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ADSL Interfaces

Learn about ADSL interfaces and how to configure the ADSL interfaces on security devices.

ADSL Overview

Asymmetric digital subscriber line (ADSL) technology is part of the xDSL family of modem technologies that uses existing twisted-pair telephone lines to transport high-bandwidth data.

Table 1: ADSL Interface Details

Interface Details

Description

Interface name

ADSL

Supported on

For information about platforms support, see hardware compatibility tool (HCT).

Interface type

  • at- represents ADSL2 interface.

ADSL/ADSL2/ADSL2+ use cases

  • Connects the loop between service provider networks and customer sites. ADSL Mini-PIM facilitates a maximum of 10 virtual circuits on supported security devices and can use PPPoE over ATM and PPP over ATM (PPPoA) to connect through ADSL lines only.

  • Modems work as a dual-purpose ADSL circuit and can accommodate lower-frequency voice traffic and higher-frequency data traffic.

  • Improves the data rate and reach performance, diagnostics, standby mode, and interoperability of ADSL modems. It doubles the possible downstream data bandwidth, enabling rates of 20 Mbps on telephone lines shorter than 5000 feet (1.5 km).

  • Uses Seamless Rate Adaptation (SRA) to change the data rate of a connection during operation with no interruptions or bit errors and the ADSL2 transceiver detects changes in channel conditions with data transmission parameters.

For information about ADSL2 hardware specifications, see 1-Port ADSL2+ Mini-Physical Interface Module Network Interface Specifications.

Features Supported on the ADSL and ADSL2 Interfaces

Use Feature Explorer to confirm platform and release support for specific features.

Table 2: Key Features Supported on ADSL2

Feature

Description

ADSL Features

DSL

  • Supports ATM-over-ADSL interfaces.

  • Uses PPPoE ATM and PPP over ATM (PPPoA) to connect through ADSL lines only for supported security devices with Mini-PIMs.

ATM CoS Support

Ability of a network to guarantee CoS depends on the way in which the source generates cells and on the availability of network resources. Based on the way in which the source generates cells and the availability of network resources, the set of traffic descriptors specified are:

  • Peak cell rate (PCR)—Top rate at which traffic can burst.

  • Sustained cell rate (SCR)—Normal traffic rate averaged over time.

  • Maximum burst size (MBS)—MBS that can be sent at the peak rate.

  • Cell delay variation (CDV) tolerance—Allows you to delay the traffic for a particular time duration in microseconds to follow a rhythmic pattern.

Encapsulation

Enable an existing Junos OS CLI to support MLPPP encapsulation and the family mlppp.

To establish an ADSL link:

  • Use an RJ-11 cable to connect the CPE to a DSLAM patch panel. This forms an ADSL link.

  • Use OC3 or DS3 to connect the DSLAM to M Series or E Series devices to form an ATM backbone.

For more information about supported features and profiles on ADSL2 interfaces, see 1-Port ADSL2+ Mini-Physical Interface Module Key Features.

ADSL transmission is asymmetric because the downstream bandwidth is typically greater than the upstream bandwidth.

Table 3: Standard Bandwidths of DSL Operating Modes

Operating Modes

Upstream

Downstream

ADSL

800 Kbps—1 Mbps

8 Mbps

ADSL2

1—1.5 Mbps

12—14 Mbps

ADSL2+

1—1.5 Mbps

24—25 Mbps

ADSL2+ Annex M

2.5—3 Mbps

25 Mbps

Example: Configure ADSL Network Interfaces

In this example, configure the ADSL interface on an SRX firewall which supports LFI through an MLPPP. To support MLPPP encapsulation and the family mlppp on the ADSL interface on an SRX Series Firewall, you enable an existing Junos OS CLI. To establish an ADSL link between network devices, you must use some intermediate connections. First, use an RJ-11 cable to connect the CPE (for example, an SRX Series Firewall) to a DSLAM patch panel to form an ADSL link. Then use OC3 or DS3 to connect the DSLAM to M Series or E Series devices to form an ATM backbone.

