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Cisco 10000 Series Router Quality of Service Configuration Guide
OL-7433-09
Chapter 17 Configuring Dynamic Subscriber Services
Shaping and Queuing Per-Session Traffic on LNS
In this simplified topology example:
1. Downstream traffic is forwarded from the ISP (the source) to an ISP subscriber (the destination)
during a PPP session.
2. From an LNS at the ISP, the traffic is transmitted over an L2TP tunnel to an L2TP Access
Concentrator (LAC) and then to the subscriber.
3. A user-defined offset size shapes and queues the per session traffic on an LNS. This offset applies
overhead bytes to outgoing traffic and the router uses the offset when calculating ATM overhead.
4. To specify the overhead offset in child and parent policies, use the bandwidth and shape
commands. The offset values and encapsulation types must match in the child and parent policies.
Feature History for Per Session Shaping and Queuing on LNS
Prerequisites for Per Session Shaping and Queuing on LNS
• Verify that the PPPoE (or PPPoA) sessions are enabled.
• Verify that L2TP resequencing is disabled.
• This feature uses policy maps in which queuing mechanisms (such as class-based weighted fair
queuing [CBWFQ]) are configured.
Restrictions and Limitations for Per Session Shaping and Queuing on LNS
• Cisco IOS Release 12.2(31)SB8 does not support load balancing when per session shaping and
queuing is configured. However, this release does support load balancing if no output QoS is applied
to the session. Cisco IOS Release 12.2(31)SB6 does not support load balancing at all on the LNS.
• Cisco IOS Release 12.2(31)SB10 supports load balancing for all QoS configurations, except those
containing a queuing action that is applied to a session. For example, the router does not support
load balancing for a session if the policy map applied to the session contains the shape, bandwidth,
or priority command.
• This feature does not support L2TP sequencing.
• This feature only applies when the LAC and LNS are connected by Ethernet.
Configuring Per Session Shaping and Queuing on LNS
To configure per session shaping and queuing over a L2TP LNS, perform the following configuration
task:
• Configuring a Per Session Shaping and Queuing on LNS Policy, page 17-46
Cisco IOS Release Description Required PRE
Release 12.2(31)SB6 The Per Session Shaping and Queuing on LNS feature was
introduced on the Cisco 10000 series router.
PRE3
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