- It is a layer-3 device.
- Stops broadcast by default/ doesnot forward broadcast across itself.
- Internetwork communication
- Path Selection
- Each port of a router is a broadcast domain.
- One port of a router= 1 broadcast domain= 1 network
Router components:
- ROM
Stores bootstrap and basic operating system software
- RAM
Volatile in nature
Loses content when power is down
Stores running configuration
- NVRAM
Non volatile RAM
Stores start up configuration
- Flash
Stores CISCO IOS
Can store multiple version of IOS
- Console
RS-232 protocol is used to connect through console
Doesnot require IP for communication
Is used for initial configuration or first time configuration of Cisco device.
- Interfaces
Supports multiple interface type
E.g. Ethernet, Fast Ethernet, GigaBit Ethernet, field fibre(GBIC/ SFP), serial interface(WIC-1T, WIC-2T, NM-4A/S, etc.)
Boot process of a router
- POST(Power On Self Test) Execute diagnostic from ROM on several hardware component
- Execute bootstrap after POST is successful
- Loads IOS from Flash. (if not , fall down from TFTP)
- Looks for valid configuration in NVRAM(NVRAM-> TFTP-> Console)
- If configuration is present, loads the configuration. If not, enters into set-up mode.
CISCO IOS mode
Hierarchial instruction each mode is to accomplish particular task
Each mode has specific set of commands,
1. User Exec mode
View only mode
Limited command
Syntax: Router >
2. Privilege Exec mode
File manipulation
Debugging and testing
Certain configuration command
Syntax: Router #
3. Global configuration mode
Entry to other specific configuration mode
Changes made in this mode affects the router globally
Syntax: Router (config) #
Interface configuration mode
Command related configure and interface
Router(config-if) #
Line configuration mode
Commands related to console and vty terminal
Router(config-line) #
Router> --User exec mode
Router> enable
Router#--Privilege exec mode
Router# configure terminal
Router (config) # ---- Global configuration mode
Setting host name
Router (config) # hostname RTR
RTR (config) #
Setting Clock
RTR (config) # exit
RTR # clock set hh:mm:ss <Day of month> <Month of the year> <Year>
Putting IP address on interface
RTR (config) # interface f0/0
RTR (config) # description ***Connected to LAN***
RTR (config) # IP address 192.168.1.1 255.255.255.0
RTR (config) #no shut down
RTR (config) # exit
Securing console
RTR (config) # line console 0
RTR (config-line) # password console 1
RTR (config-line) # login
RTR (config-line) # logging synchronous
RTR (config-line) # exit
Securing remote access
RTR (config) # line vty 0 4
RTR (config) # password telnet1
RTR (config) # login
RTR (config) # logging synchronous
RTR (config) # exit
Securing privilege exec mode
RTR (config) # enable password laba_ccna
OR
RTR (config) # enable secret laba_ccna1
Encrypting all future and current passwords
RTR (config) # service password- encryption
Banner
RTR (config) # banner motd # Unauthorized access is prohibited #
Enabling timestamp on debug and log message
RTR (config) # service timestamp debug date time msec
RTR (config) #service timestamp log date time msec
Saving configuration
RTR # copy running-config startup
OR
RTR # copy run start
OR
RTR # write memory
Erasing the configuration
RTR # write erase
RTR # reload -> reloading the router
Verify
RTR # show running config
RTR # show startup config
RTR # show clock
RTR # show flash
RTR # show version
RTR # show IP interface brief
RTR # show interface [interface number]
CDP(Cisco Discovery Protocol)
- It is a Cisco proprietary protocol
- Works at layer-2
- Used to find directly connected cisco devices
- Helpful in documenting network diagram
Verify:
RTR # show CDP neighbours
OR
RTR # show CDP neighbours detail
