Experiment Environment:
company network topology as shown, the gateway router connected to three switches consisting of a core part of the company, in accordance with the vlan sectorization and connected to the respective departments through the switcher host
PC1 is vlan10 PC2 is vlan30 vlan20 PC3 to
three switches and The router address is 14.0.0.0 network segment
R4 router and R5 router is 45.0.0.0 network segment
L1. Set dhcp so that pc can automatically obtain an IP address. It is
required to convert company pc1 using static NAT to public network address and
pc2 and pc3 to use dynamic address conversion to public network address. Internet address to access the external network (internet) 
add vlan10, 20, 30 on sw2, sw3
Sw2 is assigned vlan10 and 
Sw3 is assigned vlan20, and 
Sw2 is used as trunk, 
Sw3 is used as trunk 
, and vlan10, 20, and 30 are assigned to 
Layer 3 switches. F1/14 -15 is used as trunk 
Setting Layer 3 switches F1/13 IP address 
setting R4 
Set the IP address of the two interfaces to the IP address of the R5 interface. 
Set the default route of L1 and R4 to make it communicate with each other. 
Do dhcp to make the pc automatically obtain an IP address. Then test the communication 
test to see if the pc can automatically obtain an IP address. 
Use pc1ping on R4 The
internal address of the 14.0.0.4 IP address can be communicated 
for NAT address translation. You can use pc to ping R5 (R5 IP address is the public network address)
to set NAT on R4, F0/0 is the inbound interface, and F0/1 is the outbound interface 
. Static address conversion 
settings pc2, pc3 IP address is dynamic conversion
definition internal network allows access to external network ACL 
In the global configuration mode, the internal local address specified by access-list is converted to the specified internal global address pool
(overload means using Address multiplexing)
Test using pc to access external address to surf the Internet
