calls at the time of failure are lost. Dynamic routing finds the least utilized paths
among many intermediate switches. Hierarchical routing can also provide restora-
tion, but generally in highly connected networks dynamic routing provides sig-
nificantly more paths than methods based on hierarchical routing and provides the
same degree of restoration with more efficient use of capacity.
Ethernet-Layer Spanning Tree Protocol The spanning tree protocol gener-
ates paths in Ethernet networks via distributed signaling among switches. The
principal development for spanning tree protocols was to avoid loops in Ethernet
networks. However, it also generates a minimum-hop path and serves as a restora-
tion method after topology updates settle. Rapid spanning ...