network Classifications: LAN, MAN, WAN etc.
· Internetworking devices
· The Internet as an example
· Brief history
· Structure of the Internet
· RFC (Request for Comments)
· Network Architectures: OSI and TCP/IP
· Internetworking devices revisited
· Some Internet probing tools: ping and traceroute / tracert
· Conversion between different number systems
· IP Classful Addresses
Unit 1: Introduction to Internetworking
Internetworking devices: bridges, routers, gateways etc.
A collection of networks and routers that span many countries and uses the TCP/IP protocols to form a single, cooperative virtual network.
Intranet: connection of different LANs within an organization.
Main players in the Internet:
Started by U.S. research/military organizations:
(D)ARPA: (Defense) Advanced Research Projects Agency
funds technology with military usefulness
DoD: U.S. Department of Defense
early adaptor of Internet technology
NSF: National Science Foundations
funds university research
National backbone providers (NBPs)
interconnected through exchange points:
NAPs (Network Access Points) and MAEs (Metropolitan
Regional ISPs connects to the NBPs
Brief History of the Internet
1876: telephone (circuit-switching)
Development of Early Packet Switching Principles:
early 1960's concept of packet switching (Paul Baran)
1965: MIT's Lincoln Laboratory commissions Thomas Marill to study computer networking
1968: ARPAnet contract awarded to Bolt Beranek and Newman (BBN)
1969: ARPAnet has 4 nodes (UCLA, SRI, UCSB, U. Utah), connected by IMPs (Interface message processors); connected by 50 kbps lines
1971: 15 nodes and 23 hosts
Internetworking, and New and Proprietary Networks
1973: TCP/IP design.
First satellite link from California to Hawaii
First international connections to the ARPANET:England and Norway
1979: ARPAnet had about 100 nodes
1980s: DARPA funded Berkeley Unix, with TCP/IP
1980-81: BITNET (IBM protocols) and CSNET (NSF-funded)
Early 1980's: split ARPnet (research), MILNET (Military)
Proliferation of Networks:
1984: Domain Name Services (Mapping Domain names into IP addresses)
1986: NSFNET created (56kbps backbone)
1989: Internet passes 100,000 nodes
First proposal for World Wide Web
NSFNET backbone upgraded to T1 (1.544 Mbps)
Commercialization and the Web:
1990: Original ARPAnet disbanded
Fall 1991: CSNET discontinued
1991: Gopher released by University of Minnesota
1992: NSFNET backbone upgraded to T3 (44.736 Mbps)
March 1992: First MBONE (Multicast Backbone) video multicast
November 1992: First MBONE video multicast
Februray 1993: 1,776,000 hosts
May 1993: NSF solicited for bids and designated a series of NAPs (e.g. Chicago NAP is run by Ameritech)
April 30, 1995: NSFNet backbone disbanded
(See http://www.navigators.com/isp.html for excellent information and links about the architecture of the Internet)
Internet growth from 1981 through 2000 plotted on a log scale
Internet growth from 1981 through 2000
Some Internet-related organizations
The Internet SOCiety (ISOC) is a professional membership society with more than 150 organizational and 6,000 individual members in over 100 countries. It provides leadership in addressing issues that confront the future of the Internet, and is the organization home for the groups responsible for Internet infrastructure standards, including the Internet Engineering Task Force (IETF) and the Internet Architecture Board (IAB).
The IAB (Internet Architecture Board) is the Internet Society overseer of the technical evolution of the Internet. The IAB supervises the Internet Engineering Task Force (IETF), which oversees the evolution of TCP/IP, and the Internet Research Task Force (IRTF), which works on network technology.
The Internet Engineering Task Force (IETF) is a large open international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet. It is open to any interested individual.
Responsible for RFCs (Request for Comments, Internet Standards/drafts) which can be located at http://www.ietf.org/rfc.html
The Internet Corporation for Assigned Names and Numbers (ICANN) is the non-profit corporation that was formed to assume responsibility for the IP address space allocation, protocol parameter assignment, domain name system management, and root server system management function previously performed under U.S. Government contract by IANA (Internet Assigned Numbers Authority) and other entities.
Maturity levels of an RFC
Application = boss
Transport = secretary
Network Access = post office
ISO OSI Model
(ISO = International Standard Organization, OSI = Open Systems Interconnection)
An exchange using the OSI model: Encapsulation and Decapsulation
TCP/IP and OSI Model
IP: Internet Protocol
TCP: Transmission Control Protocol
UDP: User Datagram Protocol
Connection-oriented: a connection must be set up first. Data go in sequence
Connectionless: no need to set up a connection. Data may arrive out of sequence.
Figure 2-13 Relationship of layers and addresses in TCP/IP
Example: web browser implementing HTTP
Eg. TCP port 80 for web server
Interface. Eg. WINSOCK on PCs
Implemented in TCP and UDP software. HTTP uses TCP.
Eg. 220.127.116.11 (32- bit)
Implemented in IP software
Eg. Ethernet Medium Access Control (MAC) implemented in NIC card (Network Interface Card) and driver software
Eg. Ethernet address (48-bit)
Eg. Ethernet PHY layer. Implemented in NIC card
Figure 2-14 Physical addresses: identify and interface card (Link address, MAC address)
Eg. Ethernet: a broadcast network.
Figure 2-15 IP addresses (A logical address necessary for universal communication over the internet, and is independent of the underlying physical networks)
Note: We commonly uses names such as www.cs.depaul.edu (called Domain Names). To translate from names to IP addresses, needs to use DNS (Domain Name Service) implemented at the Application level.
A host is assigned a host number unique within a network
A router assigned an IP address per interface
Each network assigned an IP network number
Dotted Decimal Notation
Class A: Large networks
Class B: Medium networks
Class C: Small networks
Hostid with all 0’s or all 1’s are special.
Classful IP Addresses
Range of addresses in each class
Multihomed devices have different addresses for each interface