Cisco Router Configuration: IP, VLAN, NAT, DNS, DHCP

ZA

Today we will be looking into the cisco router some common configurations like-ip, vlan, nat, dns and dhcp. These configurations will be shown into step by step.  


IP configuration

Router#enable
Router#conf terminal
Router(config)#interface gigabitEthernet 0/0
Router(config-if)#ip address 192.168.3.101 255.255.255.0 <any ip & SM>
Router(config-if)#no shutdown
Router(config-if)#exit

Loopback Interface Ip 

Router(config)#interface loopback 0
Router(config-if)#ip address <any IP>  <SM= /32 or 255.255.255.255>
Router(config-if)#exit



Vlan Configuration in Router

To configure the VLAN in router we have to configure the sub interface on the router physical interface.


Create and Configure Sub interface

Router#configure terminal 
Router(config)#interface gigabitEthernet 0/0.50 <any sub int. id>
Router(config-subif)#encapsulation dot1Q 50
Router(config-subif)#description pc0 <any name>
Router(config-subif)#ip address 20.0.0.1 255.255.255.0 <any ip & SM>
Router(config-subif)#no shutdown 

NAT Configuration

For NAT configuration we need to declare the outer and inner interface which they will respectfully be known as outside and inside NAT interface.

Router(config)#interface gigabitEthernet 0/0 <outer interface>
Router(config-if)#ip nat outside
Router(config-if)#exit

Router(config)#interface gigabitEthernet 1/0 <inner interface>
Router(config-if)#ip nat inside
Router(config-if)#exit

There are different types of NAT those will be discussing in this session.

Overloading or Port Address Translation (PAT)

Router(config)#access-list 1 permit 172.16.10.0 <src NW>   0.0.0.255 <wildcard addr>
Router(config)#access-list 1 permit 172.16.10.16    0.0.0.255
Router(config)#access-list 1 permit 172.16.10.32     0.0.0.15
Router(config)#ip nat inside source list 1 interface gigabitEthernet <outer interface> 0/0 overload


Static Port Address Translation (Port Redirection)

Router(config)# ip nat inside source static tcp 192.168.1.10  80<port no>  20.20.20.1   80<port no>



Configuring Static NAT 

Router(config)#ip nat inside source static 172.16.10.1<src ip addr> 172.16.0.2 <outer gw>(one-to-one nat)


Configuring Dynamic NAT 

Router#configure terminal
Router(config)#access-list 1 permit 10.0.0.10 0.0.0.0
Router(config)#access-list 1 permit 10.0.0.20 0.0.0.0
Router(config)#access-list 1 deny any
Router(config)#ip nat pool ccna 50.0.0.1 50.0.0.2 netmask 255.0.0.0
Router(config)#ip nat inside source list 1 pool ccna


To Show the NAT status

Router# show ip nat translations
Router# show ip nat statistics.



DNS Server Configuration

Router(config)#ip dns server
Router(config)#ip domain-lookup
Router(config)#ip name-server 8.8.8.8
Router(config)#ip host lab1 172.16.10.1  <host pc>
Router(config)#ip host lab2 172.16.0.1    <host pc>



DHCP Configuration

Router(config)#ip dhcp excluded-address 172.16.10.1 172.16.10.10 <any ip range>
Router(config)#ip dhcp pool VLAN-10
Router(dhcp-config)#network 172.16.10.0 255.255.255.0
Router(dhcp-config)#default-router 172.16.10.1
Router(dhcp-config)#dns-server 1.1.1.1
































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