The SDH self-healing ring has now become one important network topolo gy for the synchronous optical transmission network because of its relatively high sur- vivability.The calculation of service capacity of the Self-healing ring is a vital base for the planning of ring network.On the basis of service capacity of the self-healing ring
this paper presents a caculation method of traffic flow
and caculation formula of traffic flow as well as restriction conditions for different self-healing rings are also given.