问题：

[多选] Which two statements are true about IS -IS routing?（）

A . Based on the default timers, OSPF d etects a failure faster than IS - IS does.
B . OSPF default timers permit more tuning than IS - IS does.
C . IS - IS is more efficient than OSPF in the use of CPU resources.
D . OSPF is more scalable than IS - IS because of its ability to identify normal, stub, an d NSSA areas.
E . IS - IS and OSPF are both Open Standard, link - state routing protocols which support VLSM.