Page 860 7750 SR OS Services Guide
Subscriber Interfaces
Subscriber interfaces are composed of a combination of two key technologies, subscriber inter-
faces and group interfaces. While the subscriber interface defines the subscriber subnets, the group
interfaces are responsible
for aggregating the SAPs.
• Subscriber interface — An interface that allows the sharing of a subnet among one or
many group interfaces in the routed CO model.
• Group interface — Aggregates multiple SAPs on the same port.
• Redundant interfaces — A special spoke-terminated Layer 3 interface. It is used in a
Layer 3 routed CO dual-homing configuration to shunt downstream (network to
subscriber) to the active node for a given subscriber.
IPv6 Enhanced Subscriber Management (ESM)
All IPv6 ESM services require either Routed CO (IES), or Routed CO for VPRN as a supporting
service construct. Because of the complexities of the IPv6 link-model, there is currently no support
for IPv6 ESM in a VPLS. There is also currently no support for IPv6 in combination with Basic
Subscriber Management (BSM).
RADIUS Accounting
In the 7750 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 OS
releases, it was possible to have many hosts sharing a common sla-profile instance, and thus
accounting and QoS parameters. Complications would arise 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.
Dual-stack subscribers are now two different hosts sharing a single sla-profile instance. A new
RADIUS accounting mode has been introduced to support multiple-host environments.
A new command, host-accounting, is introduced under accounting-policy, which allows
configurable behavior.
No host-accounting:
When no host-accounting is configured, accounting behavior is as follows:
• A RADIUS accounting start message is sent when the SLA-profile instance is created. It
contains accounting (octets/packets) and the Framed-Ip-Address of the host which caused
the sla-profile instance to be created.
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