User's Manual

398
Users Manual of CS-6306R
 Translating inside source address
 Reloading inside global address
 Translating the overlapping address
 Providing TCP load balance
 Changing translation timeout time and limiting the number of connections
 Monitoring and maintaining NAT
43.2.3 NAT Configuration Task
43.2.3.1 Translating Inside Source Address
When the host communicates with the outside network, it uses the attribute (translating inside source address)
to translate its IP address to the unique global IP address. You can configure the static or dynamic inside
source address translation through the following method:
The static translation creates the one-to-one mapping between inside local address and inside global address.
When an inside host is accessed by a fixed outside address, the static translation is useful.
The dynamic translation creates the mapping between inside local address and outside address pool.
The following figure shows a routing switch translates the source address inside a network to the source
address outside the network.
Figure 43-1 NAT Inside Source Address Transfer
The following steps show the inside source address translation.
(1) The user of host 1.1.1.1 creates a connection between host 1.1.1.1 and host B.
(2) The first packet received by the routing switch from host 1.1.1.1 makes the routing switch check the NAT
table.
If a static translation item has been configured, the switch is to perform step 3.
If no translation exists, the switch decides that the source address (SA) 1.1.1.1 must be translated
dynamically, then chooses a legal global address from the dynamic address pool, and finally generates a
translation item. The type item is called as simple item.
(3) The routing switch replaces the inside local source address with the global address of the transfer item
and forwards the message.
(4) Host B receives the message through inside global IP destination address (DA) 2.2.2.2 and responds to
host 1.1.1.1.
(5) When the routing switch receives message of the inside global IP address, it takes the inside global