In the per session accounting mode of operation, an accounting message stream (START/INTERIM-UPDATE/STOP) is generated per session. An accounting message stream refers to a collection of accounting messages (START/INTERIM-UPDATE/STOP) sharing the same acct-session-id.
A PPPoE session is identified by the key {session-ID, mac}
An IPoE session is identified by the configured session-key: {sap, mac} | {sap, mac, Circuit-ID} | {sap, mac, Remote-ID}
For a single stack session, the behavior defined in the per session accounting model is indistinguishable from the per host accounting model. The per session accounting model makes difference in behavior only for dual-stack sessions.
The following are the properties of the Per Session Accounting model:
A single accounting session ID (acct-session-id) is generated per (IPoE or PPPoE) session and it can optionally be sent in RADIUS Access-Request message.
This acct-session-id is synchronized through MCS in dual homing environment.
The accounting messages (START, INTERIM-UPDATE, STOP) carry the acct-multi-session-id attribute denoting the queue instance (SLA profile instance) with which the session is associated.
The counters are collected from the queues and policers instantiated through the queue instance (SLA Profile Instance). If multiple sessions are sharing the same queue instance, the counters are aggregated. In other words, counters per individual session cannot be extracted from the aggregated count.
RADIUS-triggered changes and LI, targeted to the session’s accounting session ID are applicable per session:
In queue and policer RADIUS overrides, parameters for the referenced queue and policer within the session are changed accordingly.
Subscriber aggregate rate limits, scheduler rates, and arbiter rates are changed accordingly.
CoA DISCONNECT brings down the entire session.
LI activation based on the session acct-session-id affects the hosts within the session (dual-stack).
An SLA profile instance change affects all hosts (or sessions) sharing the same sla-profile instance (SPI). Queues are re-instantiated and counters are reset.
All applicable IP addresses (IPv4 and IPv6, including all IPv6 attributes; alc-ipv6-address, framed-ipv6-prefix, delegated-ipv6-prefix) are present in accounting messages for the session.