m:n-Translation, m,n>=1 and m=n
With static address translation we can translate between IP networks
that have the same size (contain the same number of IPs). A special
case is when both networks contain just one IP, i.e. the netmask is
255.255.255.255. This NAT strategy is easy to implement, since the
entire translation process can be written as one line containing a
few simple logic transformations:
new-address = new-network OR (old-address AND (NOT netmask))
In addition, no information about the state of connections that are being translated needs to be kept, looking at each IP packet individually is sufficient. Connections from outside the network to inside hosts are no problem, they just appear to have a different IP than on the inside, so static NAT is (almost) completely transparent.
Example: