Information about Parc Universal Packet
The PARC Universal Packet (commonly abbreviated to PUP, although the original documents usually use Pup) was one of the two earliest internetwork protocol suites; it was created by researchers at Xerox PARC in the mid-1970s. (Technically, the name "PUP" only refers to the internetwork-level protocol, but it is also applied to the whole protocol suite.) The entire suite provided routing and packet delivery, as well as higher level functions such as a reliable byte stream, along with numerous applications.
The origins of the PUP suite lie in two developments; in the same events in the early 1970s as the very earliest stage of the development of TCP/IP (see History of the Internet), and the creation of the Ethernet local area network at PARC. However, the development of PUP split off because Xerox PARC wished to move ahead with implementation, for in-house use. The fundamental design of the PUP suite was substantially complete by 1974.
In the 1980s Xerox used PUP as the base for the Xerox Network Services (XNS) protocol suite; some of the protocols in the XNS suite (e.g. the Internetwork Datagram Protocol) were lightly modified versions of the ones in the PUP suite, but others are quite different, reflecting the experience gained with PUP.
Unlike TCP/IP, socket fields were part of the full network address in the PUP header, so that upper-layer protocols did not need to implement their own demultiplexing; PUP also supplied packet types (again, unlike IP). Also, an optional 2-byte checksum covered the entire packet.
PUP packets were up to 554 bytes long (including the 20 byte PUP header), and the checksum. This was a smaller packet size than IP, which requires all hosts to support at least 576 (but supports packets of up to 65K bytes, if the hosts support them); individual PUP host pairs on a particular network might use larger packets, but no PUP router was required to handle them. Larger packets could be fragmented.
A protocol named the Gateway Information Protocol (a remote ancestor of RIP) was used as both the routing protocol, and for hosts to discover routers.
PUP also included a simple echo protocol at the internetwork layer, similar to IP's ping, but operating at a lower level.
Once RTP had started the connection, BSP took over and managed the data transfer. Like TCP, BSP's semantics and operation were in terms of bytes; this was discarded in favour of packets for the equivalent protocol in XNS, Sequenced Packet Protocol.
Others were novel, including protocols for printer spooling, copying disk packs, page-level remote access to file servers, name lookup, remote management, etc (although some of these capabilities had been seen before, e.g. the ARPANET already made heavy use of remote management for controlling the Interface Message Processors which made it up).
The Gateway Information Protocol's descendant, RIP, (somewhat modified to match the syntax of addresses of other protocol suites), remains in wide use today in other protocol suites. One version of RIP served as one of the initial so-called interior gateway protocols for the growing Internet, before the arrival of the more modern OSPF and IS-IS. It is still in use as an interior routing protocol, in small sites with simple requirements.
This article may contain original research or unverified claims.
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TELNET (TELecommunication NETwork) is a network protocol used on the Internet or local area network (LAN) connections.
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The origins of the PUP suite lie in two developments; in the same events in the early 1970s as the very earliest stage of the development of TCP/IP (see History of the Internet), and the creation of the Ethernet local area network at PARC. However, the development of PUP split off because Xerox PARC wished to move ahead with implementation, for in-house use. The fundamental design of the PUP suite was substantially complete by 1974.
In the 1980s Xerox used PUP as the base for the Xerox Network Services (XNS) protocol suite; some of the protocols in the XNS suite (e.g. the Internetwork Datagram Protocol) were lightly modified versions of the ones in the PUP suite, but others are quite different, reflecting the experience gained with PUP.
Basic internetwork protocol
The main internetwork layer protocol was PUP, which roughly corresponds to the Internet Protocol (IP) layer in TCP/IP. A full PUP network address consisted of an 8-bit network number, an 8-bit host number, and a 16-bit socket number. The network number had a particular special value which meant 'this network', for use by hosts which did not (yet) know their network number.Unlike TCP/IP, socket fields were part of the full network address in the PUP header, so that upper-layer protocols did not need to implement their own demultiplexing; PUP also supplied packet types (again, unlike IP). Also, an optional 2-byte checksum covered the entire packet.
PUP packets were up to 554 bytes long (including the 20 byte PUP header), and the checksum. This was a smaller packet size than IP, which requires all hosts to support at least 576 (but supports packets of up to 65K bytes, if the hosts support them); individual PUP host pairs on a particular network might use larger packets, but no PUP router was required to handle them. Larger packets could be fragmented.
