Greenfield IPv4 + IPv6 broadband deployment

Mikael Abrahamsson swmike at
Sun Feb 27 01:30:22 CET 2011

On Sun, 27 Feb 2011, Adam Armstrong wrote:

> That's the plan currently. Purely layer 2 back a couple of very large devices 
> doing layer 3 aggregation. Still deciding on 1:1 or 1:N VLANs.

I recommend against that. I'd do a lot more distributed L3 switch model, 
let's say one L3 switch per 1000 subscribers or so.

If there was such a device, I'd do L3 switch that the customer connects to 
directly, so you never ever need L2 backhaul and all that pain that comes 
with it (duplicate MAC addresses, needing to handle q-in-q on the L3 
device etc).

I'd also require a CPE to do routing so your big devices never have to 
handle all the customer devices and to ND etc with them. ND is very chatty 
and it's a lot of state to keep, lot's of TCAM slots to handle etc. Do 
link-local only to the customer and do DHCPv6-PD only, no DHCPv6/SLAAC at 
all. If the customer doesn't have a CPE that does this then they won't get 
IPv6, only IPv4+NAT.

> My primary issue at the moment is that I can't see a clean way to manage 100K 
> static v6 prefixes via DHCP.

I'd say you need the equivalent of option 82 and a DB? I don't know how to 
do this currently though.

Mikael Abrahamsson    email: swmike at

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