CoS for L2TP LNS Inline Services Overview
You can apply hierarchical scheduling and per-session shaping to Layer 2 Tunnel Protocol (L2TP) network server (LNS) inline services using a static or dynamic CoS configuration.
Guidelines for Applying CoS to the LNS
In L2TP configurations, IP, UDP, and L2TP headers are added to packets arriving at a PPP subscriber interface on the L2TP access concentrator (LAC) before being tunneled to the LNS.
When a service interface is configured for an L2TP LNS session, it has an inner IP header and an outer IP header. You can configure CoS for an LNS session that corresponds to the inner IP header only. The outer IP header is used for L2TP tunnel processing only.
However, we recommend that you configure classifiers and rewrite-rules to transfer the ToS (type of service) value from the inner IP header to the outer IP header of the L2TP packet.
Figure 1 shows the classifier and rewrite rules that you can configure on an LNS inline service.
By default, the shaping calculation on the service interface includes the L2TP encapsulation.