CCNA 2 1 Flashcards
A WAN operates at the —– of the OSI reference model.
physical layer and the
data link layer
—- provide for the exchange of data packets
and frames between routers and switches and
the LANs they support.
WANs
HDLC
High Level Data Link Control
PPP
Point to point protocol
It describe how to
provide electrical, mechanical, operational, and
functional connections for WAN services
WAN physical layer protocols
It describe how frames are
carried between systems on a single data link.
WAN data link protocols
SDLC
Synchronous Data Link Control
CRC
Cycle Redundancy Check
ISDN
Integerated Service Digital Network
Typical WAN Layer 2 Links
Leased Line
Packet Switched
Circuit Switched
í Designed to carry IP packets
í Being replaced by PPP
SLIP
SLIP
í Serial Line Interface Protocol
í Support multiple network layer
protocols (IP, IPX, DecNET)
í Operates over sync. or async. links
PPP
PPP
í Point-to-Point Protocol
í IBM designed protocol
í Point-to-point & multipoint links
í Operates over sync. links
SDLC
SDLC
í Synchronous Data Link Control
Protocol
í IEEE standard from SDLC
í Point-to-point and multipoint links
í Operates over sync. links
- HDLC
í High-Level Data Link Control
HDLC
í High-Level Data Link Control
í used by X.25 protocol
LAPB
LAPB
í Link Access Procedure Balanced
í ISDN D-Channel for control signal
LAPD
í Link Access Procedure D-channel
í Used in Frame Relay for fast frame
switching over high-quality digital
facilities
LAPF
is a special type of
computer. It has a CPU, memory,
a system bus, and various
input/output interfaces.
A router
IOS
Internetwork
Operating System
It executes
instructions in the operating system. Among
these functions are system initialization, routing
functions, and network interface control.
The Central Processing Unit (CPU)
is a microprocessor. Large routers
may have multiple of this.
The CPU
it provides run time space for executable
Cisco IOS software and its subsystems.
RAM
— is usually logically divided into main
processor memory and shared input/output (I/O)
memory.
RAM
— can be upgraded by adding additional Dual
In-Line Memory Modules (DIMMs).
RAM
EEPROM
Electrically Erasable Programmable Read Only Memory
PCMCIA
Personal Computer Memory Card International Association
Holds the operating system image (IOS)
FLASH
It provides the necessary power
to operate the internal components.
The power supply
EIA/TIA
Electronic Industries Association and Telecommunications Industry Alliance)
