In the ESM concept on network elements, a subscriber host is described by the following aspects:
subscriber-id-string
subscriber-profile-string
sla-profile-string
ancp-string
intermediate-destination-identifier-string
application-profile-string
This information is typically extracted from DHCP-ACK message using a Python script, and is used to provision subscriber-specific resources such as queues and filter entries. As an alternative to extracting this information from DHCP-ACK packet, provisioning from RADIUS server is supported.
As a part of this feature, the following VSAs have been defined:
alc-subscriber-id-string
Contains a string which is interpreted as a subscriber-id.
alc-subscriber-profile-string
Contains a string which is interpreted as a subscriber profile
alc-sla-profile-string
Contains string which is interpreted as an SLA profile.
alc-ancp-string
Contains string which is interpreted as an ANCP string.
alc-int-dest-id-string
Contains a string which is interpreted as an intermediate destination ID
alc-app-profile-string
Contains a string which is interpreted as an application profile
Note that these strings can be changed in a CoA request.
When RADIUS authentication response messages contain the above VSAs, the information is used during processing of DHCP-ACK message as an input for the configuration of subscriber-host parameters, such as QoS and filter entries.
If ESM is not enabled on a specified SAP, information in the VSAs is ignored.
If ESM is enabled and the RADIUS response does not include all ESM-related VSAs (an ANCP string is not considered as a part of ESM attributes), only the subscriber-id is mandatory (the other ESM-related VSAs are not included). The remaining ESM information (sub-profile, sla-profile) is extracted from DHCP-ACK message according to normal flow (Python script, and so on).
If the profiles are missing from RADIUS, they are not extracted from the DHCP data with Python to prevent inconsistent information. Instead, the data reverts to the configured default values.
However, if the above case, a missing subscriber ID causes the DHCP request to be dropped. The DHCP server is not queried in that case.
When no DHCP server is configured, DHCP-discover/request messages are discarded.