Cisco XR 12000 Series Getting Started Manual page 158

G
Gigabit Ethernet. Standard for a high-speed Ethernet, approved by the IEEE 802.3z standards committee
GE
in 1996.
Standard for a high-speed Ethernet, approved by the IEEE 802.3z standards committee in 1996.
Gigabit Ethernet
graphical user interface. A user environment that uses pictorial and textual representations of the input
GUI
and output of applications and the hierarchical or other data structure in which information is stored.
Such conventions as buttons, icons, and windows are typical, and many actions are performed using a
pointing device (such as a mouse). Microsoft Windows and the Apple Macintosh are prominent
examples of platforms using a GUI. See also CLI.
H
High availability is defined as the continuous operation of systems. For a system to be available, all
HA
components, including application and database servers, storage devices, and the end-to-end network,
need to provide continuous service.
high-level data link control. ISO communications protocol used in X.25 packet-switching networks.
HDLC
HDLC provides error correction at the data link layer and contains the following subsets: LAPB and
SDLC.
A number system having 16 as its base. This number representation uses the digits 0–9, with their usual
hexadecimal
meaning, plus the letters A–F (or a–f) to represent hexadecimal digits with values of (decimal) 10 to
15. The far right digit counts ones, the next counts multiples of 16, then 16^2 = 256, and so on.
Hexadecimal is more succinct than binary for representing bit masks, machines addresses, and other
low-level constants but it is still reasonably easy to split a hex number into different bit positions. For
example, the top 16 bits of a 32-bit word are the first four hex digits.
Passage of a data packet between two network nodes (for example, between two routers). See also hop
hop
count.
Routing metric used to measure the distance between a source and a destination.
hop count
Hypertext Transfer Protocol. Used by web browsers and web servers to transfer files, such as text and
HTTP
graphic files. 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.
I
Internet Control Message Protocol. Network layer Internet (TCP/IP) protocol that reports errors and
ICMP
provides other information relevant to IP packet processing.
IP explicit path. List of IP addresses, each representing a node or link in the explicit path.
IEP
Internet Engineering Task Force. Task force consisting of over 80 working groups responsible for
IETF
developing Internet standards. The IETF operates under the auspices of ISOC
Cisco IOS XR Getting Started Guide for the Cisco XR 12000 Series Router
GL-146
Chapter
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