Configuring the Method to Set the LAC Connection Speeds to the LNS
During the establishment of an L2TP tunnel session, the LAC sends L2TP (Tx) Connect Speed BPS AVP 24 to the LNS in Incoming-Call-Connected (ICCN) messages. AVP 24 conveys the transmit speed of the subscriber's access interface; that is, it represents the speed of the connection from the LAC to the LNS, from the perspective of the LAC. The L2TP Rx Connect Speed AVP 38 is included in the message when the RX speed is different from the TX speed. AVP 38 conveys the receive speed of the connection from the LNS to the LAC, again from the perspective of the LAC. When AVP 38 is not sent, it means that the connection speed is the same in both directions; the LNS uses the value in AVP 24 for both transmit and receive speeds.
You can configure what the LAC uses as a resource for setting these speeds. To use the recommended (advisory) downstream traffic shaping rate for AVP 24 and the recommended upstream shaping rate for AVP 38, include the tx-connect-speed-method advisory statement at the [edit services l2tp] hierarchy level. You configure the advisory rates under the PPPoE logical interface underlying the subscriber interface with the advisory-options statement at the [edit interfaces interface-name unit logical-unit-number] hierarchy level. When the advisory speed is not configured on the underlying interface, the tx-connect-speed-method advisory statement automatically sets the speed to 1 Gbps and sends this value in both AVP 24 and AVP 38.
Alternatively, to derive the speeds from the PPPoE IA tags, use the tx-connect-speed-method dsl-forum statement. In this case, AVP 24 is the value of Actual-Data-Rate-Downstream (VSA 26-129). AVP 38 is the value of Actual-Data-Rate-Upstream (26-130), and is sent only when the VSA values differ.
To set the method for calculating the transmit speed:
- Configure the advisory method to use the underlying interface’s
recommended shaping rates.[edit services l2tp]user@host# set tx-connect-speed-method advisory
- Configure the DSL Forum method to use the values provided
in the PPPoE IA tags.[edit services l2tp]user@host# set tx-connect-speed-method dsl-forum
