Browse Prior Art Database

Ring Network Employing the Locomotive Concept

IP.com Disclosure Number: IPCOM000038627D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 4 page(s) / 34K

Publishing Venue

IBM

Related People

Boettiger, H: AUTHOR [+4]

Abstract

As it permits the simultaneous transmission of several data frames led by a locomotive, the locomotive concept is advantageous for short messages of, say, 320 data bits, for voice packets and/or rings of, say, 200 km. The frames are sent and transmitted, respectively, by one or more nodes on the ring. Also suitable for this purpose are optical fibers permitting transmission frequencies of, say, 200 Mb/sec. This article describes a simplex and a duplex locomotive mechanism with multiple locomotives, wherein data frames may be reused by other nodes. The locomotive simplex ring has a node generating locomotive frames LOC (Fig. 1) at a given frequency. During initialization, a first (primary) generator starts transmitting. A second generator starts operating only after the packet train has arrived at or passed its node.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 35% of the total text.

Page 1 of 4

Ring Network Employing the Locomotive Concept

As it permits the simultaneous transmission of several data frames led by a locomotive, the locomotive concept is advantageous for short messages of, say, 320 data bits, for voice packets and/or rings of, say, 200 km. The frames are sent and transmitted, respectively, by one or more nodes on the ring. Also suitable for this purpose are optical fibers permitting transmission frequencies of, say, 200 Mb/sec. This article describes a simplex and a duplex locomotive mechanism with multiple locomotives, wherein data frames may be reused by other nodes. The locomotive simplex ring has a node generating locomotive frames LOC (Fig. 1) at a given frequency. During initialization, a first (primary) generator starts transmitting. A second generator starts operating only after the packet train has arrived at or passed its node. The LOC frames circle around the ring. A node with a packet ready for transmission attaches that packet D1 to the LOC with an end-of- train delimiter EOT. The next station on the ring, which is ready for transmission, replaces the end-of-train sequence by its packet D2, and so on (Fig.
2). This generates a packet train up to a predetermined total length for the same or for different destination nodes. Each station therefore monitors the current train length, estimating in the time between frames the remaining growth potential for appending additional frames. An end-of-train condition enables the node to append the frame within a couple of byte times. During the first revolution of the train on a simplex ring, all downstream packets pass their destination node, i.e., all packets with a target between the source and the locomotive generator. When passing the generator, the train is marked as starting its revolution for delivery of all upstream packets, i.e., all packets with a target between the locomotive generator and the source. After completion of the second revolution, the train is purged as a whole. A preferred embodiment of fiber-optic networks uses dual fibers, one fiber for each direction.

This is very advantageous for the locomotive ring approach. In a dual locomotive scheme, two counter-rotating rings are used, with locomotive generators controlling the clockwise and counterclockwise transmission. By selecting the appropriate (downstream) ring, it is possible to have the trains revolve only once before purging instead of twice as previously. In this case, each node must know the positions of the various nodes relative to its own position and those of the locomotive generator. It is possible to install or activate a larger number of locomotive generators reflecting the hierarchical organization of the ring, e.g., with multi-lobe nodes or subrings, or to have different classes of packets, such as voice, message, data set or image packets. Repeater nodes simply pass the train. Stations identifying their own address as a destination address in one of the frames copy th...