FarSync Drivers | ![]() |
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When the FarSync driver is loaded, additional tty devices are created in /dev, these devices are named in the form:
tty_hdlcX where X is the port number
The port numbers for any given card can be determined by using the following command:
[kevinc@dash kevinc]$ more /proc/farsync FarSync WAN Driver version 2.2.2 - Patch Level 00 - Build -b233 3 Cards found hdlc0-hdlc1: FarSync T2U IRQ10, 2 ports, State: Running hdlc2-hdlc2: FarSync DSL-S1 IRQ5, 1 ports, State: Running hdlc3-hdlc6: FarSync T4U IRQ9, 4 ports, State: Running Total number of ports = 7 Total number of async connects = 1 [kevinc@dash kevinc]$
This shows that there are three cards installed. The first card has two ports, so therefore it's tty devices will be called /dev/tty_hdlc0 and /dev/tty_hdlc1
There Linux PPP Daemon consists of some user applications and some Kernel modules. Therefore to be able to use it, you must be using a Kernel that has been built with Linux PPP Daemon support. Providing PPP Daemon support is the standard for all Kernels provided in a Distro, but if you are building your own Kernel, you should include the PPP support in the Kernel configuration and ensure that the applications have been installed. If they are not already present in your system, then you may find them in an RPM archive on your Linux Distribution CD's. If not then you can download the latest source from
If you need IPV6 support, then make sure that you have a version of the pppd that supports it.
There are many HowTo's to help get you you running with the PPP Daemon. We have provided example Options files and scripts to start and stop the Daemon. When the FarSync product has been installed these will be found in the /etc/ppp directory, as follows:
options.tty.hdlcX
ppp-on
ppp-off
There are many options to the Linux pppd command, and these are well documented on the pppd Man page. However, as pppd has most often been used with asynchronous devices, e.g dialup modems, the most critical option to use is the "sync" option if you are using the port in sync mode. This will tell the pppd that the device is a synchronous device and modifies the protocol accordingly. The example options.tty_hdlc0 file contains
sync persist
Some FarSync cards can support an async mode (e.g. T4E and T4Ue), so it would be possible for async ppp to be used on these ports. In this case the sync parameter would not be required. Use the farutil <device> command to find out if your ports have async capability.
In debugging your ISP connection you may wish to add the following parameters to the options.tty_hdlcX file
debug nodetach
This will then show a PPP decode of the protocol exchanges in the window in which you invoked the ppp-on script.
To support IPv6, the following options can be used:
+ipv6 | Creates a randomized 'link local' address i.e. beginning with FE80: If you wish to specify the local address then use one of the IPv6 options shown below. |
ipv6 ::1 | Sets the local 'link local' address to FE80:0000:0000:0000:0000:0000:0000:0001 or FE8::1. Note that you can only set the bottom 8 octets. |
ipv6 ::1,::2 | Sets the local and remote 'link local' addresses to FE8::1 and FE8::2 respectively. Note that the setting of the remote address does not currently work. |
noip | Stops IPv4 addresses from being created for the link. If noip isn't specified, then valid IPv4 addresses must be specified for the link to succeed. |
To start a pppd session on hdlc0 port, for example, you should first edit the /etc/ppp-on script and select the correct operational parameters. Please note that the script sets the parameters in slightly different ways depending on if the port is an SHDSL or normal Farsync port. For SHDSL ports you will need to modify the following line:
/sbin/farutil $1 set media shdsl datarate 2304000 termtype remote annex b backoff 6 vpi 8 vci 35
Normal FarSync port parameters are set with the following command
/sbin/farutil $1 set media x21 clock 64000
When you have set the required parameters you can then invoke the script with the following command
/etc/ppp/ppp-on hdlc0
To stop a pppd session you should use the /etc/ppp/ppp-off script. This is particularly required if you are using an SHDSL port. The script is invoked as follows:
/etc/ppp/ppp-off hdlc0
The supplied scripts and options files should be used as templates and customised as required. If you are operating several pppd sessions that all have different operational parameters then you may need several ppp-on/ppp-off scripts.
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