CCNP Routing Study Guide- P17:T his book is intended to help you continue on your exciting new path toward obtaining your CCNP and CCIE certification. Before reading this book, it is important to have at least read the Sybex CCNA: Cisco Certified Network Associate Study Guide, Second Edition. You can take the CCNP tests in any order, but you should have passed the CCNA exam before pursuing your CCNP. | Glossary 449 cell payload scrambling The method by which an ATM switch maintains framing on some medium-speed edge and trunk interfaces T3 or E3 circuits . Cell payload scrambling rearranges the data portion of a cell to maintain the line synchronization with certain common bit patterns. cell relay A technology that uses small packets of fixed size known as cells. Their fixed length enables cells to be processed and switched in hardware at high speeds making this technology the foundation for ATM and other high-speed network protocols. See also cell. Centrex A local exchange carrier service providing local switching that resembles that of an on-site PBX. Centrex has no on-site switching capability. Therefore all customer connections return to the CO. See also CO. CER Cell Error Ratio In ATM the ratio of the number of transmitted cells having errors to the total number of cells sent in a transmission within a certain span of time. CGMP Cisco Group Management Protocol A proprietary protocol developed by Cisco. The router uses CGMP to send multicast membership commands to Catalyst switches. Challenge Used to provide authentication in Challenge Handshake Authentication Protocol CHAP as part of the handshake process. This numerically unique query is sent to authenticate the user without sending the password unencrypted across the wire. See also CHAP. channelized E1 Operating at an access link that is sectioned into 29 B channels and one D channel supporting DDR Frame Relay and . Compare with channelized T1. channelized T1 Operating at an access link that is sectioned into 23 B channels and one D channel of 64Kbps each where individual channels or groups of channels connect to various destinations supporting DDR Frame Relay and . Compare with channelized E1. CHAP Challenge Handshake Authentication Protocol Supported on lines using PPP encapsulation it is a security feature that identifies the remote end helping keep out unauthorized users. .
