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New Member

Routing ISP Provided /64 IPv6 prefix

Hi all,

  I am starting out my IPv6 knowledge as my ISP has started provding IPv6 services over 6RD.

I have a router which does my DSL and internet facing NAT, then behind it I have an additional router without DSL that I do all my other stuff on like CME.

So there is a routed hop in between.

My ISP give me a /64 prefix which allows me to do the following to assing to my internal network:

ipv6 general-prefix DELEGATED_PREFIX 6rd Tunnel6

int fa0/0

ipv6 address DELEGATED_PREFIX ::/64 eui-64

My internal router uses autoconfig and finds the /64 prefix and assigns an ip address.  I can ping stuff on the internet from my router, but my hosts behind that router are not within that subnet and as such they don't work.

the DELEGATED_PREFIX changes every time my dsl IP address changes, so statically setting up two /65 subnets (one for transit between and the other for hosts) is not practical.

Is there a way I can acheive what I am trying to do, while maintaining the dynamic nature of 6RD?




Re: Routing ISP Provided /64 IPv6 prefix

Hi there,

I was thinking, you could create a Tunnel interface between your internal Router and DSL router, set it with ipv6 and config a default route pointing to that tunnel int. use link local ipv6 addresses for ur clients and NAT them later.

plz Rate if it helped.


Hope it Helps, Soroush.
New Member

Re: Routing ISP Provided /64 IPv6 prefix

There is no overload NAT like in IPv4, only 4to6 and 6to4 which won't give me what I need.

Doing some research, moving away from /64 subnets means that I have to move to a DHCPv6 scenario and with my IPv6 subnet changing with my IP address (dynamic ipv4 with PPPoE) then I would have to do come complex EEM scipting to update the subnet on my internal router.

I solved this by creating sub interfaces, keeping the transfer network for the IPv4 but using bridging on the internal router between the host vlan and another sub int which has the IPv6 part on it.

It is awful, but it works and by and large simulates a typical consumer scenario.

My house is now dual stacked.