CCNA Vocabulary 1
August 12, 2011 in CCNA by ciscoguy
Below is list of terms you need to know for the CCNA exam.
| Access Link | The serial link (physical) that connects a Frame Relay device (such as a router) to a Frame Relay switch |
| Back-to-Back Link | A serial link connecting two routers without CSU/DSUs. One router used a DTE cable and the other uses a DCE cable. Typically used in labs. |
| CSU/DSU | Channel Service Unit/Digital Service Unit. A device that knows how to use the layer 1 details of telco Layer 1 serial links that connect to devices such as routers. |
| DTE | Data Terminal Equipment. The DTE synchronizes its clock based on the DCE clock. (Layer 1). Otherwise it is a device not within the service provider’s network (like a routher). |
| DS0 | Digital Signal Level 0. 64Kbps line from the telco. Used for single voice calls. |
| DS1 | Digital Signal Level 1. 1.544Mbps line inside a telco. Uses 24 DSO channels of its original speed plus a management/framing channel of 8Kbps. Also known as a T1. |
| Frame Relay | A standard data-link protocol to create frame-switched or packet-switched service that uses DTE devices (such as routers) to connect to other devices using one physical connection. |
| HDLC | High-level Data Link Control. Data-link layer protocol. |
| Packet Switching | Term used to reference services that examine the contents of data to make forwarding decisions. |
| T1 | 1.544Mbps line inside a telco. Uses 24 DSO channels of its original speed plus a management/framing channel of 8Kbps. Also known as DS1. |
| PDU | OSI Protocol Data Unit. This includes headers and trailers for the current layer and all the encapsulated data, if any. Often used as L#PDU. For example, L2PDU references the Data Link layer data unit. |