Table 4: CLI Quick Configuration

Configuration Step

CLI Quick Configuration Commands

Configure the DHCP client on ADSL interface

 
set interfaces at-1/0/0 encapsulation ethernet-over-atm 
set interfaces at-1/0/0 atm-options vpi 2 
set interfaces at-1/0/0 dsl-options operating-mode auto 
set interfaces at-1/0/0 unit 0 
set interfaces at-1/0/0 unit 0 encapsulation ether-over-atm-llc 
set interfaces at-1/0/0 unit 0 vci 2.122 
set interfaces at-1/0/0 unit 0 family inet 
set interfaces at-1/0/0 unit 0 family inet dhcp

Configure the IPv6 address on an ADSL interface

 
set interfaces at-1/0/0 encapsulation ethernet-over-atm 
set interfaces at-1/0/0 atm-options vpi 2 
set interfaces at-1/0/0 unit 0 encapsulation ether-over-atm-llc 
set interfaces at-1/0/0 unit 0 vci 2.118
set interfaces at-1/0/0 unit 0 family inet6 address 13:13::1/64

Configure ATM-over-ADSL network interfaces

 
set interfaces at-2/0/0 atm-options vpi 25 oam-liveness up-count 200 down-count 200
set interfaces at-2/0/0 atm-options vpi 25 oam-period 100 
set interfaces at-1/0/0 unit 0 shaping cbr 
set interfaces at-1/0/0 unit 0 shaping vbr peak 33000 
set interfaces at-1/0/0 dsl-options operating-mode auto 
set interfaces at-1/0/0 encapsulation ethernet-over-atm 
set interfaces at-1/0/0 unit 3  encapsulation atm-nlpid oam-liveness up-count 200 down-count 200 
set interfaces at-1/0/0 unit 3 oam-period 100 
set interfaces at-1/0/0 unit 3 family inet 
set interfaces at-1/0/0 unit 3 vci 35

Configure CHAP on DSL interfaces

 
set access profile A-ppp-client client client1 chap-secret my-secret
set interfaces at-3/0/0 unit 0 ppp-options chap access-profile A-ppp-client local-name A-at-3/0/0.0 passive

Configure the DHCP client on ADSL interface

In this example, you configure the ATM interface as at-1/0/0. Then set the logical interface to unit 0 and specify the family protocol type as inet. Finally, configure the DHCP client. To configure DHCP client on ADSL interfaces:

  1. Set the encapsulation mode.
  2. Configure the ATM VPI option.
  3. Set operating mode.
  4. Set the logical interface.
  5. Set the encapsulation mode for logical interface.
  6. Set the ATM VCI option.
  7. Specify the family protocol type.
  8. Configure the DHCP client.
  9. Set the DHCP client identifier as an ASCII or hexadecimal value (optional):

    Use hexadecimal if the client identifier is a MAC address—for example, 00:0a:12:00:12:12.

  10. Set the DHCP lease time in seconds—for example, 86400 (24 hours). The range is 60 through 2147483647 seconds (optional).
  11. Define the number of attempts allowed to retransmit a DHCP packet (optional)—for example, 6

    The range is 0 through 6. The default is 4 times.

  12. Define the interval, in seconds, allowed between retransmission attempts (optional)—for example, 5.

    The range is 4 through 64. The default is 4 seconds.

  13. Set the IPv4 address of the preferred DHCP server (optional)—for example, 10.1.1.1.
  14. Set the vendor class ID for the DHCP client (optional)—for example, ether.

Use the show interfaces at-1/0/0 command to see the output of the configuration.

Configure the IPv6 Address on an ADSL Interface

To configure the IPv6 address on an ADSL interface:

  1. Configure the encapsulation type.

  2. Specify the annex type.

  3. Configure the encapsulation for the logical unit.

  4. Configure the VCI value.

  5. Configure family protocol type and assign an IPv6 address.

Use the show interfaces at-1/0/0 command to see the output of the configuration.

Configure ATM-over-ADSL Network Interfaces

This example shows how to use devices with ADSL Annex A or Annex B PIMs to send network traffic through a point-to-point connection to a DSLAM. Within the example, you set the DSL operating mode type to auto so that the ADSL interface will autonegotiate settings with the DSLAM.

