Which three statements are correct about the differences in IS - IS and OSPF?（）

• A、IS - IS is more CPU - intensive than is OSPF
• B、For greater fine tuning there are more IS - IS timers
• C、IS - IS LSP con tains TLV fields and OSPF LSU contains the LSAs
• D、New additions to the protocol are easily implemented in OSPF but not with IS - IS
• E、OSPF has more area types than does IS - IS