Detecting loss of ADSL & switchover to 3G

Discussion in 'Broadband' started by Peter, Jul 17, 2013.

  1. That should work.
    The Natural Philosopher, Jul 18, 2013
    1. Advertisements

  2. Peter

    Dave Saville Guest

    Err - wasn't the 13th the day BT had all the fun and games? Lots of us
    ended up on BT "parking" IPs requiring a router restart to get the
    correct fixed one. Affected many ISPs.
    Dave Saville, Jul 18, 2013
    1. Advertisements

  3. Peter

    Peter Guest

    Yes, supposedly.

    I have a SMS controlled switch and tried power cycling the
    router+modem but it didn't do anything.

    Eventually it came back on.

    BUT the 3G backup ought to work in this case, or there should be some
    way to make it work, and that's what I am looking for.

    MAYBE I could have another SMS controlled relay which breaks the BT
    cable (until another SMS is used to re-connect it) so if BT have
    allocated a crap IP, I could force a 3G fallover that way. Hey - there
    is an idea :)

    Of course that assumes that A&A's 3G connectivity is actually working.
    If they use BT to connect their routers to the "3" network, it may not
    work. I asked them about this but could not get any comment.
    Peter, Jul 18, 2013
  4. Peter

    Mike Guest

    I think somewhere I saw an option to fix it, or let it be
    dynamically allocated, with the suggestion that dynamic
    was better "in case it needed to change, although it's rare
    it will". And I left it as dynamically set. The internal
    IP address I did lock as static.

    I suppose fixing the WAN side down shouldn't be too
    problematic. But then again, outages aren't that frequent.
    Then you're one up on me. I'll give it a go for next time ...
    Mike, Jul 18, 2013
  5. Peter

    Phil W Lee Guest

    You need to ping with a TTL of 2

    That will work through DSL (because it is the router that your DSL
    modem connects to, so is very close) but will fail over 3g (because it
    will have to go through the 3g providers network before it can even
    get to A&As network, never mind that particular router).

    So it will detect whether you have a valid dsl connection or not.
    If I recall correctly, the switch for ping to set a maximum TTL is -i
    TTL but I could be wrong.
    If I'm right, the command would be:
    ping -i 2
    or, to avoid relying on dns working correctly:
    ping -i 2
    Phil W Lee, Jul 18, 2013
  6. Peter

    Phil W Lee Guest

    Shame about the BT senior wetware :-(
    Phil W Lee, Jul 18, 2013
  7. Peter

    Jono Guest

    Graham J has brought this to us :
    Broadband backup

    You can specify a username and password for a DSL line and receive
    routing for the IP addresses for that line - this allows the Data SIM
    to be used in a 3G router to provide a backup for DSL lines with full
    legacy IP routing including blocks of IPs, and full 1500 byte MTU
    Jono, Jul 18, 2013
  8. Peter

    Justin C Guest

    I was just considering such a thing for our set up. Could you
    tell me what you are using, and if you think it is any good?

    Justin C, Jul 19, 2013
  9. Peter

    Peter Guest

    It is a GSW2 LITE.

    I don't recall where it came from; it was about £150.

    Google turns up e.g.

    The relay is a bit small and I wired it up to a big 20A external

    You send it a text message and it interrupts the power to the gear for
    ~ 3 seconds.

    The config is terrible (1970s VCR kind of level) and is done with text

    To stop the SIM expiring you config it to phone you every ~80 days.
    There is no option for a periodic SMS; only a voice call (so you get
    this silent call, which the box hangs up as soon as you answer the

    It works well though.

    You put in a PAYG SIM with say £20 on it and it will last for years.
    Peter, Jul 19, 2013
  10. Peter

    Jono Guest

    Jono, Jul 20, 2013
  11. Peter

    pcourtney1 Guest

    we use a lot of these, they work really well and only cost £63 inc vat and p&p

    does not use SMS, so no mobile sim to top up, but you call the phone numberthat the ADSL router is on and turn off the power until you call in again 1 minute later to turn the power back on, not perfect, but ideal for our needs, and when we need to reboot the switch, router or anything else that ison the same 4 way gang power bar at a remote site
    pcourtney1, Jan 11, 2015
  12. Peter

    Bob Eager Guest

    He's probably solved the problem in the last 18 months.

    But if he hasn't....
    I use a Draytek 2860 which does 3G fallback nicely.
    Bob Eager, Jan 11, 2015
    1. Advertisements

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.