HPE FlexNetwork MSR Series Comware 7 Layer 3 - Ip Services Configuration Manuals page 151

Figure 60 NAT444 application diagram
Static NAT444
The NAT444 gateway computes a static NAT444 mapping before address translation. The mapping
is between a private IP address and a public IP address with a port block.
The NAT444 gateway uses private IP addresses, public IP addresses, a port range, and a port block
size to compute static mappings:
1. Divides the port range by the port block size to get the number of available port blocks for each
public IP address.
This value is the base number for mapping.
2. Sorts the port blocks in ascending order of the start port number in each block.
3. Sorts the private IP addresses and the public IP addresses separately in ascending order.
4. Maps the first base number of private IP addresses to the first public IP address and its port
blocks in ascending order.
For example, the number of available port blocks of each public IP address is m. The first m private
IP addresses are mapped to the first public IP address and the m port blocks in ascending order. The
next m private IP addresses are mapped to the second IP address and the m port blocks in
ascending order. The other static NAT444 mappings are created by analogy.
Dynamic NAT444
Dynamic NAT444 works as follows:
1. Creates a mapping from the internal host's private IP address to a public IP address and a port
block when the host initiates a connection to the public network.
2. Translates the private IP address to the public IP address, and the source ports to ports in the
selected port block for subsequent connections from the private IP address.
3. Withdraws the port block and deletes the dynamic NAT444 mapping when all connections from
the private IP address are disconnected.
Dynamic NAT444 uses ACLs to implement translation control. It processes only packets that match
an ACL permit rule.
Dynamic NAT444 supports port block extending. If the ports in the port block for a private address
are all occupied, dynamic NAT444 translates the source port to a port in an extended port block.
NAT444 gateway unified with BRAS device
The following matrix shows the feature and hardware compatibility:
Hardware
MSR954(JH296A/JH297A/JH298A/JH299A/JH373A)
MSR958(JH300A/JH301A)
NAT444 gateway and BRAS device
unification compatibility
No
No
137