AW: IPv6 deployment problems over Redback and DSL

Martin Vyskocil mvyskocil at
Thu Jan 17 13:24:30 CET 2008

Hi Jeroen, 

it was not possible for me to estabish a native IPv6 connection
from a router with an ATM line to router with a FR line over the 
public ATM. 
The problem was that the involved ATM-FR packethandler rejected the 
fransfer of frames with unknown tagging (like IPv6).

I used a tunnel over this dedicated line.


> -----Ursprüngliche Nachricht-----
> An: IPv6 Ops list
> Cc: Antonio Querubin
> Betreff: IPv6 deployment problems over Redback and DSL
> Anyone? :)
> Greets,
>   Jeroen
> -------- Original Message --------
> Date: Wed, 16 Jan 2008 23:27:37 -1000 (HST)
> From: Antonio Querubin <tony at>
> To: v6ops at
> Subject: deployment problems over Redback and DSL
> We're testing provisioning of IPv6 to broadband DSL users and 
> have hit a
> snag.  The ILEC that provides us DSL transport does so using 
> a supposedly
> layer-2 transparent system.  The remote DSL site that we're 
> using for this
> test comes in on a frame-relay PVC which we bridge to a VLAN on our
> network.  The VLAN and DSL pass IPv4 traffic without any 
> problems.  The
> VLAN passes IPv6 traffic as well.  However, IPv6 traffic seems to be
> blocked somewhere in the DSL system which consists of a 
> Redback SMS-500,
> the ILEC's frame-relay/ATM network, the remote CO DSLAM and 
> finally the
> remote site DSL CPE (a Westell DSL modem).  The path looks 
> something like
> this:
> VLAN --- Redback SMS-500 --- FR/ATM cloud --- DSLAM --- DSL 
> CPE --- switch
> Currently I suspect the IPv6 ethernet frames are being 
> blocked somewhere
> because IPv6 ND seems to be non-functional in the above 
> network except on
> the VLAN and switch at each end.  I've looked over the manuals for the
> Redback SMS-500 (running AOS 5.0.6) and the Westell DSL modem 
> and neither
> mentions anything specific about filtering or blocking some types of
> ethernet frames.  That would suggest that there's something 
> suspect with
> the ILEC's FR/ATM network or their DSLAMs.  I've asked the 
> ILEC to start
> looking at this problem but I'm also still wary that it may 
> still be an
> issue with the Redback or the Westell modem regardless of what their
> manuals imply.
> Has anyone run into a similar problem before, or have successfully (or
> not) bridged IPv6 over a Redback router or Westell DSL modem?
> Antonio Querubin
> whois:  AQ7-ARIN

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