Glossary
GL-3
Cisco IOS XR Getting Started Guide
OL-10957-02
DIMM dual in-line memory module. Small circuit boards carrying memory integrated circuits, with signal and
power pins on both sides of the board, in contrast to single-in-line memory modules (SIMMs).
disk0 Name of the flash disk on which the Cisco IOS XR software is stored.
disk1 Name of the optional flash disk on which the Cisco IOS XR software can be sto red in preparation for
installation or upgrade.
DNS Domain Name System. Mechanism used in the Internet and on private intranets for translating names
of host computers into addresses. The DNS also allows host computers not directly on the Internet to
have a registered name in the same style.
DPT Dynamic Packet Transport. DPT rings are dual, counter-rotating fiber rings. Both fibers are used
concurrently to transport both data and control traffic.
DSC designated shelf controller. The RP or RP pair that controls a standalone router or a multishelf system.
The DSC is selected from among the route processors (RPs) installed in the router or mul tishelf system.
E
eBGP external Border Gateway Protocol. BGP sessions are established between routers in different
autonomous systems. eBGPs communicate among different network doma ins.
ECC error correction code. ECC is used to correct errors within memories on the Cisco CRS-1 router.
egress Outgoing channel.
Ethernet Baseband LAN specification invented by Xerox Corporation and developed jointly by Xerox, Intel, and
Digital Equipment Corporation. Ethernet networks use CSMA/CD and r un over a variety of cable types
at 10 Mbps. Ethernet standards are defined by the IEEE 802.3 specification.
F
fabric Connectivity between all line cards. Also referred to as switch fabric.
fabric cable Fabric cables are optical array cables that interconnect the fabric components in each chassis of a Cisco
CRS-1 Carrier Routing System Multishelf System. Each fabric cable con tains 72 fiber-optic strands,
which are packaged as 6 ribbon cables with 12 fibers in each ribbon cable.
FC fan controller. Two fan controller cards are installed in every line card chassis as a redundant pair to
manage the fan assemblies; a BITS timing connector exists on the fan controller card.
FIB Forwarding Information Base. Database that stores information about switching of data pac kets. A FIB
is based on information in the Routing Information Base (RIB). It is the optimal set of selected routes
that are installed in the line cards for forwarding. See also RIB.
flooding Traffic-passing technique used by switches and bridges in which traffic received on an interface is sent
out all the interfaces of that device except the interface on which the information was originally
received.