Cisco Systems Cisco uBR10012 manual See also Critical alarm, Major alarm, and Minor alarm, GL-2

Glossary

A

AAL

ATM adaptation layer. Service-dependent sublayer of the data link layer. The AAL accepts data from different applications and presents it to the ATM layer in the form of 48-byte ATM payload segments. AALs consist of two sublayers:the convergence sublayer and the segmentation and reassembly sublayer. Four types of AAL recommended by the ITU-T are AAL1, AAL2, AAL3/4, and AAL5; the Cisco uBR10012 uses AAL5.

Access list	List kept by routers to control access to or from the router for a number of services. For example, access
	lists can be used to prevent packets with a certain IP address from leaving a particular interface on the
	router.
Add drop	See ADM.
Multiplexer
ADM	Add Drop Multiplexer. A multiplexer that allows a signal to be added into or dropped out of a SONET
	span. See also SONET.
Alarm	A status condition that shows that a module or port is experiencing an abnormal operating condition.
	See also Critical alarm, Major alarm, and Minor alarm.
Application-specific	See ASIC.
integrated circuit
APS	Automatic Protection Switching. A SONET switching mechanism that achieves network resiliency by
	automatically switching from a primary circuit to a secondary circuit. This switching process occurs if
	the primary circuit fails or if the error rate on the primary line exceeds a set threshold. The Cisco 10000
	ESR supports 1+1 APS, which provides permanent electrical bridging to the service and protection
	equipment, placed at both ends of the circuit.

ASIC

Asynchronous Transfer Mode

ATM

Application-specific integrated circuit. A chip that is built for a specific application.

See ATM.

Asynchronous Transfer Mode. International standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells. Fixed-length cells allow cell processing to occur in hardware, thereby reducing transit delays. ATM is designed to take advantage of high-speed transmission media such as E3, SONET, and T3.

Authentication	In security, the verification of the identity of a person or process.
Automatic	See APS.
protection
switching
Alarm	A status condition that shows that a module or port is experiencing an abnormal operating condition.
	See also Critical alarm, Major alarm, and Minor alarm.

	Cisco uBR10012 Universal Broadband Router Hardware Installation Guide
GL-2	OL-18259-01