The following restrictions apply to the integration of the ISG and an SCE:
When an SCE policy is deactivated, the policy is removed from the session on the SCE, and the session policy reverts to the
default SCE policy.
Only one SCE policy at a time may be applied to a session. Applying additional policies will override the policy previously
applied on the SCE.
This feature requires a control bus communication protocol, which runs over RADIUS and RADIUS extensions (as specified in
RFC 3576), operating in two modes; PUSH and PULL.
In PULL mode the ISG device waits for a query from the SCE.
In PUSH mode the download of an external feature is initiated by the ISG device as soon as an external service is activated
on the subscriber session.
To work with the SCE for subscriber management, the control bus protocol must do the following:
Support pushing a session and make relevant changes to a session to the SCE.
Allow a session, its relevant identity, and the SCE policy profile to be pulled from the ISG device by using an identity-based
Support accounting events, including the following:
Accepting SCE initiated accounting events asynchronously.
Correlating SCE accounting data to the appropriate ISG session.
Parsing the SCE accounting data to perform protocol translation.
The per-user IP subnet assigned to Point-to-Point Protocol (PPP) users during login is not communicated to SCE. A per-user
static route is downloaded to PPP users through the framed-route RADIUS attribute during login. ISG does not send the per-user
subnet address for a PPP session to SCE in the CoA provision session (ProvSess) attribute.