RADIUS session accounting with PD as a managed route

The Prefix Delegation (PD) prefix is included in the accounting messages using the VSA [99], Framed-IPv6-Route attribute with the string type ‟pd-host” appended to differentiate it from a regular framed IPv6 route; for example, FRAMED IPV6 ROUTE [99] 39 2001:1000::/64 :: 0 pref 0 type pd-host. PD as a managed route is applicable to both PPP and IPoE sessions and can point either to an IPv4 host or to an IPv6 WAN host.

Table: RADIUS accounting behavior describes the RADIUS accounting behavior based on the session type and the next-hop host.

Table: RADIUS accounting behavior
Session type and next-hop host RADIUS accounting start RADIUS accounting interims RADIUS accounting stop

PPP session with IPv6 PD pointing to IPv4 host as the next hop

A PPP connection triggers an accounting start

A DHCP NA+PD solicit triggers an interim update for the PD host with interim reason ‟delegated-ipv6-prefix-up” and the prefix included in the VSA Framed-IPv6-Route

A DHCP PD solicit triggers an interim update for the PD host with interim reason delegated-ipv6-prefix-up and the prefix included in the VSA framed-ipv6-route

Restriction:

A DHCP PD lease expire triggers an interim update with interim reason ‟delegated-ipv6-prefix-down”; however, the VSA framed-ipv6-route is not included

A PPP disconnect with only the IPv4 and IPv6 PD host triggers an accounting stop with the prefix included in the VSA Framed-IPv6-Route

Restriction:

A PPP disconnect with the IPv4, NA, and PD host without session-optimized-stop enabled, is not include the VSA Framed-IPv6-Route

PPP session with IPv6 PD pointing to IPv6 NA host as the next hop

A PPP connection triggers an accounting start. It is possible to have a single-stack IPv6-only session

A DHCP NA+PD solicit triggers an interim update for the PD host with interim reason delegated-ipv6-prefix-up and the prefix included in the VSA framed-ipv6-route

Restriction:

A DHCP PD lease expire triggers an interim update with interim reason ‟delegated-ipv6-prefix-down”; however, the VSA FramedIPv6-Route is not included

A PPP subscriber disconnect triggers an accounting stop with the PD host prefix included in the VSA Framed-IPv6-Route

IPoE session with IPv6 PD pointing to IPv4 host as the next hop

A DHCPv4 or a DHCPv6 request (DHCPv6 always performs NA and PD requests together) triggers the accounting start

A DHCP PD is always performed together with NA. The PD is not in the start message but is included in the accounting interim update as a part of the host update.

If the DHCPv4 lease expires, the interim update contains the PD prefix in the VSA framed-ipv6-route

Restriction:

A DHCP PD lease expire triggers an interim update with interim reason ‟delegated-ipv6-prefix-down”; however, the VSA Framed-IPv6-Route is not included

If only the IPv4 host and PD host remain, the release of the DHCPv4 triggers an accounting stop with the PD host prefix included in the VSA Framed-IPv6-Route

Restriction:

If the DHCPv4 is released and an IPv6 NA host remains, the IPv6 lease release/expire is an interim update that does not include the prefix

IPoE session with IPv6 PD pointing to IPv6 NA host as the next hop

A DHCPv4 or a DHCPv6 request (DHCPv6 always performs NA and PD requests together) triggers the accounting start. It is possible to have a single-stack IPv6-only session

A DHCP PD is always performed together with NA. The PD is not in the start message but is included in the accounting interim update as a part of the host update.

Restriction:

A DHCP PD lease expire triggers an interim update with interim reason ‟delegated-ipv6-prefix-down”; however, the VSA Framed-IPv6-Route is not included

If only the IPv6 subscriber is left, the release of NA contains the prefix of the PD host

Restriction:

If the DHCPv6 is released and an IPv4 host remains, the IPv6 lease release/expire is an interim update that does not include the prefix

RADIUS per host accounting:

In SR OS, the accounting paradigm is based on SLA profile instances yet this is at odds with traditional RADIUS authentication and accounting which is host-centric. In previous SR OS releases, it was possible to have many hosts sharing a common SLA profile instance, and therefore accounting and QoS parameters. Complications arose with RADIUS accounting because Accounting-Start and Accounting-Stop are a function of sla-profile instance and not the hosts. This meant that some host-specific parameters (like framed-ip-address) would not be consistently included in RADIUS accounting.

Currently, dual-stack subscribers are really two different hosts sharing a single sla-profile instance. A new RADIUS accounting mode has been introduced to support multiple-host environments.

Under accounting-policy, a host-accounting command allows configurable behavior.