Saturday, 12 November 2011
IPv6 on a cable modem?
So now, even on a cable modem, they have proper IPv4 and IPv6. Yes, as you may guess, it is our IPv4/6 via an L2TP tunnel and a FireBrick. I don't think any UK cable companies are doing IPv6 yet (tell me if I am wrong).
Obviously for a home installation a FireBrick is a tad overkill - I know that. We have plenty of geeky customers that love them even for home use, but they are typically used in small or even large businesses. They have a whole load of features, and one of the newest is operating as an L2TP client allowing a tunnel to be made to an L2TP server.
The L2TP server side (LNS) is in the "big brother" FB6202 model that we use as an ISP to handle broadband lines for customers, but the smaller versions do have support for L2TP as well, even if only for a few hundred connections. The latest addition means the FireBrick can connect in to our LNS just the same as a broadband line, but do it over another Internet connection (in this case a Virgin cable modem). It even works if the connection has NAT (NAT is evil).
Given that it took me about a day to get L2TP coded, I am quite pleased at how well it works (well, the L2TP was all in there, it basically needed the configuration to be a client). Of course, the best way to find any bits missing from the design (OK, "bugs" if you will) is to try it in anger, and that is what these crazy home installs are all about, even if it does mean putting up with James's driving to Richmond and back (it is OK, I have some motilium tablets for next time).
So, they ask me to fix their Internet and I make then a guinea pig, seems fair :-)
The advantage is that I get to try things that are a bit different - to try real life situations, like a cable modem!
We found the cable modem was a put fussy on the DHCP side, which was not a huge surprise, but not a problem. We then found there were several bits I needed to tweak on the L2TP side. Mostly it is changes to make things simpler and the configuration easier. So, all morning coding little bits of fine tuning and working well.
I wonder who's will be next. I am off to see my parents in a few weeks - perhaps they need a FireBrick install at home too :-)