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ADSL2 and ADSL2+ Interfaces on NFX150 Devices

ADSL Interface Overview

Asymmetric digital subscriber line (ADSL) technology is part of the xDSL family of modem technologies that use existing twisted-pair telephone lines to transport high-bandwidth data. ADSL lines connect service provider networks and customer sites over the "last mile" of the network—the loop between the service provider and the customer site.

ADSL transmission is asymmetric because the downstream bandwidth is typically greater than the upstream bandwidth. The typical bandwidths of ADSL2 and ADSL2+ circuits are defined in Table 1.

Table 1: Standard Bandwidths of DSL Operating Modes

Operating Modes

Upstream

Downstream

ADSL2

1—1.5 Mbps

12—14 Mbps

ADSL2+

1—1.5 Mbps

24—25 Mbps

ADSL2 and ADSL2+ support the following standards:

  • LLCSNAP bridged 802.1q

  • VC MUX bridged

The ADSL Mini-PIM facilitates a maximum of 10 virtual circuits on supported security devices.

Supported security devices with Mini-PIMs can use PPP over Ethernet over ATM (PPPoEoA) and PPP over ATM (PPPoA) to connect through ADSL lines only.

ADSL2 and ADSL2+

The ADSL2 and ADSL2+ standards were adopted by the ITU in July 2002. ADSL2 improves the data rate and reach performance, diagnostics, standby mode, and interoperability of ADSL modems.

ADSL2+ doubles the possible downstream data bandwidth, enabling rates of 20 Mbps on telephone lines shorter than 5000 feet (1.5 km).

ADSL2 uses seamless rate adaptation (SRA) to change the data rate of a connection during operation with no interruptions or bit errors. The ADSL2 transceiver detects changes in channel conditions—for example, the failure of another transceiver in a multicarrier link—and sends a message to the transmitter to initiate a data rate change. The message includes data transmission parameters such as the number of bits modulated and the power on each channel. When the transmitter receives the information, it transitions to the new transmission rate.

Configuring ADSL SFP Interface Using VLANs on NFX150 Network Services Platform

Note:

Ensure that connectivity to the host is not lost during the configuration process.

To configure ADSL SFP interfaces on NFX150 devices:

  1. Connect to the host.
  2. Configure the WAN side front panel port with vlan-tagging.
  3. Configure a VLAN for the WAN side front panel port.
  4. Configure the WAN side front panel port with an IP address.
  5. Configure the physical (heth) interface with ADSL SFP options.
    Note:

    • The default value for encap is llcsnap-bridged-802.1q.

    • The ADSL SFP interface is enabled only if you configure vci and vpi. By default, vci and vpi are disabled.

  6. Map the physical (heth) interfaces to the virtual (ge) interfaces.
  7. Commit the configuration.

To verify the configuration, enter the show interfaces heth-0-4 command.

Configuring ADSL SFP Interface Without Using VLANs on NFX150 Network Services Platform

Note:

Ensure that connectivity to the host is not lost during the configuration process.

To configure ADSL SFP interfaces on NFX150 devices:

  1. Connect to the host.
  2. Configure the WAN side front panel port with an IP address.
  3. Configure the physical (heth) interface with ADSL SFP options.
    Note:

    • The default value for encap is llcsnap-bridged-802.1q.

    • The ADSL SFP interface is enabled only if you configure vci and vpi. By default, vci and vpi are disabled.

  4. Map the physical (heth) interfaces to the virtual (ge) interfaces.
  5. Commit the configuration.

To verify the configuration, enter the show interfaces heth-0-4 command.