Cisco-Seven [NAT Application]! The difference and characteristics of dynamic and static routing~~~

What is NAT?

• Full English name: 【network address translations】
• Network address translation: Leading corporate networksinternet
• After converting the internal private network address of the enterprise into a public network address, use the public network address to share the connection internetservice

Classification of IP addresses [Divided by purpose]

Divided into private network address and public network address

• Private network address: Class A 10.0.0.0----10.255.255.255 Default subnet mask/8=255.0.0.0
  Class B 172.16.0.0----172.16.255.255 Default subnet mask/16=255.255.0.0
  172.17.0.0----172.17.255.255
  172.18.0.0----172.18.255.255
  ------------------------------ -
  172.31.0.0----172.31.255.255
  Class B IP address has a total of 16 private network bits
  Class C 192.168.0.0-192.168.255.255 has a total of 256 private network bits
  Default subnet mask/24=255.255.255.0
• Supplement: Internet: Operators (ISP)-China Unicom, China Mobile, Telecom

NAT is divided into three categories:

Static NAT: one to one

Router(config)# ip nat inside source static 172.18.7.250 1.0.0.250
Source——Static——Intranet server address——Purchase address (public network address)

Dynamic NAT: many to many, many one to one

Port multiplexing NAT (referred to as PAT): (private network) many-to-one (public network)-the most cost-effective

Implementation process:

1. First define the external network (public network) interface

int  s1/0

config-if) ip nat outside
#external network

2. Redefine the intranet enterprise intranet interface

int  f0/0     

config-if)#ip nat inside

3. Convert the internal network pool to the external network pool (mapping relationship)

Router(config) ip nat inside source list1 interface s1/0 overload
#Internal source internal network list external network interface overload

4. Define the internal address pool

r1(config)#access-list 1 permit any

5. Note: Do the default outward: ip route 0.0.0.0 0.0.0.0 s1/0

When more than 2 routers in the intranet use the router protocol OSPF, the default route must be injected into the intranet in the reverse direction

6. Reverse injection default

Router(config)#router ospf 100
Router(config-router)#default-information originate

7. Verify the NAT command

Router# sh ip nat translations//View the NAT address translation process

The difference between dynamic and static routing

• Static route: manually configure the route to the target network
• Features: When the network topology or link status changes, the network administrator needs to manually modify the relevant static routing information in the routing table
• Dynamic routing: application protocol to complete network intercommunication routing: rip ospf
• Features: It can automatically learn the topology of the network and update the routing table. The disadvantage is that routing broadcast update information will occupy a lot of network bandwidth

Please see the detailed link

Detailed explanation of dynamic and static routing