Roadmap for Configuring SCU with Layer 3 VPNs

SCU can be implemented over regular interfaces; it is also used in combination with Layer 3 VPNs. When you view SCU traffic on an ingress provider edge (PE) router, use the standard procedure outlined in Roadmap for Configuring SCU. However, when you enable packet counting for Layer 3 VPNs at the egress point of the MPLS tunnel, you need to take some additional steps, as follows:

1. Configure SCU on the virtual loopback tunnel (vt) interface of the egress PE router. See Configuring Input SCU on the vt Interface of the Egress PE Router.
2. Map the SCU-enabled input interface of that router to the virtual routing and forwarding (VRF) instance. See Mapping the SCU-Enabled vt Interface to the VRF Instance.
3. Configure SCU on the output interface of the egress router. See Configuring SCU on the Output Interface.
4. Configure an accounting profile and associate the source class with that accounting profile. You can also specify the filename for the data capture, a class usage profile name, and an interval indicating how often you want the SCU information to be saved. See Associating an Accounting Profile with SCU Classes.

Note: SCU over Layer 3 VPNs is not supported when the VRF table label is configured. Also, SCU is not supported over Layer 2 VPNs.

Related Topics

• Source Class Usage Solutions Page
• Overview of Source Class Usage
• System Requirements for SCU
• Example: SCU with Layer 3 VPNs Configuration

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