Virtual Circuit ID: VPI and VCI define a virtual circuit.

VPI: The valid range for the VPI is 0 to 255

VCI: The valid range for the VCI is 32 to 65535

ATM QoS Type: Select CBR to specify fixed (always-on) bandwidth for voice or data traffic. Select UBR for applications that are non-time sensitive, such as e-mail. Select VBR for burst traffic and bandwidth sharing with other applications. Cell Rate: Cell rate configuration often helps eliminate traffic congestion that slows transmission of real time data such as audio and video connections.

Peak Cell Rate: Divide the DSL line rate (bps) by 424 (the size of an ATM cell) to find the Peak Cell Rate (PCR).

Sustain Cell Rate: The Sustain Cell Rate (SCR) sets the average cell rate (long-term) that can be transmitted.

Maximum Burst Size: Maximum Burst Size (MBS) refers to the maximum number of cells that can be sent at the peak rate.

Login Information: PPPoA and PPPoE encapsulation only.

Service Name: Type the name of your PPPoE service here.

User Name: Enter the user name exactly as your ISP assigned.

Password: Enter the password provide by your ISP.

Connection: The schedule rules have priority over your Connection settings.

Nailed-Up Connection: Select Nailed-Up Connection when you want your connection up all the time.

Connect on Demand: Select Connect on Demand when you don't want the connection up all the time and specify an idle time-out in the Max Idle Timeout field.

Max Idle Timeout: Specify an idle time-out in the Max Idle Timeout field

TCP MSS Option: This will increase the current MSS limit to the number specified, hence the tweak test will report Max Packet Size as the specified number plus 40.

4.2.4 NAT

The NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a host in a packet. The default setting is Dynamic NAPT. It provides dynamic Network Address Translation capability between LAN and

37