root/Documentation/isdn/syncPPP.FAQ

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simple isdn4linux PPP FAQ .. to be continued .. not 'debugged' 

Q: pppd,ipppd, syncPPP , asyncPPP .. what is that ?
  what should I use?
A: The pppd is for asynchronous PPP .. asynchronous means
here, the framing is character based. (e.g when
using ttyI* or tty* devices)

The ipppd handles PPP packets coming in HDLC
frames (bit based protocol) ... The PPP driver
in isdn4linux pushes all IP packets direct
to the network layer and all PPP protocol
frames to the /dev/ippp* device. 
So, the ipppd is a simple external network
protocol handler.

If you login into a remote machine using the
/dev/ttyI* devices and then enable PPP on the
remote terminal server -> use the 'old' pppd

If your remote side immediately starts to send
frames ... you probably connect to a 
syncPPP machine .. use the network device part
of isdn4linux with the 'syncppp' encapsulation
and make sure, that the ipppd is running and 
connected to at least one /dev/ippp*. Check the 
isdn4linux manual on how to configure a network device.

Q: when I start the ipppd .. I only get the
   error message "this systems lacks PPP support"
A: check that at least the device 'ippp0' exists.
   (you can check this e.g with the program 'ifconfig')
   The ipppd NEEDS this device under THIS name .. 
   If this device doesn't exists, use:
        isdnctrl addif ippp0
        isdnctrl encap ippp0 syncppp
        ... (see isdn4linux doc for more) ...
A: Maybe you have compiled the ipppd with another
   kernel source tree than the kernel you currently
   run ... 

Q: when I list the netdevices with ifconfig I see, that
   my ISDN interface has a HWaddr and IRQ=0 and Base 
   address = 0 
A: The device is a fake ethernet device .. ignore IRQ and baseaddr
   You need the HWaddr only for ethernet encapsulation.
   

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