Subject: deployment problems over Redback and DSL

From: Antonio Querubin <[email-masked]>
Date: Wed, 16 Jan 2008 23:27:37 -1000 (HST)

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

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Thu, 17 Jan 2008 11:10:52 +0100

On 17 jan 2008, at 10:27, Antonio Querubin wrote:

> 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 encountered the situation where ND wouldn't work before on  
Extreme multilayer switches, which implement(ed?) IGMP snooping such  
that multicasts aren't forwarded without IGMP, even if those are non- 
IPv4 multicasts that by definition can't have corresponding IGMP  
messages. So see if you can get IGMP snooping disabled, or set up some  
static ND entries and see if unicast IPv6 traffic makes it through.