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JANUS interface specifications (RFC0745)

IP.com Disclosure Number: IPCOM000003792D
Original Publication Date: 1978-Mar-30
Included in the Prior Art Database: 2000-Sep-13
Document File: 9 page(s) / 21K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

M. Beeler: AUTHOR


1.1. Motivation

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 13% of the total text.

NWG/RFC# 745 MDB2 30-MAR-78 43649

JANUS Interface Specifications

Network Working Group Michael Beeler

Request for Comments 745 BBN

NIC 43649 30 March 1978

PRTN 245

JANUS Interface Specifications

(Symmetrical, 1822-like Interface)


1.1. Motivation

A need arose in the Packet Radio project for specification of an

interface between Packet Radio units and other equipment. This paper is

to meet BBN's responsibility to supply that specification. It is our

hope that it will find application in other areas as well.

1.2. Historical Relationship to 1822

The ARPANET employs a network of switching nodes, called IMPs, to

provide interconnection among user equipment, called hosts. A uniform

means of connecting a host to an IMP is specified in BBN Report Number

1822. Consequently, this interface has become known as an 1822


As the need to interconnect new types of devices has grown, it has

become attractive to implement an 1822-like interface on each end of

pairs of devices which are to communicate. The devices are then

connected electrically, and communication can take place in spite of

differences in processing speed, word length, signal levels and so forth

in the two devices. A part of Report 1822 reads as follows.

"The technique of transferring information between the Host and the

IMP is identical in each direction; we will, therefore, refer to the

sender and the receiver without specifying the Host or IMP


[BBN Report Number 1822, 12/75 revision, page 4-2.]

Unfortunately, Report 1822 does not specify a completely symmetrical

interface. Although there is a high degree of symmetry, some aspects

are peculiar to the IMP side and some to the host side. Therefore, two

interfaces constructed to connect to IMPs may not function connected to

each other. In what follows, the unsymmetrical aspects are respecified

in a way which will accomplish full interchangeability.

The interface specified here is called the JANUS interface, to

distinguish it from the Report 1822 interface.

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NWG/RFC# 745 MDB2 30-MAR-78 43649

JANUS Interface Specifications

1.3. Terminology

The terms, "IMP" and "host," are not relevant in the present context.

Sections of Report 1822 such as Appendix B are conveniently

re-interpreted by substituting "foreign interface" and "home interface,"



Report 1822 ad...