Configuring CoS for L2TP Tunnels on Ethernet Interfaces
The Layer 2 Tunneling Protocol (L2TP) is often used to carry traffic securely between an L2TP Network Server (LNS) to an L2TP Access Concentrator (LAC). CoS is supported for L2TP session traffic to a LAC on platforms configured as an LNS.
This feature has the following limitations:
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Sessions in excess of the maximum supported values specified for the PICs cannot be shaped (but they can be policed).
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There is no support for PPP multilinks.
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The overall traffic rate cannot exceed the L2TP traffic rate, or else random drops result.
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There is no support for logical interface scheduling and shaping at the ingress because all schedulers are now reserved for L2TP.
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There is no support for physical interface rate shaping at the ingress.
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You cannot delete or deactivate the primary Ethernet interface on which the tunnel is established.
You can provide policing support for sessions with more than the maximum supported value on each IQ2 or IQ2E PIC. Each session can have four or eight different classes of traffic (queues). Each class needs its own policer; for example, one for voice and one for data traffic.
To configure CoS for L2TP on Ethernet interfaces:
Configure L2TP services on the Ethernet interface.
On the Ethernet interface, enable session-aware CoS for L2TP sessions.
[[edit interfaces interface-name unit logical-unit-number] user@host# set per-session-scheduler
Configure the traffic manager in the PIC to enable per-session CoS support.
[edit chassis fpc slot-number pic pic-number] user@host# set traffic-manager mode-session-shaping
(Optional) To fine tune the system, you may also set the traffic-manager mode to session-shaping and configure the value of ingress-shaping-overhead parameter from 50 through 130 depending on your network requirement.
[edit chassis fpc slot-number pic pic-number] user@host# set traffic-manager ingress-shaping-overhead value mode-session-shaping
If you deactivate or delete the primary Ethernet interface on which the L2TP tunnel is configured, the tunnel with sessions having CoS is torn down.
After CoS is configured on an L2TP tunnel, Junos OS dynamically creates a traffic shaper for the traffic-shaping-profile and the L2TP tunnel based on the tunnel identification number. This ensures that the packets are monitored at the LAC and classified to allow the traffic flow to be adjusted on congested networks.
After CoS is enabled for L2TP tunnels on Ethernet interface, you can run the show class-of-service l2tp-session command to verify the mapping of CoS with the configured L2TP session.