Tuesday, February 08, 2011


IPv6 Part 1

It seems about time to start looking at and understanding IPv6 ahead of the inevitable transition. One of the ISPs resold by South Witham Broadband is Entanet and they are active in supporting IPv6 so I bit the bullet and bought a £10 Speedtouch 546v6 off Ebay to provide a bridged connection to my ADSL line.

The Speedtouch is used to provide a transparent bridge between the BT provided ADSL link to my router, in other words it acts as an ATM to ethernet bridge and allows the router to activate a PPPoE session and log in to Entanet. My router isn't IPv6 yet, but I can use a PC directly for starters. My initial objective was to get the bridge mode and PPPoE working, rather than change everything at once and then struggle to understand why it wasn't working.

First I put the Speedtouch in circuit as a conventional PPPoA NAT router, as it comes out of the box, and established that it worked. Then I switched it to PPPoE NAT mode retaining the login username / password on the Speedtouch. That worked too, so then I set about switching to bridge mode.

The instructions at the above entanet page didn't work for me, nor did several others on the internet. Using the command line interface on the Speedtouch is very powerful but some prior knowledge is helpful. I know now that the multiple levels of interfaces have to be dissembled and assembled in order, and most online guides don't do this. The stack of layers looks something like:


So you can't remove or edit an ATM layer if the Ethernet layer that runs on it is still active. The command sequence from entanet missed out the command for the ethernet layer :-

ppp ifdelete intf=Internet
atm ifdetach intf=atm_Internet
To get the second command above to work you have to precede it with
eth ifdetach intf=ethoa_Internet
otherwise you get an obscure error message suggesting you typed the interface name wrong !

A Norwegian called Roy has the simplest approach - tear the lot down and start again - posted on his blog I tweaked this for the UK VPI/VCI settings of 0,38 and reproduce it below :-

ppp relay flush
eth flush
atm flush
ppp flush
atm phonebook flush
atm phonebook add name=BrPPPoE_ph addr=0.38
atm ifadd intf=BrPPPoE_atm
atm ifconfig intf=BrPPPoE_atm dest=BrPPPoE_ph ulp=mac
atm ifattach intf=BrPPPoE_atm
eth bridge ifadd intf=BrPPPoE_br
eth bridge ifconfig intf=BrPPPoE_br dest=BrPPPoE_atm
eth bridge ifattach intf=BrPPPoE_br
This works fine, the Speedtouch becomes a brick with a phone input and an ethernet output and my WRT54GL router running dd-wrt firmware does the PPPoE log in to Enta.

Zen Internet have a template to download to the Speedtouch 5x6 routers, making bridge mode a drop down option. I haven't tried this, but it looks a good place to start if you prefer a point and click solution.

Next time we'll try to use an IPv6 capable device to log in. I have a new Mikrotik router ordered and I'm also waiting for Entanet to confirm they've switch my IPv6 on.


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