Auto-sub ID

The subscriber ID name (sub-id) is a mandatory object that binds all hosts of a specific subscriber together. Briefly, the sub-id name represents a residential household. Many management/troubleshooting and even billing operations rely on the sub-id name entity. The sub-id name is required for the host creation process, and it can be supplied by any authentication source, such as RADIUS, Diameter, LUDB, or Python. It can be derived from the sap-id or can be statically provisioned in the form of a string.

In some ESM deployments, it is desirable that the sub-id is automatically generated within the router instead of burdening the OSS with this function. A typical application for auto sub-id is as follows:

RADIUS server provides the SLA profile string and the sub-profile string but not the sub-id string.
The sub-id name is automatically generated and formatted based on the configured options.

The following are the properties of auto sub-id generation:

The automatic generation of the subscriber ID name can be based on any combination of the following fields:

MAC address
sap-id
circuit-id
remote-id
session-id

There can be only a single set of subscriber identification fields defined per host type (IPoE or PPPoE) per chassis. If the combination of the fields must be modified, the existing subscribers with an automatically generated subscriber ID must be manually terminated. Considering that remote termination of the IPoE subscribers by a DHCP server is not supported by all DHCP client vendors through the FORCERENEW DHCP message (RFC 3203, DHCP reconfigure extension), changing the subscriber fields while subscribers with automatically generated subscriber ID are active should be avoided.

The subscriber ID name automatic generation takes place at the end of the host initiation process (after the authentication phase is completed) and only in case whereby the subscriber ID had not been already provided by any other more specific means (RADIUS, Diameter, LUDB, or Python).

The format of the sub-id name can be either a 10-character encoded string (characters A to Z and 0 to 9) or a user- friendly string based on the subscriber identification fields. The maximum length of the subscriber ID name is 64 characters.

The subscriber ID name is not passed in the Access-Request to the RADIUS server because it is generated after the authentication phase.

The subscriber ID name can be automatically generated regardless of how the SLA or subscriber profile strings are obtained (RADIUS, LUDB, Python, or static).

The subscriber identification fields used in automatic generation of the subscriber ID name are enabled at the system level.

CLI syntax:

    configure
    subscriber-mgmt
        auto-sub-id-key 
            ppp-sub-id-key [mac] [sap-id] [circuit-id] [remote-id] [session-id]
            ipoe-sub-id-key [mac] [sap-id] [circuit-id] [remote-id] [dual-stack-remote-id]

If no sub-id-key per host type is configured, the defaults are:

Table: Defaults
PPPoE host type:	mac, sap-id, session-id
IPoE host type:	<mac, sap-id>.

The order in which the fields are configured is important because the subscriber ID name potentially becomes a concatenated string of the subscriber host identifiers in the order in which they are provisioned. The subscriber ID cannot be longer than 64 characters.

If the length of the concatenated fields for the subscriber ID name is longer than 64 characters, the host creation fails.
If the circuit ID or remote ID is in the key and they contain non-printable characters, their place in subscriber ID name are formatted in hex instead of ASCII. ASCII printable characters can contain the byte values 0x20 to 0x7E. All other values are ASCII non-printable and therefore, are formatted in hex characters.

The following would generate a subscriber ID name: xx:xx:xx:xx:xx:xx|1/1/3:23|44. The length of such subscriber ID name would be 29B.

mac: xx:xx:xx:xx:xx:xx
sap: 1/1/3:23
session-id: 44 (16bits length)

If the key contains the circuit ID as: 0x610163 (3 bytes), then the subscriber ID name is formatted as 610161, in hex, because 01 hex is non-printable in ASCII. Then the subscriber ID name’s length is 6B.

However, if the circuit ID is 0x616263 (3 bytes), then the string is formatted as ASCII string abc (three characters). The subscriber ID name’s length is 3B.

The assignment of the subscriber ID to dynamic hosts is performed in the following order:

From authentication sources: RADIUS, Diameter, LUDB, or Python.

A subscriber ID name obtained from authentication sources can conflict with the format of an implicit auto-generated subscriber ID name. When this happens, the subscriber host or session setup fails. Therefore, when implicit subscriber ID name generation is enabled (the default), a 10-character string containing the characters A to Z and 0 to 9 should not be returned from authentication sources. Information in Step 3 describes information to disable the implicit automatic generation of a subscriber ID name.
An explicit configured default is configured as def-sub-id:
- At the SAP level for static SAPs:
```
configure
   service ies/vprn
      subscriber-interface <ip-int-name>
         group-interface <ip-int-name>
            sap <sap-id>
               sub-sla-mgmt
                  def-sub-id use-sap-id | use-auto-id | string <sub-id>
```
- In the MSAP policy for managed SAPs:
```
configure
   subscriber-mgmt
      msap-policy <name>
         sub-sla-mgmt
            def-sub-id use-sap-id | use-auto-id | string <sub-id>
```
where:
- use-sap-id: the sub-id name is the SAP identifier
- use-auto-id: the sub-id name is a combination of the identifiers specified in auto-sub-id-key.
  
  The sub-id name is in a readable format, that is, a concatenation of the fields in the pppoe-sub-id-key or ipoe-sub-id-key command separated by a ‟|” character.
- string: the sub-id name is a user defined string
Implicitly generated default:

When no subscriber ID name is provided in authentication, and no explicit default is configured, then the system, by default, automatically generates a subscriber ID name, a 10-character string, using characters A to Z and 0 to 9, that is based on the fields defined in the:
- ppp-sub-id-key command for PPP host types. If no such fields are explicitly defined, the default are assumed: mac, sap-id, session-id.
- ipoe-sub-id-key command for IPoE host types. If no such fields are explicitly defined, the defaults are assumed: mac, sap-id.
The implicitly generated subscriber ID name is unique per chassis as well as in dual-homed environments.

The implicit automatic subscriber ID name generation can be disabled with the following command: configure subscr-mgmt auto-sub-id-key no implicit-generation.
- The implicit auto-sub-id name generation cannot be disabled when there are active subscribers in the system with an implicit automatically generated subscriber ID name.
- When disabled, the implicit auto-sub-id name generation cannot be enabled when there are active subscribers in the system.
With implicit subscriber ID generation disabled, the subscriber host or session setup fails when no subscriber ID name is provided in authentication, and no explicit default is configured. A 10-character subscriber ID name format, using the characters A to Z and 0 to 9, can be returned from authentication sources without risk of conflict.

Static subscribers are required to have the sub-id manually configured.