单项选择题
A.1+1备份方案 B.1+1互助方案 C.N+1备份方案 D.N+2互助方案
A.M3UA_LINK_UNESTABLISH B.M3UA_LINK_DOWN C.M3UA_LINK_INACTIVE D.3UA_LINK_DEACTIVE
A.WSMU B.WIFM C.WMGC D.WBSG