Hi All,

I might have discovered a fix for "ADSL Tunnel Collapse".

Note that it is primarily theory, with a little empirical experience thrown in there ie. it 
worked for me when I had "ADSL Tunnel Collapse" symptoms :

1) If you try to create too many PPPoE sessions within a certain time period with an (or in 
Australia's case - Telstra's) ADSL Access Concentrator, it would appear to block your ethernet MAC 
address. This is probably to prevent (ok, I'll abuse the term) "hackers" from launching Denial 
Of Service attacks on the Access Concentrator. This is a reasonable tactic, this is the Internet remember.

**** NOTICE: if you are evil, and trying to DOS the Access Concentrator, then you are NOT TO READ 
ANY FURTHER. The information that follows is intended only for legitimate ADSL users who ONLY WISH to 
LEGITIMATELY REMEDY ADSL "tunnel collapse" access problems they are having with their ADSL service. 
The INFORMATION that follows is NOT TO BE ABUSED for nefarious purposes ****

2) For this type of DOS protection, there is typically a timer associated with the MAC address block. 
I don't know what it is, its probably something like 2 or more hours.

3) Every time you attempt to create another PPPoE session from that MAC address, you reset the 
block expiry timer, extending the time that your MAC address will be blocked. *** Therefore, the 
actions you (as a user) would typically take to try to fix this problem - attempting to persistently 
re-authenticate - _ actually make the problem worse _ ***

4) When it blocks your ethernet MAC address, you get a fault known commonly by help desk people as a 
"tunnel collapse". The common solution seems to be to get telstra to reset your line, which typically 
takes a few days.

So how do you get around this problem ? Simple. Change the MAC address you are using to contact the 
Access Concentrator.

There are basically two ways this can be done :

1) The non-OS specific method (forgetting for the moment you might need to change network card drivers) - 
temporarily use a different ethernet network card for ADSL access. Either have two cards in your machine, 
and patch it over, or perform a physical network card swap. Once you've changed network cards, try to 
log in again.

2) Some OS's support the temporary change of ethernet card MAC address. I use Linux, which allows you 
to change the MAC address of an ethernet card easily. Supposably some ethernet cards won't let you change 
their MAC address, I haven't come across any yet. Maybe really, really, really cheap ones won't 
(probably $2 is the cheapness threshold here).

I'm not going to specify how to change MAC addresses under Linux here, to avoid encouraging "hackers" 
who did not heed my notice above.

If you don't already know how to change MAC addresses under Linux, consider discovering how to be an 
adventure. Unix (and therefore Linux) has been called "the worlds best text adventure game". As a hint, 
there are two Linux utilities that can be used to do this, one old, one new. Try to avoid using google, 
you will learn much more that way.

HTH,
Mr Zippy.