ASTR combines the merits of proactive routing protocol and on-demand routing protocol because subarea tree has the function of routing selection.
由于分区树具有路由选择功能，所以ASTR结合了先应式路由协议和按需路由协议的优点。
2
ASTR belongs to hierarchical routing protocol: it divides the whole network into many subareas logically through establishing subarea trees and each subarea is composed of a tree.