NETWORKING

Branch routers

Category of routers that connect an organization's internal network to external networks or remote locations.

Integrated Services Routers (ISR)

Cisco router classification (such as the 800 and 900 series) designed to handle converged voice, video, and data traffic.

Primary traffic types optimized for Integrated Services Routers (ISR)

Voice and video traffic

Form factor

Term used to describe the physical size, shape, and structural design of a router chassis.

Physical capacity of the chassis

Hardware constraint that determines the maximum number of additional dedicated interfaces a router can accommodate.

Flash memory

Non-volatile storage location where the Cisco IOS operating system image is stored.

Terminal emulation program

Software category (such as PuTTY) used to establish a command-line interface session with a router.

Command to view router hardware specifications, IOS version, and device information

show version

RAM (Random Access Memory)

Volatile memory where the running operating system, running configuration file (running-config), and IP routing tables are stored.

Rack Unit (RU)

Standard unit of measurement for the height of a router chassis when mounted in an equipment rack.

Internetwork Operating System (IOS)

The core network operating system installed on Cisco routers and switches.

Privileged EXEC Mode

Primary Cisco IOS command mode (prompt Router#) providing full access to all device commands, monitoring tools, and configuration modes.

ROMMON (ROM Monitor)

Low-level bootstrap software environment available for diagnostics and password recovery when a valid IOS is unavailable.

Secure Shell (SSH)

Encrypted network protocol used for secure remote command-line access over a virtual interface.

Telnet

Unencrypted remote CLI access protocol that transmits management traffic in plain text.

User EXEC Mode

Basic Cisco IOS command mode (prompt Router>) that allows access to a limited set of non-disruptive monitoring commands.

Console port

Physical management port used for initial out-of-band device configuration and local CLI access.

Global Configuration Mode

Cisco IOS mode (prompt Router(config)#) used to modify settings that affect the entire device.

Command to move from User EXEC mode to Privileged EXEC mode

enable (shortcut: en)

Command to display a summary of router interfaces, operational status, and IP addresses

show ip interface brief

Command to check physical layer controller details and connected cable types for Serial 0/0/0

show controllers serial 0/0/0

Commands to enter and exit Global Configuration mode

configure terminal to enter, exit to leave

Shortcut key combination to return directly to Privileged EXEC mode

CTRL+Z

Command syntax to configure a Message of the Day banner

banner motd "<message>"

Command syntax to assign an IP address and subnet mask to a router interface

ip address <ip_address> <subnet_mask>

Command to set or update the device hostname

hostname <name>

Command to set an unencrypted password for Privileged EXEC mode access

enable password <password>

Command to enter configuration mode for the console management line

line con 0

Command to set an encrypted password for Privileged EXEC mode access

enable secret <password>

Command to view the active configuration file stored in RAM

show running-config

Command to encrypt all plain-text passwords stored in the system configuration file

service password-encryption

Command to view the IPv4 routing table in RAM

show ip route

Three main Cisco router categories

Branch, Network Edge, and Service Provider

NVRAM (Non-Volatile RAM)

Non-volatile memory location used to permanently retain the startup configuration file (startup-config) across reboots.