The format of IP-Port-Local-Id TLV is shown in Figure 14. This
attribute carries a string called "localID", which is a local
significant identifier as explained below.
The primary issue addressed by this TLV is that there are CGN
deployments that do not distinguish internal hosts by their internal
IP address alone but use further identifiers for unique subscriber
identification. For example, this is the case if a CGN supports
overlapping private or shared IP address spaces (as described in
and ) for internal hosts of different subscribers.
In such cases, different internal hosts are identified and mapped at
the CGN by their IP address and/or another identifier, for example,the identifier of a tunnel between the CGN and the subscriber. In
these scenarios (and similar ones), the internal IP address is not
sufficient to demultiplex connections from internal hosts. An
additional identifier needs to be present in the IP-Port-Range
Attribute and IP-Port-Forwarding-Mapping Attribute in order to
uniquely identify an internal host. The IP-Port-Local-Id TLV is used
to carry this identifier.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
| TLV-Type | Length | localID ....
Variable number of octets
String. The data type of this field is string (refer to
). This field contains the data that is a local
significant identifier at the customer premise, such as MAC
address, interface ID, VLAN ID, PPP sessions ID, VRF ID, IP
address/prefix, or another local significant identifier.
IP-Port-Local-Id TLV MAY be included in the following Attributes if
it is necessary to identify the subscriber:
o IP-Port-Range Attribute, identified as 241.6.11 (see)
o IP-Port-Forwarding-Mapping Attribute, identified as 241.7.11 (see)4. Applications, Use Cases, and ExamplesThis section describes some applications and use cases to illustrate
the use of the attributes proposed in this document.