User Manual

Glossary
227
Glossary
H
HDLC High-level data link control. An International Telecommunication Union (ITU) standard for a
bit-oriented data link layer protocol on which most other bit-oriented protocols are based.
hold time Maximum number of seconds allowed to elapse between the time a BGP system receives
successive keepalive or update messages from a peer.
host subsystem Provides routing and system-management functions of the router. Consists of a Routing
Engine and an adjacent Control Board (CB).
I
IANA Internet Assigned Numbers Authority. Regulatory group that maintains all assigned and
registered Internet numbers, such as IP and multicast addresses. See also NIC.
ICMP Internet Control Message Protocol. Used in router discovery, ICMP allows router
advertisements that enable a host to discover addresses of operating routers on the subnet.
IDE Integrated Drive Electronics. Type of hard disk on the Routing Engine.
IEC International Electrotechnical Commission. See ISO.
IEEE Institute of Electronic and Electrical Engineers. International professional society for
electrical engineers.
IETF Internet Engineering Task Force. International community of network designers, operators,
vendors, and researchers concerned with the evolution of the Internet architecture and the
smooth operation of the Internet.
IGMP Internet Group Membership Protocol. Used with multicast protocols to determine whether
group members are present.
IGP Interior gateway protocol, such as IS-IS, OSPF, and RIP.
import To install routes from the routing protocols into a routing table.
interface routes Routes that are in the routing table because an interface has been configured with an IP
address. Also called direct routes.
IP Internet Protocol. The protocol used for sending data from one point to another on the
Internet.
IS-IS Intermediate System-to-Intermediate System protocol. Link-state, interior gateway routing
protocol for IP networks that also uses the shortest-path first (SPF) algorithm to determine
routes.
ISO International Organization for Standardization. Worldwide federation of standards bodies
that promotes international standardization and publishes international agreements as
International Standards.
ISP Internet service provider. Company that provides access to the Internet and related services.
ITU International Telecommunications Union (formerly known as the CCITT). Group supported
by the United Nations that makes recommendations and coordinates the development of
telecommunications standards for the entire world.