The example shows how to create an ATM interface called at-2/0/0. The values for the interface’s physical properties are kept relatively low—

  • The ATM VPI is set to 25

  • Both the OAM down and up counts are 200 cells

  • The OAM period is set to 100 seconds

The example also shows how to set traffic shaping values on the ATM interface to support CoS. CBR is enabled in order to stabilize the cell transmission rate throughout the duration of the connection. Additionally, the VBR peak is set to 33,000 for data packet transfers.

Within the example, set the encapsulation mode to ethernet-over-atm to support PPP over Ethernet IPv4 traffic. Also configure a logical interface (unit 3). The logical interface uses ATM NLPID encapsulation. As with the physical interface, the OAM down count and up count are set to 200 cells on the logical interface. The OAM period is set to 100 seconds. The family protocol is set to inet, and the VCI is set to 35.

On SRX Series Firewalls, the ATM interface takes more than 5 minutes to boot when CPE is configured in ANSI-DMT mode and CO is configured in automode. This occurs only with ALU 7300 DSLAM, due to limitation in current firmware version running on the ADSL Mini-PIM.

To configure ATM-over-ADSL network interfaces for the devices:

  1. Create an ATM interface.

  2. Configure the physical properties for the ATM interface.

  3. Specify the CBR value and VBR value for the Ethernet interface.

  4. Set the DSL operating mode type.

  5. Configure the encapsulation type.

  6. Configure the encapsulation for the logical unit.

  7. Configure the OAM liveness values for an ATM virtual circuit.

  8. Specify the OAM period.

  9. Set the family protocol type.

  10. Configure the VCI value.

Use the show command to see the output of the configuration.

Configure MLPPP-over-ADSL Interfaces

In this example, you set the encapsulation as atm-mlppp-llc for the interface at-5/0/0. You then configure the family MLPPP bundle as lsq-0/0/0.1.

Figure 1 shows a typical example of MLPPP-over-ADSL end-to-end connectivity.

Figure 1: MLPPP-over-ADSL InterfaceADSL network architecture diagram showing data flow from J Series Device using VPI/VCI 8/80 through RJ-11, Patch Panel, DSLAM, ATM Backbone, OC3/DS3 to Remote Access Server with VPI/VCI 1/111.

To configure MLPPP on an ADSL interface:

  1. Configure an interface.

  2. Set the MLPPP encapsulation.

  3. Specify the family MLPPP.

  4. If you are done configuring the device, commit the configuration.

Use the show command to see the output of the configuration.

Configure CHAP on DSL Interfaces

In this example, specify the CHAP access profile and create an interface called at-3/0/0. Configure CHAP on the ATM-over-ADSL interface. Specify a unique profile name called A-ppp-client containing a client list and access parameters. Then specify a unique hostname called A-at-3/0/0.0 to be used in CHAP. Finally, set the passive option to handle incoming CHAP packets. To configure CHAP on the ATM-over-ADSL interface:

  1. Define a CHAP access profile.

  2. Create an interface.

  3. Configure CHAP and specify a unique profile name.

  4. Specify a unique hostname.

  5. Set the option to handle incoming CHAP packets only.

Use the show command to see the output of the configuration.

Verification

Display information about the parameters configured on the ADSL interfaces.

  • To verify that the DHCP options are configured use the run show system services dhcp client command:

    To verify the interface status and check traffic statistics use the show interface terse command and test end-to-end datapath connectivity by sending the ping packets to the remote end IP address:

  • To verify that the ADSL interface properties are configured use the show ipv6 neighbors command. The output shows a summary of interface information.

    The IPv6 Address field displays the configured IPv6 address on the interface.

  • To verify the ADSL interface properties, use the show interfaces at-1/0/0 extensive command:

    The output shows a summary of interface information.

    To verify the PPPoA configuration for an ATM-over-ADSL interface is correct, use the show interfaces at-1/0/0 and the show access commands.

  • To verify the configuration for an MLPPP-over-ADSL Interface is correct, use the show interfaces at-5/0/0 command.

  • To verify that the ADSL interface properties are enabled, use the show interfaces at-3/0/0 extensive command.

    To verify the PPPoA configuration for an ATM-over-ADSL interface is correct, use the show interfaces at-3/0/0 and the show access commands.

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