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Configuring Dynamic CoS for an L2TP LAC Tunnel

Before you begin, configure the L2TP LAC. See Configuring an L2TP LAC.

In L2TP configurations, IP and L2TP headers are added to packets arriving at a PPP subscriber interface on the LAC before being tunneled to the L2TP network server (LNS).

Classifiers and rewrite rules enable you to properly transfer the ToS (Type of Service) value or the 802.1p value from the inner IP header to the outer IP header of the L2TP packet.

To manage the IP header values for a LAC tunnel:

  1. Configure the classifier for the inner tunnel.
    1. Define the fixed or behavior aggregate (BA) classifier.
      • To configure a fixed classifier:

      • To configure a BA classifier:

    2. Apply the classifier to the Layer 2 interface or Layer 3 interface. For Layer 2, you can apply the classifier at the PPP interface or an underlying VLAN interface. For Layer 3, you can apply classifiers to a family of PPP interfaces.
      • To apply the classifier for the IEEE 802.1p value:

      • To apply the classifier for the ToS value:

  2. Configure the rewrite rule for the egress tunnel.
    1. Configure the rewrite rule with the forwarding class and the loss priority value.
    2. Apply the rewrite rule to the PPP interface for which the L2TP tunnel is configured.
      • To apply the rewrite-rule for the IEEE 802.1p value:

      • To apply the rewrite rule for the ToS value: