IPv4 to IPv6...

[Lennart Sorensen]

On Wed, Oct 06, 2010 at 12:06:27PM -0400, James Knott wrote:
> Perhaps I'm being overly economical with words.  When you connect via  
> ADSL you are using IP over ethernet.  In my previous note, the ethernet  
> was assumed.  Now, that IP gets stuffed into PPPoE to the ISP.  This  
> might be described as layer 3 on layer 2 on layer 2, with PPPoE being  
> the extra layer 2.

You can run ADSL in pure bridged ethernet mode (which doesn't hence
have PPPoE) if you have a direct connection to the DSLAM of the ISP.
Teksavvy has that service in some places.  Some business services from
Bell also work that way.  Most connections use PPPoE instead, which
permits Bell to route the PPP packets to an ISP over a shared network
and hence doesn't require the ISP to have their own equipment at the C.O.

> Perhaps I should have said ADSL service.  Right now, with most ISPs  
> you'd have a tough time passing IPv6 traffic, because all the equipment  
> is not configured to handle it.  If Teksavvy had their own DSLAMs in the  
> Bell CO, then it would be easier for them to provide IPv6 support  
> (they'd also avoid Bell throttling), as PPP, including PPPoE will  
> support almost any packet based protocol.  The big problem is how the  
> various devices are configured.  When you have an ADSL connection, the  
> equipment commonly used is expecting IPv4 and nothing else.  Will the  
> basic ADSL modem, as provided by Bell etc., support multiple protocols?   
> Or will it filter out those other protocols? (I realize D.H.R. has a  
> basic ethernet ADSL modem)  What about the equipment back at the C.O.?   
> The DSLAM shelves I've worked with supported only IPv4 (It's been about  
> 5 years since I've worked on a DSLAM in a C.O., but I have worked on  
> others, in corporate networks more recently.  I have also worked with  
> SHDSL gear, TSUs and short haul microwave that didn't care, as they were  
> were configured as an ethernet bridge.).  Hopefully equipment suppliers  
> are starting to take the hint, as I've seen some consumer level routers  
> that now support IPv6, as does Cisco gear.  Last time I was talking to  
> an Adtran engineer, it was still "in development" with no target dates.   
> On the cable modem side, DOCSIS 3 supports IPv6 as part of the standard  
> and there's an update for DOCSIS 2.  Will Rogers provide an update for  
> my modem?  Or will I have to buy a new one?

Well I don't think Bell's network needs to know anything about IP.

The PPP connection request (which is a layer2 control packet, NOT
IP), contains the username, which is used to route the connection to
the correct ISP.  Once it reaches the ISP, the PPP link can negotaite
between the end user and the ISP.  That negotiation then provides an IP
link on top of PPP.  So at no point does Bell care what kind of traffic
PPP is going to carry.  To Bell they are all PPP packets and what is
inside is irrelevant.  This is also how teksavvy can support MLPPP even
though Bell doesn't.  It happens to also conviniently confuse Bell's
throthling box because it doesn't understand MLPPP packets, even though
Bell's network has no problem moving them (after all MLPPP packets are
still perfectly normal PPP packets).

So if the ISP supports IPv6 on PPP (and teksavvy does) and the end user
supports IPv6 on PPP (which the modified router teksavvy is selling does),
then you can get native IPv6 over PPP.

In the case of the cable modem, they seem to use MAC addreses on each
modem and essentially appear as ethernet bridges and even use DHCP
(which really only works on ethernet like networks), so I would be
surprised if DOCSIS had any part in which version of IP they can run.
It would seem like a design mistake if they needed to know.  Of course
that doesn't mean they didn't make such a design mistake.

> However, even when the equipment supports IPv6, the ISPs and carriers  
> also have to get off their butts.  A few months ago, I was talking to a  
> hosting site manager for a major ISP/telecom and he said they had no  
> plans for IPv6.  Teksavvy appears to be an exception to this and I  
> believe Telus is also working on setting up IPv6 support.

It seems many telco's hate spending money on infastructure if they can
see any way to avoid it.  After all they are making lots of money now
with what they have, and they don't know if the new stuff will make them
more money, so why take a risk.

-- 
Len Sorensen
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