Product specifications

Efficient Networks
®
Router family
Technical Reference Guide
Chapter 4: System Management
Efficient Networks
®
Page 4-25
Range Overlap Rules
• The per-interface commands, remote addhostmapping and eth ip
addhostmapping have these range overlap rules:
Private IP address ranges cannot overlap for an interface.
Public IP address ranges cannot overlap for an interface.
• The global command, system addhostmapping, has these range overlap
rules:
Private IP address ranges cannot overlap for a system.
Public IP address ranges cannot overlap for a system.
• If a private IP address range for an interface and a private IP address range
for the system overlap, the private IP address range for the interface has
precedence.
• If a public IP address range for an interface and the public IP address range
for the system overlap, the public IP address range for the interface has
precedence.
• Private IP addresses and public IP addresses can be the same.
For example, to enable IP/port translation to a remote router and make the IP
addresses 10.1.1.7 through 10.1.1.10 globally visible, it is permissible to use either
one of the following commands:
-> remote addhostmapping 10.1.1.7 10.1.1.10 10.1.1.7 remoteName
-> system addhostmapping 10.1.1.7 10.1.1.10 10.1.1.7
If the remapped host’s IP address (classic NAT, one-to-one IP address translation)
and the masquerading IP address (many-to-one IP address translation) are the same,
then NAT masquerading has precedence over classic NAT.
Selective NAT
A third implementation of performing NAT is called Selective NAT. In this method,
translation is performed on the basis of the destination address. Selective NAT
policies can be configured to specify the destination address and the public address
that the private addresses will need to be translated to, if translation is desired.
Creating Policies
The NAT policies define the NAT translation based on the destination address of the
outgoing packet. The policies contain the public address that the private addresses
will be translated to. Thus, if a selective NAT policy is found for the outgoing packet,
the private address on the packet will be translated to be public address specified in
the policy.
Selective NAT policies are created with two commands; one that will, based on the
destination address, translate the private address to a user-defined public address.