Cisco CRS-1 - Carrier Routing System Router Getting Started Guide

Glossary
GL-8
Cisco CRS-1 Series Carrier Routing System Getting Started Guide
K
keepalive interval
Period of time between each keepalive message sent by a network device.
keepalive message
Message sent by one network device to inform another network device that the virtual circuit between
the two is still active.
L
LAIS
line alarm indication signal. Signal sent downstream indicating an upstream failure has occurred. LAIS
prevents the generation of unnecessary downstream failures being declared or alarms being raised.
Layer 2
Layer 2 refers to the data link layer of the commonly referenced multi layered communication model,
Open Systems Interconnection (OSI). The data link layer contains the address inspected by a bridge or
switch. Layer 2 processing is faster than layer 3 processing, because less analysis of the packet is
required.
Layer 3
Layer 3 refers to the network layer of the commonly referenced multi layered communication model,
Open Systems Interconnection (OSI). The network layer is concerned with knowing the address of the
neighboring nodes in the network, selecting routes and quality of service, and recognizing and
forwarding to the transport layer incoming messages for local host domains.
A router is a Layer 3 device, although some newer switches also perform Layer 3 functions. The
Internet Protocol (IP) address is a Layer 3 address.
LC
line card. Line cards in the Cisco CRS-1 Series system are referred to as modular services cards
(MSCs). See modular services card.
LCIC
line card interface card. Internal fiber connections from a line card chassis are terminated at an LCIC
in the central fabric racks.
LDP
label distribution protocol. A standard protocol between MPLS-enabled routers to negotiate the labels
(addresses) used to forward packets. The Cisco proprietary version of this protocol is the Tag Distribution
Protocol (TDP).
LIB
Label Information Base. The table that contains the labels in use on the node.
lineup
A list of component versions. A lineup may be associated with a package, an SMU, or a project.
loopback
Send the outgoing signals back to the receiving side for testing purposes.
LOP
loss of pointer. Failure state in the SONET signal where a receiving network cannot identify or lock on
the pointer value of the H1 and H2 bytes to show the location of synchronous payload envelope (SPE).
LR
logical router. A collection of line cards and Route Processors that form a complete router. Each router
contains its own instance of dynamic routing, IP stack, system database, interface manager, and event
notification system.

Cisco CRS-1 - Carrier Routing System Router Specifications

General

Brand	Cisco
Model	CRS-1 - Carrier Routing System Router
Category	Network Router
Language	English