（1）普通汇聚到骨干汇聚的SR-TP隧道：工作隧道优先走汇聚环，保护隧

(1) Ordinary convergence to backbone convergence SR-TP tunnel: working tunnels prefer to use the convergence ring, and the protection tunnels are interconnected via the backbone convergence and cannot bypass the access ring; <BR>(2) the backbone convergence to the SR-TP tunnel of the metro core : The working tunnel does not use the interconnection link between the metropolitan area cores, and protects the tunnel through the metropolitan area core interconnection link, and does not detour through other metropolitan area cores and backbones;

(1) SR-TP tunnel that generally converges to the backbone: the work tunnel takes precedence to walk the convergence ring, protects the tunnel through the backbone convergence interconnection, can not bypass the access ring;<BR>(2) SR-TP tunnel where the backbone converges to the core of the metro: the working tunnel does not take the interconnect link between the core of the metro, protects the tunnel through the core interconnect link of the metro, does not bypass the core of other metro areas, the backbone converges;

(1) Sr-tp tunnel converging to backbone converging: the working tunnel preferentially goes through the converging ring to protect the tunnel from bypassing the access ring;<BR>(2) Sr-tp tunnel with backbone converging to metro core: the working tunnel does not take the interconnection link between Metro cores, and protects the tunnel from bypassing other metro cores and backbone converging through metro core interconnection link;<BR>