JUNOS Enterprise Switching

Glossary

Author’s note: This is the same glossary we published in JUNOS Enterprise Routing, the companion volume to this book. We include it here for the reader focusing only on JUNOS switching and the EX platform.

3DES

Data Encryption Standard. Triple DES.

AAL

Asynchronous Transfer Mode (ATM) adaptation layer. A series of protocols enabling various types of traffic, including voice, data, image, and video, to run over an ATM network.

AAL5 mode

Asynchronous Transfer Mode (ATM) adaptation Layer 5. One of four ATM adaptation layers (AALs) recommended by the ITU-T. AAL5 is used predominantly for the transfer of classical IP over ATM. AAL5 is the least complex of the current AAL recommendations. It offers low-bandwidth overhead and simpler processing requirements in exchange for reduced bandwidth capacity and error-recovery capability. It is a Layer 2 circuit transport mode that allows you to send ATM cells between ATM2 IQ interfaces across a Layer 2 circuit-enabled network. You use Layer 2 circuit AAL5 transport mode to tunnel a stream of AAL5-encoded ATM segmentation and reassembly Protocol Data Units (SAR-PDUs) over a Multiprotocol Label Switching (MPLS) or IP backbone.

See Also cell-relay modeLayer 2 circuitsstandard AAL5 modetrunk mode

ABR

Area border router. Router that belongs to more than one area. Used in Open Shortest Path First (OSPF).

See Also OSPF

access concentrator

Router that acts as a server in a Point-to-Point Protocol over Ethernet (PPPoE) session—for example, an E Series ...