| 摘要 |
PURPOSE:To prevent the permanent circulation of a specific small loop by counting the number of detours in an autonomous spread type double loop transmission system. CONSTITUTION:Terminal devices are connected to the double loop transmission line through transmission controllers 11-16 and 21-26. Either a large loop 1 or 2 is utilized normally for transmission. If a specific line or transmission controller is at fault a large loop check (for loop 1 or 2) and small loop check (check among adjacent transmitters, e.g., check of a small loop among devices 22, 23, 12 and 13) are executed to form automatically the loopback constitution. If transmitters 14, 21 are at fault detour transmission lines 200, 300 for the loopback take part in the transmission line and a packet is circulated permanently within this small loop. Thus, the packet is provided with an area counting the number of detours and when the number reaches a prescribed number or over, the transmission of the said packet is stopped. |
