ETSI ETR 257-1996 数字业务节点(SN)的V接口.在接入网(ANs)的接入安排中用于Vb5参考点的现有协议规范的适用性识别
V Interfaces at the Digital Service Node (SN); Identification of the Applicability of Existing Protocol Specifications for a Vb5 Reference Point in an Access Arrangement with Access Networks (ANs)