Saturday, May 14, 2011

History of OSI....

Prior to OSI, networking was largely either government-sponsored (ARPANET, CYCLADES) or vendor-developed and proprietary, the latter effort consisting of protocol standards such as SNA, Appletalk, NetWare and DECnet. In the UK work on the Experimental Packet Switched system circa 1973, the need to define so called higher level protocols above the HDLC link level communications protocol and the content of an NCC (UK) publication 'Why Distributed Computing' resulting from considerable research into future configurations for computer systems resulted in the UK presenting the case for an International Standards Committee to cover this area at the ISO meeting in Sydney in March 1977. OSI was hence an industry effort, attempting to get industry participants to agree on common network standards to provide multi-vendor interoperability. It was common for large networks to support multiple network protocol suites, with many devices unable to interoperate with other devices because of a lack of common protocols. However, while OSI developed its networking standards, TCP/IP came into widespread use on multivendor networks for internetworking, while on the local network level both Ethernet and token ring gained prominence.
The OSI reference model was a major advance in the teaching of network concepts. It promoted the idea of a consistent model of protocol layers, defining interoperability between network devices and software. The OSI model was defined in raw form in Washington DC in February 1978 by Hubert Zimmerman of France and the refined standard was published by the ISO in 1984.

LDAP intro...

elecommunication companies' understanding of directory requirements was well developed after some 70 years of producing and managing telephone directories. These companies introduced the concept of directory services to information technology and computer networking, their input culminating in the comprehensive X.500 specification,[2] a suite of protocols produced by the International Telecommunication Union (ITU) in the 1980s.
X.500 directory services were traditionally accessed via the X.500 Directory Access Protocol (DAP), which required the Open Systems Interconnection (OSI) protocol stack. LDAP was originally intended to be a lightweight alternative protocol for accessing X.500 directory services through the simpler (and now widespread) TCP/IP protocol stack. This model of directory access was borrowed from the DIXIE and Directory Assistance Service protocols.
Standalone LDAP directory servers soon followed, as did directory servers supporting both DAP and LDAP. The latter has become popular in enterprises, as LDAP removed any need to deploy an OSI network. Today, X.500 directory protocols including DAP can also be used directly over TCP/IP.
The protocol was originally created by Tim Howes of the University of Michigan, Steve Kille of Isode Limited, and Wengyik Yeong of Performance Systems International, circa 1993. Mark Wahl of Critical Angle Inc., Tim Howes, and Steve Kille started work in 1996 on a new version of LDAP, LDAPv3, under the aegis of the Internet Engineering Task Force (IETF). LDAPv3, first published in 1997, superseded LDAPv2 and added support for extensibility, integrated the Simple Authentication and Security Layer, and better aligned the protocol to the 1993 edition of X.500. Further development of the LDAPv3 specifications themselves and of numerous extensions adding features to LDAPv3 has come through the IETF.
In the early engineering stages of LDAP, it was known as Lightweight Directory Browsing Protocol, or LDBP. It was renamed with the expansion of the scope of the protocol beyond directory browsing and searching, to include directory update functions. It was given its Lightweight name because it was not as network intensive as its DAP predecessor and thus was more easily implemented over the internet due to its relatively modest bandwidth usage.
LDAP has influenced subsequent Internet protocols, including later versions of X.500, XML Enabled Directory (XED), Directory Service Markup Language (DSML), Service Provisioning Markup Language (SPML), and the Service Location Protocol (SLP).