Question about migrating to IPv6 with multiple upstreams.

Matthew Reath matt at
Sun Jun 12 04:00:45 UTC 2011

>> -----Original Message-----
>> From: Matthew Reath [mailto:matt at]
>> Sent: June-11-11 11:22 PM
>> To: Randy Carpenter
>> Cc: nanog at
>> Subject: Re: Question about migrating to IPv6 with multiple upstreams.
>> Standard IP routing, the default gateway of the network can decide based
>> on a route entry whether to send it to the cable modem or send it to the
>> firewall.
> If the source block is not routed via both connections it won't work
> without
> NAT.  I had this same problem trying to use my ISP's native v6 over PPPoE
> and maintain a tunnel as backup since it was still pretty flaky as they
> were
> testing it at the time ... no way a residential ISP is going to route 3rd
> party blocks for all their customers, and no chance the tunnel provider
> was
> going to route the block my ISP assigned me either ... with no NAT66 in
> Tomato/ddWRT/etc it was 100% impossible to have multiple connections ...

I guess I'm a little confused on the setup. You have a firewall with a
connection to a local LAN, another connection to customer network(s), and
a third connection to the Internet via cable modem?

You have NAT setup to NAT your Local LAN out to the Internet and to the
customer network? A customer network device would use the outside IP on
the customer network connection to communicate with devices in the Local

I think it makes more sense to me now.

Matt Reath
CCIE #27316 (SP)
matt at |

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