FarSync Drivers

FarSync WAN Using the DSL-S1

Connecting the DSL-S1

The FarSync DSL-S1 card has an RJ11 connector for direct connection to your wall socket.  Data rates of between 192000 and 2304000 bits per second are supported, and are negotiated between the Customer Premises Equipment (CPE) and the network when the FarSync DSL-S1 port is opened.  Other operating parameters are also negotiated at the same time.  Opening the port is achieved by activating a network connection process, either a standard Generic HDLC PPP connection or by starting the Linux PPP Daemon for the port.  As most SHDSL Internet Service Providers offer connections over ATM, the Generic HDLC and PPP Daemon modes both run over ATM PVC connections.

Modes of Operation

The FarSync DSL-S1 can operate as either Central Office or Remote Office equipment.  When acting as Remote Office Equipment, it will respond to Embedded Operations commands over the Embedded Operations channel.  When acting as a Central Office Equipment, Embedded Operations Commands are not generated .  The mode of operation is a parameter that is specified when the port is opened.

If you are using FarSync DSL-S1 cards back to back in a private network then one of the DSL-S1 cards must be set to CENTRAL and the other REMOTE so that a DSL connection can be successfully negotiated.

If you are using the FarSync DSL-S1 card to connect to an ISP or other service through public exchange equipment then the setting should be REMOTE.

Annex A or Annex B

The physical two wire interface can be configured for USA (Annex A) or European (Annex B) modes of operation when the port is opened.

Other Parameter Recommendations

For normal operation the following recommendations are given for the SHDSL parameters.

DATARATE = 2304000   to obtain the fastest datarate possible
TERMTYPE = REMOTE    if connecting to an ISP.
TESTMODE = 0         No test loopback in place
BACKOFF  = 6         Suitable for most line types
VPI      = 5         Or whatever your ISP allocates to you
VCI      = 38        Or whatever your ISP allocates to you

Where to Set the Parameters

If you are using the Generic HDLC PPP procedures then you set the SHDSL parameters in the ifcfg-hdlcX configuration files.  These will be found in /etc/farsite/farsync.  To open the SHDSL port use the ifup hdlcX command, and to close it again use the ifdown hdlcX command.

If you are using the Linux PPP daemon, then you will find a ppp-on script in /etc/ppp.  Edit this script to set the parameters you require.  You will find them on a line that invokes the farutil command, which actually set the parameters.  More details in using the Linux PPP Daemon will be found here.

Showing the DSL Negotiation Process

A new utility has been introduced (fardsl) that can be used to show the DSL negotiation process.  Invoke it as follows:

fardsl <port>
e.g.
fardsl hdlc0

It will show output similar to that shown below:

  Tracking the Activation Status:
        Activation Status: Initialisation
        Activation Status: Processing CL
        Activation Status: Initialisation
        Activation Status: GHS Startup
        Activation Status: GHS Transaction Auto
        Activation Status: GHS Finished
        Activation Status: Transmit CR
        Activation Status: CRSR Silence
        Activation Status: Transmit SR
        Activation Status: Transmit TR
        Activation Status: Data

You can automatically invoke this utility from the ifup command by supplying an extra parameter show as follows:

ifup hdlc0 show

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