A protocol named the Gateway Information Protocol (a remote ancestor of RIP) was used as both the routing protocol, and for hosts to discover routers.
PUP also included a simple echo protocol at the internetwork layer, similar to IP's ping, but operating at a lower level.
Transport layer protocols
To establish a transport connection, two protocols came into play. The first, the Rendezvous and Termination Protocol (RTP), which was used to initiate communication between two entities, as well as manage and terminate the connection. The second was the primary transport layer protocol, Byte Stream Protocol (BSP), which was analogous to TCP.Once RTP had started the connection, BSP took over and managed the data transfer. Like TCP, BSP's semantics and operation were in terms of bytes; this was discarded in favour of packets for the equivalent protocol in XNS, Sequenced Packet Protocol.
Application protocols
PUP supported a large number of applications. Some of them, such as Telnet and File Transfer Protocol, were basically the same protocols as used on the ARPANET (much as occurred with the TCP/IP suite).Others were novel, including protocols for printer spooling, copying disk packs, page-level remote access to file servers, name lookup, remote management, etc (although some of these capabilities had been seen before, e.g. the ARPANET already made heavy use of remote management for controlling the Interface Message Processors which made it up).
Impact
In showing that internetworking ideas were feasible, in being influential in the early work on TCP/IP, and as the foundation for the later XNS protocols, PUP was very influential. However, its biggest impact was probably as a key component of the office of the future model first demonstrated at Xerox PARC; that demonstration would not have been anything like as powerful as it was without all the capabilities that a working internetwork provided.The Gateway Information Protocol's descendant, RIP, (somewhat modified to match the syntax of addresses of other protocol suites), remains in wide use today in other protocol suites. One version of RIP served as one of the initial so-called interior gateway protocols for the growing Internet, before the arrival of the more modern OSPF and IS-IS. It is still in use as an interior routing protocol, in small sites with simple requirements.
See also
Further reading
- David R. Boggs, John F. Shoch, Edward A. Taft, Robert M. Metcalfe, Pup: An Internetwork Architecture (IEEE Transactions on Communications, COM-28(4):612-624, April, 1980)
References
- Edward A. Taft, Robert M. Metcalfe, Pup Specifications (Xerox Parc, Palo Alto, June, 1978 and October, 1975)
- Edward A. Taft, State Machine for Rendezvous/Termination Protocol (Xerox Parc, Palo Alto, July, 1978 and October, 1975)
- Edward A. Taft, Naming and Addressing Conventions for Pup (Xerox Parc, Palo Alto, July, 1978 and October, 1975)
- Edward A. Taft, Pup Error Protocol (Xerox Parc, Palo Alto, July, 1978 and October, 1975)
- Jon A. Hupp, Pup Network Constants (Xerox Parc, Palo Alto, July, 1979)
Internetworking involves connecting two or more distinct computer networks or network segments together to form an internetwork (often shortened to internet), using devices which operate at layer 3 (Network layer) of the OSI Basic Reference Model (such as routers or
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A protocol stack (sometimes communications stack) is a particular software implementation of a computer networking protocol suite. The terms are often used interchangeably.
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PARC (Palo Alto Research Center, Inc.), formerly Xerox PARC, is a research and development company in Palo Alto, California that began as a division of Xerox Corporation. It was founded in 1970, and incorporated as a wholly owned subsidiary of Xerox in 2002.
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Centuries: 19th century - 20th century - 21st century
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1975 1976 1977 1978 1979
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- The 1970s decade refers to the years from 1970 to 1979, also called
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1975 1976 1977 1978 1979
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- The 1970s decade refers to the years from 1970 to 1979, also called
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Routing (or routeing) is the process of selecting paths in a network along which to send data or physical traffic. Routing is performed for many kinds of networks, including the telephone network, the Internet, and transport networks.
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A reliable byte stream is a common service paradigm in computer networking; it refers to a byte stream in which the bytes which emerge from the communication channel at the recipient are exactly the same, and in the exact same order, as they were when the sender inserted them into
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The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It has also been referred to as the TCP/IP protocol suite, which is named after two of the most important protocols in it:
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first multiprotocol wide area network called the NASA Science Internet, or NSI. NSI was established to provide a total integrated communications infrastructure to the NASA scientific community for the advancement of earth, space and life sciences.
