Configuring the Method to Set the LAC Connection Speeds to the LNS
During the establishment of an L2TP tunnel session, the LAC sends the L2TP transmit connect speed in bits per second (BPS) using AVP 24 to the LNS in Incoming-Call-Connected (ICCN) messages. AVP 24 conveys the transmit connect 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 receive connect speed, which is represented by AVP 38, is included in the message when the receive connect speed is different from the transmit connect speed. AVP 38 conveys the receive connect 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 connect speeds.
You can configure what the LAC uses as a resource for setting these speeds. To use the recommended (advisory) downstream shaping rate for AVP 24 and the recommended upstream shaping rate for AVP 38, include the tx-connect-speed-method static 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.
To derive the speeds from the PPPoE IA tags, use the tx-connect-speed-method pppoe-ia-tags 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 (VSA 26-130), and is sent only when the VSA values differ.
To derive the speeds from the ANCP value configured on the PPPoE interface underlying the subscriber interface, use the tx-connect-speed-method ancp statement.
To set the method for calculating the transmit connect speed:
- Configure the ANCP method to use the values derived from
the configured ANCP value for the underlying interface. [edit services l2tp]user@host# set tx-connect-speed-method ancp
- Configure the PPPoE IA tags method to use the values provided
in the PPPoE IA tags.[edit services l2tp]user@host# set tx-connect-speed-method pppoe-ia-tags
- Configure the static (advisory downstream shaping rate)
method to use the underlying interface’s recommended shaping
rates.[edit services l2tp]user@host# set tx-connect-speed-method static
