多项选择题
A. forms adjacencies with all neighbors
B. supports demand circuit routing
C. provides routing support for multiple network layer protocols
D. utilizes SPF algorithm
E. provides for network scalability by allowing the network to be separated into areas
F. three layers of hierarchical routing
单项选择题 How is network layer addressing accomplished in the OSI protocol suite?（）
单项选择题 What is the default metric used on IS -IS routers for each interface?（）
单项选择题 Which packet type is used to ackno wledge LSPs on point - to - point links and to request missing pieces of information in the IS - IS link -state database?（）