The binding BR maintains an address binding table that
contains the binding between the CE's IPv6 address,
the allocated IPv4 address and restricted port-set.
port-set
psid-offset psid-len psid
Describes a set of Layer 4 port numbers.
This may be a simple port range, or use the Port Set
Identifier (PSID) algorithm to represent a range of transport
layer ports that will be used by a NAPT.