networking basics and basic cisco commands
TRANSCRIPT
Networking Basics&
Basic CISCO Commands
IPv4 has 32 bit in decimal format
IPv6 has 128 bit hexadecimal format
IP Address Class:
Class A 0.0.0.0 to 127.255.255.255 (N.H.H.H), N=8 network bits, H=8 host bits
Class B 128.0.0.0 to 191.255.255.255 (N.N.H.H)
Class C 192.0.0.0 to 223.255.255.255 (N.N.N.H)
Class D 224.0.0.0 to 239.255.255.255 Reserved for Multicast Traffic
Class E 240.0.0.0 to 255.255.255.255 Reserved for R&D
The first IP of any class is network ID
The last IP is broadcast ID
Range of private IP
Class A 10.0.0.0 to 10.255.255.255
Class B 172.16.0.0 to 172.31.255.255
Class C 192.168.0.0 to 192.168.255.255
0.0.0.0 is not a valid address
127.0.0.0 is not a valid address (it is loopback address, used to ping hardware present)
Gateway address is address of the router
Important ports
Port 21 - ftp
Port 23 - telnet
Port 25 - smtp
Port 69 - tftp
Port 80 - http
Total ports: 0 to 65535
Reserved ports: 1 to 1023
Unreserved ports: 1024 to 65535
Router is a layer 2 (Network layer) device
Switch is layer 3 (Data link layer) device
Hub is layer 1 (Physical layer) device
Normally to communicate the two devices must be in same network
Physical layer transport data into bits form through medium (Cu cable, Fiber or wireless)
Datalink layer deals with hardware address
Network layer is responsible for transportation of data across different or multiple networks
Transport layer responsible for multiplexing, de-multiplexing, segmentation, sequencing, re-assembling, error correction & flow control
Session layer deals with establishing, maintaining & terminating the sessions/interactions
Presentation layer deals with encoding-decoding, encryption-decryption, compression-de compression
Application layer provides interface between user and application, port exist in this layer
DNS : Domain Name System
DHCP : Dynamic Host Control Protocol
ICMP : Internet Control Message Protocol
ARP : Address Resolution Protocol
RARP : Reverse Address Resolution Protocol
FLSM : Fixed Length Subnet Mask
VLSM : Variable Fixed Length Subnet Mask
NVRAM : Non Volatile RAM
OSPF : Open Shortest Path First
PAT : Port Address Translation
Subnetting is a method to divide large network into multiple small networks, done either by FLSM or VLSM depending on host requirement
The network ID of 192.168.1.1 is 192.168.1.0
To calculate wildcard mask subtract the subnet mask from 255.255.255.255
Eg. Calculate wildcard mask of 255.255.255.0
255. 255. 255. 255
255. 255. 255. 0
----------------------------------------------
0. 0. 0. 255 Required wildcard mask
Some basic commands
Router>show flash show flash details
Router>show version show version of ios
Router>show ip interface brief show interface details
Router>ping (ip) ping the ip for reachability
Router>traceroute (ip) trace path of given ip
Router>enable enters into privilege mode
Router#show running config
Router#show startup config
Router#copy (file with other details)
Router#erase (file with other details)
Router#configure terminal enters into global configuration mode
Router(config)#hostname (name) assign hostname
To save configuration
Router(config)#write
(or)
Router(config)#write memory
(or)
Router(config)#copy running-config startup-cnfig
Erase all configurations
Router(config)#erase startup-config
Router(config)#reload
Assigning password
Assigning console password
Router(config)#line con 0
Router(config)#password (password)
Router(config)#login
Router(config)#exit
Assigning auxiliary password
Router(config)#line aux 0
Router(config)#password (password)
Router(config)#login
Router(config)#exit
Assigning telnet password
Router(config)#line vty 04
Router(config)#password (password)
Router(config)#login
Router(config)#exit
Enable password
Router>enable
(password)
Router(config)#enable password (pasword)
(or)
Router(config)#enable secret (pasword)
