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Protocol for Wrap Operation on Duplex Loop Communication System

IP.com Disclosure Number: IPCOM000050522D
Original Publication Date: 1982-Nov-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Sheldon, RJ: AUTHOR [+2]

Abstract

After two stations on a duplex loop have disconnected two intervening links of the loop and reconnected the remaining duplex lines into two simplex loops in a wrap operation, the stations use a protocol to signal each other that both links at the wrap point have been repaired and that the links can be reconnected in the duplex configuration. Each of the two stations at the wrap point attempts to send a message to the other station on one link. and it monitors the other incoming link for a corresponding message. When a station receives a message from the other station, it knows that the incoming link is operable. It then sends a different message to the other station across the wrap point. The new message may differ from the first message in a single bit position.

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Protocol for Wrap Operation on Duplex Loop Communication System

After two stations on a duplex loop have disconnected two intervening links of the loop and reconnected the remaining duplex lines into two simplex loops in a wrap operation, the stations use a protocol to signal each other that both links at the wrap point have been repaired and that the links can be reconnected in the duplex configuration. Each of the two stations at the wrap point attempts to send a message to the other station on one link. and it monitors the other incoming link for a corresponding message. When a station receives a message from the other station, it knows that the incoming link is operable. It then sends a different message to the other station across the wrap point. The new message may differ from the first message in a single bit position. When a station has received the second message it knows that both links have been restored, and the station then returns to the duplex configuration.

The drawing shows a conventional duplex system having representative secondary stations A and B. One loop 4 runs clockwise through each station, and one loop 5 runs counterclockwise' In this example, a fault has interrupted one or both loops at the links between stations A and B. In a conventional wrap operation, stations A and B form interconnections 6 and 7 that establish two simplex loops 8 and 9. Steps are then taken to repair the fault.

While the system is in the wrap configuration, statio...