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Ethernet is a family of frame-based computer networking technologies for local area networks (LANs). The name comes from the physical concept of the ether. It defines a number of wiring and signaling standards for the physical layer, through means of network access at the Media
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local area network (LAN) is a computer network covering a small geographic area, like a home, office, or group of buildings. The defining characteristics of LANs, in contrast to Wide Area Networks (WANs), include their much higher data transfer rates, smaller geographic range, and
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1971 1972 1973 - 1974 - 1975 1976 1977
Year 1974 (MCMLXXIV
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Year 1974 (MCMLXXIV
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Xerox Corporation
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Founded Rochester, New York, USA (1906)
Headquarters Stamford, Connecticut, USA Offices in Rochester, New York
Key people Anne M. Mulcahy, Chairman & CEO
Ursula Burns, President
Larry Zimmerman, CFO
Gary R.
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Public (NYSE: XRX )
Founded Rochester, New York, USA (1906)
Headquarters Stamford, Connecticut, USA Offices in Rochester, New York
Key people Anne M. Mulcahy, Chairman & CEO
Ursula Burns, President
Larry Zimmerman, CFO
Gary R.
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Xerox Network Services (commonly XNS) was a protocol suite promulgated by Xerox, which provided routing and packet delivery, as well as higher level functions such as a reliable stream, and remote procedure calls.
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protocol is a convention or standard that controls or enables the connection, communication, and data transfer between two computing endpoints. In its simplest form, a protocol can be defined as the rules governing the syntax, semantics, and synchronization of communication.
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Internet protocol may refer to:
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- The Internet Protocol, a data-oriented protocol used for communicating data across a packet-switched internetwork
- The Internet protocol suite, a set of communications protocols that implement the protocol stack on which the Internet runs
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In computer networking, the term network address may refer to one of the following:
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- A network layer address, i.e. a logical address such as an IP address, X.25/X.21 address or IPX address.
- The base address of a classful address range to an organization, i.e.
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In information technology, Header refers to supplemental data placed at the beginning of a block of data being stored or transmitted, which contain information for the handling of the data block.
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Routing Information Protocol (RIP) was one of the most commonly used interior gateway protocol (IGP) routing protocols on internal networks (and to a lesser extent, networks connected to the Internet), which helps routers dynamically adapt to changes of network connections by
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A routing protocol is a protocol that specifies how routers communicate with each other to disseminate information that allows them to select routes between any two nodes on a network. Typically, each router has a priori knowledge only of its immediate neighbors.
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ping is a computer network tool used to test whether a particular host is reachable across an IP network. It works by sending ICMP “echo request” packets to the target host and listening for ICMP “echo response” replies.
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The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. TCP provides reliable, in-order delivery of a stream of bytes, making it suitable for applications like file transfer and e-mail.
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For the packet switched network, see .
TELNET (TELecommunication NETwork) is a network protocol used on the Internet or local area network (LAN) connections.
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FTP or File Transfer Protocol is used to transfer data from one computer to another over the Internet, or through a network.
Specifically, FTP is a commonly used protocol for exchanging files over any network that supports the TCP/IP protocol (such as the Internet or
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Specifically, FTP is a commonly used protocol for exchanging files over any network that supports the TCP/IP protocol (such as the Internet or
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The ARPANET, developed by DARPA of the United States Department of Defense, was the world's first operational packet switching network, and the predecessor of the global Internet.
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Interface Message Processor (IMP) was the packet-switching node used to connect computers to the original ARPANET in the late 1960s and 1970s. The protocol is defined in RFC 1.
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The office of the future is a concept dating from the 1940s. It is also known as the "paperless office". After thirty years of unfulfilled prophecies the phrase "paperless office" has been discredited somewhat.
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An interior gateway protocol (IGP) is a routing protocol that is used within an autonomous system.
In contrast an exterior gateway protocol is for determining network reachability between autonomous systems (AS) and makes use of IGPs to resolve route within an AS.
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In contrast an exterior gateway protocol is for determining network reachability between autonomous systems (AS) and makes use of IGPs to resolve route within an AS.
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Internet is a worldwide, publicly accessible series of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government
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