Glossary

A
 
AAA
authentication, authorization, and accounting. A network security service that provides the primary framework to set up access control on a router or access server. AAA is an architectural framework and modular means of configuring three independent, but closely related security functions in a consistent manner.

B
 
BGP
Border Gateway Protocol. A routing protocol used between autonomous systems. It is the routing protocol that makes the Internet work. BGP is a distance vector routing protocol that carries connectivity information and an additional set of BGP attributes. These attributes allow for a rich set of policies for deciding the best route to reach a given destination.
Border Gateway Protocol
See BGP.

C
 
CLI
command-line interface.

E
 
eBGP
external Border Gateway Protocol. BGP sessions are established between routers in different autonomous systems. eBGPs communicate among different network domains.
EGP
Exterior Gateway Protocol. Internet protocol for exchanging routing information between different autonomous systems. EGP is an obsolete protocol that was replaced by BGP. See also BGP.
extensible markup language
See XML.

G
 
Gbps
Gigabits per second. The amount of data that can be sent in a fixed amount of time. 1 gigabit = 2 30 bits, 1,073,741,824 bits.

H
 
HTTP
Hypertext Transfer Protocol. Used by web browsers and web servers to transfer files, such as text and graphic files. The Hypertext Transfer Protocol (HTTP) is the set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. Relative to the TCP/IP suite of protocols (which are the basis for information exchange on the Internet), HTTP is an application protocol.
Hypertext Transfer Protocol
See HTTP.

I
 
IOS XR
The Cisco operating system used on the router.

L
 
line card
See modular services card. Line cards are now referred to as MSCs in the router.
LR
logical router. A routing system can be partitioned into several logical routers, each of which is managed independently. The terms router and LR are used interchangeably in this document.

M
 
modular services card
Module in which the ingress and egress packet processing and queueing functions are carried out in the router architecture. Up to 16 MSCs are installed in a line card chassis; each MSC must have an associated physical layer interface module (PLIM) (of which there are several types to provide a variety of physical interfaces). The MSC and PLIM mate together on the line card chassis midplane.
MSCs are also referred to as line cards.
MPLS-TE
Multiprotocol Label Switching traffic engineering.
MSC
See modular services card.

N
 
node
A card installed and running in a Cisco routing system. In the Cisco XR 12000 Series Router, nodes are identified by slot number (for example, node 1).

R
 
router
Network layer device that uses one or more routing metrics to determine the optimal path along which network traffic should be forwarded. Routers forward packets from one network to another based on network layer information.
running configuration
The router configuration in effect. Although, the user can save multiple versions of the router configuration for future reference, only one copy of the running configuration is in the router at any given time. An explicit commit operation must be performed to make changes to or update the running configuration on the router.

S
 
software configuration
A list of packages activated for a particular node. A software configuration consists of a boot package and additional feature packages.
SSH
Secure Shell.
SSL
Secure Socket Layer.
startup configuration
The router configuration designated to be applied on next router startup.
switchover
A switch between the active and standby cards; the old active card may be dead prior to switchover (death of the active card is one of the causes for the switchover). Also known as failover.
system reload
Reload of a Cisco router node.
system restart
Soft reset of a Cisco router node. This involves restarting all the processes running on that node.

T
 
TAC
Cisco Technical Assistance Center
target configuration
The current Cisco IOS XR running configuration plus the autonomous changes made to that configuration by a user. The target configuration is promoted to the running configuration by means of the commit command.
Tbps
Terabits per second = 1,000,000,000,000 (1 trillion) bits per second. The amount of data that can be sent in a fixed amount of time.
Telnet
Standard terminal emulation protocol in the TCP/IP protocol stack. Telnet is used for remote terminal connection, enabling users to log in to remote systems and use resources as if they were connected to a local system. Telnet is defined in RFC 854.
Terabyte
A unit of computer memory or data storage capacity equal to 1,024 gigabytes (2 40 bytes). Approximately 1 trillion bytes.

X
 
XML
extensible markup language. A standard maintained by the World Wide Web Consortium (W3C) that defines a syntax that lets you create markup languages to specify information structures. Information structures define the type of information (for example, subscriber name or address), not how the information looks (bold, italic, and so on). External processes can manipulate these information structures and publish them in a variety of formats. XML allows you to define your own customized markup language.
XML agent
A process on the router that is sent XML requests by XML clients and is responsible for carrying out the actions contained in the request and returning an XML response back to the client. The TTY-based XML agent is an example of an XML agent provided on the router.
XML client
An external application that sends an XML request to the router and receives XML responses to those requests.
XML operation
A portion of an XML request that specifies an operation that the XML client would like the XML agent to perform.
XML operation provider
The Cisco router code that carries out a particular XML operation including parsing the operation XML, performing the operation, and assembling the operation XML response.
XML request
An XML document sent to the router, containing a number of requested operations to be carried out.
XML response
The response to an XML request.
XML schema
An XML document specifying the structure and possible contents of XML elements that can be contained in an XML document.