Mobile L2TP Technical

From AAISP Support Site
Revision as of 09:27, 18 March 2015 by AA-Andrew (talk | contribs)

An L2TP tunnel is established using the pre-agreed IP addresses, hostname and shared secret. Note that if your LNS rejects the tunnel connection, or fails to respond to the SCCRQ or a subsequent HELLO, then it will be black listed for 5 minutes allowing further connections to go to the fall-back LNSs.

Once the tunnel is established, a session is established for each connecting data SIM.

ICRQ

Attribute Meaning
Assigned Session ID 14 Session ID
Call Serial Number 15 Present if received from mobile network
Calling Number 22 19 digit ICCID of SIM, starting 8944


Limitations

  • Only available on data SIMs.
  • Called Number is a fixed APN and not the one entered on the phone, which is ignored.
  • Reduced MTU of 1450 is in operation when L2TP is run over the internet. This restriction can be removed to allow full 1500 byte MTU where direct *Baby-jumbo frame links are available from us to your LNS.
  • User-Name passed is what is provided by the mobile which is usually blank. Do not use the password 'password' as this will not be passed through.
  • IPv6 is not available yet, but is planned for the future if possible.