Cisco ASR 9000 Series Configuration Manual page 218

QoS Features Supported on BNG
Policy Inheritance
This table is relevant for egress direction only, as in ingress direction sub-rate policy and S-VLAN policy is
not supported:
Port
Sub-rate policy
Sub-rate policy
HQoS or policy with more than
class-default
No policy configured
Subscriber with No QoS
When QoS is not configured on a subscriber, the parent S-VLAN, or on the port, subscriber traffic goes out
using the default-queue of its parent's physical port.
• The subscriber is subjected to the S-VLAN policy and goes out using S-VLAN policy queues, if those
are present. If the S-VLAN policy does not have its own queues, then all the S-VLAN traffic, including
the subscriber's, goes out through the default queue of the physical interface.
• The subscriber is subject to a port policy, but no S-VLAN policy. Similar to the S-VLAN case, the
subscriber traffic is subject to it and uses its queues.
• If a non-port-shaper policy is applied on the port, the application of policy on S-VLAN and subscriber
is blocked. In such a scenario, subscriber traffic is subjected to the policy applied on the port.
Control Packet Handling
BNG provides priority treatment in handling PPP Link Control Protocol (LCP) packets. The control packets
are handled in high priority without the need of user configuration, and these packets are not subjected to QoS
policies that are applied on both ingress and egress of the interface. In the case of LAC upstream direction,
if user wants a trusted COS value, then a PPP command is provided to impose the core-side header based on
the set trusted-COS. Thus, this ensures the priority treatment of these control packets in the network.
Cisco ASR 9000 Series Aggregation Services Router Broadband Network Gateway Configuration Guide,
Release 4.3.x
206
S-VLAN
No policy is configured.
Inheritance limited to traffic getting
shaped by port sub-rate policy.
This is done irrespective of whether
a policy is configured on the
S-VLAN, or not.
Policy is configured. Inheritance
limited to traffic that gets shaped
by port sub-rate policy. This is
done irrespective of whether a
policy is configured on the
S-VLAN or not.
Policy configuration is blocked and
port policy is inherited.
Policy is configured.
Deploying the Quality of Service (QoS)
Subscriber
Subscriber policy , if present, is
executed first; then, traffic is
subjected to port-shaper.
Subscriber policy is executed first,
if present, and then, S-VLAN
policy is executed. Finally traffic
is subjected to port-shaper.
Policy configuration is blocked and
port policy inherited through the
S-VLAN.
Subscriber policy is executed first,
if present, and then S-VLAN policy
is executed.
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