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| 作者：不明 来源：www.pccode.net 整理 发布时间：2007-1-24 15:24:23 发布人：wongrs | |
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y high speed data transport. Narrowband ISDN is circuit switched oriented. The B channel is the elemental circuit-switching unit. ISDN Terminal Equipment Two basic types of equipment TE1: Specialized ISDN terminal, including computer equipment or telephones. It is used to connect to ISDN through a four wire, twisted pair digital link. TE2: NON ISDN terminal such as data terminal equipment (DTE) that predates the ISDN standards. A TE2 connects to ISDN through a terminal adapter (TA). An ISDN (TA) can be either a standalone device or a board inside the TE2. ET:Exchange Termination: This is the local phone company's logical connection from your telephones to the phone network ISDN Network Termination Devices Intermediate Devices NT1: Treated as customer premises equipment (CPE) NT2: Typically found in digital private branch exchanges (PBXs). At the layer2 and layer3 NT1/2: combined functions of NT1 and NT2 ISDN Reference Point R: It is between non-ISDN equipment and a TA S: It is between user terminals and an NT2 T: It is between NT1 and NT2 U: It is between NT1 devices and line termination equipment in a carrier network. Customer Premise Equipment Are devices physically located on the subscriber's premise: Such as telephones and modems. Demarc The demarcation point is the junction at which the CPE ends and the local loop portion of the service begins. DTE and DCE The WAN physical layer describes the interface between the data terminal equipment DTE and the data circuit terminating equipment DCE. Typically the DCE is the service provider, and the DTE is the attached device. DTE Data terminal equipment: Device at the user end of a user network interfaces that serves as a data source, destination or both and connects through a DCE device. CO Central Office: Local telephone company office to which all-local loops in a given area connect and in which circuit switching of subscriber. LMI Local Management Interface: A signaling standard between the CPE device and FR switch that is responsible for managing the connection and maintaining status between the devices PAP and CHAP Router> EXEC Mode Router# Pri
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