Subnetting /48: rtadvd daemons and different locations

[jollino]

Hello all again, here I am with another probably very simple question. I've been searching an answer to this, but I haven't found a definitive answer.

Let's suppose I want to split a /48 (either tunneled or native, it doesn't matter) into a few different /64 subnets, and that I have a machine acting as a gateway for the whole /48, so I can easily assign addresses in each /64 subnet as long as they can reach the gateway /48. However, what if I wanted to have router advertisement in each subnet? Having a single daemon on the /48 gateway wouldn't really work (how to differentiate between subnets?), so I imagine that each subnet should have its own. What is the correct way of doing this? Should each subnet have its own gateway — the only one phyiscally reaching the "main" gateway handling the whole /48 — that runs a rtadvd daemon for its nodes?

Also, let's say I have several physical locations, each with its own internet connection (ie. no direct local link between them), and I want each of them to use a different /64 subnet belonging to my greater /48. Creating two different tunnels would result in two different /64s, and now that I think of it, even native IPv6 will cause the locations to be on entirely different /64. So, is such a thing even possible without resorting to setting up a VPN?

Thank you in advance... for the replies and for your patience. :D

[cholzhauer]

However, what if I wanted to have router advertisement in each subnet? Having a single daemon on the /48 gateway wouldn't really work (how to differentiate between subnets?), so I imagine that each subnet should have its own. What is the correct way of do

You can tell the RA daemon to advertise on certain interfaces.  So, if you wanted 2001:db8:1:1::/64 on eth0 and 2001:db8:1:2::/64 on eth1, you could do that.  Your gateway needs to have an interface on every subnet you want to advertise on, but aside from that, it's pretty easy to set up.

Also, let's say I have several physical locations, each with its own internet connection (ie. no direct local link between them), and I want each of them to use a different /64 subnet belonging to my greater /48. Creating two different tunnels would result in two different /64s, and now that I think of it, even native IPv6 will cause the locations to be on entirely different /64. So, is such a thing even possible without resorting to setting up a VPN?

You're right; you need to create some sort of tunnel between the two locations so they could talk directly to each other.

[jollino]

You can tell the RA daemon to advertise on certain interfaces.  So, if you wanted 2001:db8:1:1::/64 on eth0 and 2001:db8:1:2::/64 on eth1, you could do that.  Your gateway needs to have an interface on every subnet you want to advertise on, but aside from that, it's pretty easy to set up.

So the subnets have to be physically independent from one another, linked only by the gateway itself in a star topology. Got it.

You're right; you need to create some sort of tunnel between the two locations so they could talk directly to each other.

I'll need to look into 'creating' v4 tunnels, then. :) This may come in handy in a short while...