Cisco Systems Cisco IOS XR Loading software images from a network server, such as Tftp, GL-7

MPLS TE

MSC

MTU

multicast

Glossary

Multiprotocol Label Switching traffic engineering. A switching method that forwards IP traffic using a label. This label instructs the routers and switches in the network where to forward the packets based on pre-established IP routing information.

modular services card. Module in which the ingress and egress packet processing and queueing functions are carried out in the Cisco CRS-1 architecture. Up to 16 MSCs are installed in a line card chassis; each MSC must have an associated physical line 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. See also PLIM.

MSCs are also referred to as line cards.

maximum transmission unit. Maximum packet size, in bytes, that a particular interface can handle.

Multicast is a feature that refers to single packets copied by the network and sent to a specific subset of network addresses. These addresses are specified in the Destination Address Field. See also unicast.

N

netboot	Loading software images from a network server, such as TFTP.
node	A card installed and running on the router.
NSF	nonstop forwarding. Packets keep flowing during events such as failover, process restarts, and the
	upgrade or downgrade of software packages. Nonstop forwarding is the ability of a router to continue
	to forward traffic toward a router that may be recovering from a transient failure and the ability of a
	router recovering from a transient failure in the control plane to continue correctly forwarding traffic
	sent to it by a peer.
NTP	Network Time Protocol. Protocol built on top of TCP that ensures accurate local time-keeping with
	reference to radio and atomic clocks located on the Internet. This protocol is capable of synchronizing
	distributed clocks within milliseconds over long time periods.
NVRAM	nonvolatile RAM. Static random access memory that is made into nonvolatile storage by having a
	battery permanently connected.

O

OC-x	Optical carrier, where x=3, 12, 48, or 192, relating to the various speeds within a SONET network.
OIR	online insertion and removal. Feature that permits the addition, replacement, or removal of cards
	without interrupting the system power, entering console commands, or causing other software or
	interfaces to shut down. Sometimes called hot-swapping or power-on servicing.

	Cisco IOS XR Getting Started Guide
OL-10957-02		GL-7