Motivation For Internetworking

Motivation for Internetworking • Most networks are independent entities • Networking is old idea • Internetworking is more than 25 years old – Heterogeneous interconnect networks – Network hardware details hidden

© MMII JW Ryder

CS 428 Computer Networks

1

Open Systems Interconnection • Open System = Publicly available specifications • Proprietary Communication systems = One vendor, selfserving • Our network benefits from OSI standards

© MMII JW Ryder

CS 428 Computer Networks

2

OSI Why? • “More importantly, the entire technology has been designed to foster communication between machines with diverse hardware architectures, to use almost any packet switched network hardware, and to accommodate multiple computer operating systems.” Doug Comer, page 1 • Would that the world were so were so facile.

© MMII JW Ryder

CS 428 Computer Networks

3

TCP/IP Internet • Advanced Research Projects Agency (ARPA) – Defense Advanced Research Projects Agency (DARPA) in mid-80’s

• ARPA technology defines a set of network standards that specify how computers communicate • Set of conventions for interconnecting and routing • At one point, all addresses were kept in a single file © MMII JW Ryder

CS 428 Computer Networks

4

TCP/IP • Standards & conventions called Protocols • TCP/IP is a blend of Transmission Control Protocol and Internet Protocol • TCP/IP Internet Protocol Suite • Across any set of interconnected networks

© MMII JW Ryder

CS 428 Computer Networks

5

TCP/IP • Forms base for a global internet • An internet = private internets that use TCP/IP • The Internet = The Global Internet • Many U.S. gov’t agencies have funded the Internet development • The ARPA/NSF Internet – The TCP/IP Internet – The global Internet – The Internet © MMII JW Ryder

CS 428 Computer Networks

6

Application Level Internet Services • To user, TCP/IP appears to be a set of application programs • Interoperability - the ability of diverse computing systems to cooperate in solving computational problems • Internet application programs demonstrate a high degree of interoperability

© MMII JW Ryder

CS 428 Computer Networks

7

Applications • Electronic mail • File transfer • Remote login

© MMII JW Ryder

CS 428 Computer Networks

8

Network Level Internet Services • Programmer’s view provides 2 broad services • Connectionless Packet Delivery System • Reliable Stream Transport Service

© MMII JW Ryder

CS 428 Computer Networks

9

What Distinguishes TCP/IP? • Network Technology Independence – Datagram

• Universal Interconnection – Addresses universally recognized throughout the Internet

• End to End Acknowledgements – Others are just between stations (intermediate routing nodes)

• Application protocol standards © MMII JW Ryder

CS 428 Computer Networks

10

History & Scope of the Internet • ARPA began internet technology in mid-70’s – Architecture & protocols taking current form ‘77-’79 (ARPANET)

• Point to Point leased line interconnection, radio networks, satellites • Funding $$$ prevalent in ‘79, many researchers

© MMII JW Ryder

CS 428 Computer Networks

11

ICCB • Internet Control and Configuration Board • ARPA formed informal committee to coordinate – Design of protocols – Architecture

• Met through about 1983

© MMII JW Ryder

CS 428 Computer Networks

12

Global Internet • Began around 1980 • ARPA started converting machines attached to its research computers with TCP/IP • ARPANET became the backbone of new Internet • January 1983 Office of Secretary of Defense mandated that all computers connected to the long haul network use TCP/IP © MMII JW Ryder

CS 428 Computer Networks

13

ARPANET/BSD/BBN • Split, 1 for research, 1 for military research • Made ARPANET available to universities at low cost • At time, most CS departments were using Unix – University of California’s Berkeley Software Distribution, Berkeley Unix, BSD Unix • ARPA funded Bolt Beranek and Newman (BBN) to implement its TCP/IP protocols for use with Unix • ARPA funded Berkeley to integrate the protocols with its software distribution • Ergo, ARPA able to reach very high percentage (90%) of all university CS departments

© MMII JW Ryder

CS 428 Computer Networks

14

BSD Unix • Offered a set of networking functions that resembled Unix services used on single machines • Experienced Unix users have no problems learning TCP/IP networking interfaces because they are so similar • New operating system abstraction called the socket – Allows application programs to access communications protocols © MMII JW Ryder

CS 428 Computer Networks

15

Internet Youth • 1985 - Six supercomputer centers • 1986 - Expanded to funding wide area backbone called NSFNET • Tied above to ARPANET • NSF in 1986 provided seed money for regional networks • All NSF funded networks use TCP/IP • 1987 (7 years later) the Internet spanned hundreds of individual networks in the U.S. and Europe • Connected nearly 20.000 computers, by late 1987 estimate was that the Internet was growing at 15% per month © MMII JW Ryder

CS 428 Computer Networks

16

Internet Teenager • 1994 - the Internet reached over 3,000,000 computers in 61 countries • Rapid expansion problems of an unanticipated scale • Motivated researchers to find techniques to manage large, distributed resources • Original design – Names and addresses of all computers attached to the Internet were kept in 1 file – Mid-80’s apparent central data base not right solution © MMII JW Ryder

CS 428 Computer Networks

17

Domain Name System • Name servers answer queries about name/address pairs • No single machine contains entire name base

© MMII JW Ryder

CS 428 Computer Networks

18

Internet Architecture Board (IAB)

• TCP/IP internet protocol did not arise from a specific vendor or from a recognized professional society • Who sets the technical standard? • The IAB provides focus and coordination for – – – –

Research Development Guides Evolution IAB is almost exclusively volunteers

© MMII JW Ryder

CS 428 Computer Networks

19

IAB Activities • Formed in 1983 from reorganized ICCB • First 6 years, it changed from ARPA specific to autonomous organization • Each member of IAB chaired a specific Internet Task Force – Approx. 10 task forces – Charters from how traffic load from an application affects the Internet to short term Internet Engineering problems

© MMII JW Ryder

CS 428 Computer Networks

20

IAB Activities • Did not manage a large budget • Volunteers • Members responsible for recruiting volunteers to serve on task forces – usually from research organizations of industry where TCP/IP was used

• Active researcher participated because – Serving on task force allowed learning about new research problems – Could have direct influence on standards © MMII JW Ryder

CS 428 Computer Networks

21

IAB ReOrg • Summer 1989 • Political and Commercial realities • Researchers moved from IAB Board to subsidiary group • New IAB Board with representatives from wider community

© MMII JW Ryder

CS 428 Computer Networks

22

IAB Organization The Board IRTF

IETF

IRSG

IESG area 1

Research Groups

© MMII JW Ryder

area n

Working Groups

CS 428 Computer Networks

23