Analysis on the Implementation of NAT technology

Implementation of NAT technology-port multiplexing Dynamic Address Translation (PAT)

The IP address range used by the internal network is 10.100.100.1 ~ 10.100.100.254: the IP address of the LAN port of the router is 10.100.100.1, And the subnet mask is 255.255.255.0. The valid network IP address range is 11.11.11.0 ~ 11.11.11.3, the IP address in the WAN interface of the router is 11.11.11.1, The subnet mask is 255.255.255.252, And the IP address that can be used for conversion is 11.11.11.2. The internal website 10.100.100.1 ~ is required ~ 10.100.100.254 to the valid IP address 11.11.11.2.

Step 1: Set the external port.

 
 

  
  
interface serial 0  
  
  
 
  
  
ip address 11.11.11.1 255.255.255.252  
  
  
 
  
  
in nat outside 
 
 

Step 2: Set the internal port.

 
 

  
  
interface ethernet 0  
  
  
 
  
  
ip address 10.100.100.1 255.255.255.0  
  
  
 
  
  
ip nat inside 
 
 

Step 3: Define a valid IP address pool.

In nat pool ccxx 11.11.11.2 11.11.11.2 netmask 255.255.255.252

// Specify the Address Buffer Pool name as ccxx. Because PAT is used, only one public IP address is allowed in the address pool.

Step 4: Define the internal access columns.

Access-list 1 permit 10.100.100.0 0.0.255

The IP address range for Internetr access is 10.100.100.0 ~ 10.100.100.255, subnet mask:/24

Step 5: Set reuse of dynamic address translation.

In global setting mode, you can set up dynamic address conversion between the internal local address and the internal valid IP address. The command syntax is as follows:

Ip nat inside source list access list No. The pool's internal legal address pool name overload

Example:

Ip nat inside source list1 pool ccxx overload // convert the private ip address in access list 1 to the valid ip address defined in the onlyone ip address pool in Port multiplexing mode. The Overload keyword is the focus of this command.

For more information about NAT technology, see:

Implementation of NAT technology-static address translation

Implementation of NAT technology-Dynamic Address Translation

1. Principles of NAT technology
2. Analysis on the concept of vronat NAT
3. Analysis of multicast knowledge in IGMP V2 package
4. Horizontal split-by-the-command-by-product
5. Instance resolution: the floating summary routing configuration of the VPN gateway.
6. Analysis of multicast knowledge-Layer 2 device forwarding Multicast