A.IP業(yè)務(wù)B.窄帶業(yè)務(wù)C.ATM業(yè)務(wù)D.寬帶業(yè)務(wù)
A.IP over PDHB.IP over SDHC.IP over ATMD.IP over WDM
A.二層B.三層C.四層D.五層