IPv6, DHCP and DrayTek router...?

esuhl

I'm (still) trying to get my head round IPv6, and how to set it up on my DrayTek Vigor 2830n router.

Until now, I'd disabled IPv6. But (for the sheer geekery) I want to understand and enable it.

With IPv4, a WAN interface gets a public IP address, and NAT and DHCP are used to allocate private IPv4 addresses to local devices.

But how does this work with IPv6? There are options to use DHCP with IPv6 on my router. So... do I only get one IPv6 address from my ISP and NAT/DHCP are still used on the LAN? Or does the DHCP server on my router just pass on the request to my ISP's DHCP server to allocate a new IPv6 address?

Also, I understand that an IPv6 address can be associated with a device's MAC address (causing privacy issues), and that IPv6 devices can use randomly generated temporary IPv6 addresses. How do I enable that, and how does it work (via DHCP?)?

Lastly, any tips for what settings I should enter on the router? What's RADVD, for example? Should I enable it on a simple home network?

Screenshot: https://www.dropbox.com/s/x20jgn6xvmt69qz/DrayTek%20IPv6%20screen.PNG?dl=0

(Oh, and does anyone know what Sky's IPv6 DNS servers are?)

Thanks for any tips!

I_have_spoken

> So... do I only get one IPv6 address from my ISP and NAT/DHCP are still used on the LAN?<

If your ISP supports IPv6 then an IPv6 enabled router will generally ask for a delegation prefix, giving the first part of an IPv6 address. The router will then allocate full IPv6 addresses that make up a subnet based on the prefix. Most delegation prefix still allow for 1,000s of unique addresses in the subnet.

TBH, you may be better swapping back the Sky hub and get IPv6 working with their kit. Unless the Draytek does DHCP-PD (Prefix Delegation) you may be out of luck.

AndyPix

IPv6 is the work of the devil .. and should be killed in it's sleep

esuhl

I_have_spoken wrote: »

> So... do I only get one IPv6 address from my ISP and NAT/DHCP are still used on the LAN?<

If your ISP supports IPv6 then an IPv6 enabled router will generally ask for a delegation prefix, giving the first part of an IPv6 address. The router will then allocate full IPv6 addresses that make up a subnet based on the prefix. Most delegation prefix still allow for 1,000s of unique addresses in the subnet.

TBH, you may be better swapping back the Sky hub and get IPv6 working with their kit. Unless the Draytek does DHCP-PD (Prefix Delegation) you may be out of luck.

Ah, right. Thanks. Looking again at the manual, it looks like my router supports "prefix delegation", and that the router's DHCPv6 server is what makes that work.

But I'm still a bit confused as to how temporary (as opposed to device-specific) IPv6 addresses are allocated. I guess the DHCPv6 server takes care of that too? :-/

I might plug in the Sky router again to have a look at the settings.

AndyPix wrote: »

IPv6 is the work of the devil .. and should be killed in it's sleep

Better the devil you know.

dj1471

Your ISP will allocate a block of address to you, usually a /64. There are several different ways the router can pick this up from the ISP.

The router will then advertise this prefix to all of your hosts who will generate an IPv6 address based on their MAC address. Again there are several different ways this can happen, DHCPv6 is common but not actually required if all you want to assign is an IP address.

See SLAAC

You don't need to use a DNS server over IPv6 to lookup IPv6 addressees.

All you should need to do is enable IPv6 and DHCPv6 and everything should just work, assuming your hosts haven't got IPv6 disabled.

Try http://ipv6test.google.com.

I_have_spoken

There's more advice over on the Sky support forums

spenderdave

Many non-Sky routers don't support the /56 prefix delegation that Sky and BT use. I tried to get my TP-Link router to work but it wouldn't so using the Sky SR102 which just works.

onomatopoeia99

AndyPix wrote: »

IPv6 is the work of the devil .. and should be killed in it's sleep

NAT is evil and should never have been born

I'd rather a protocol that allows every device to be uniquely addressable, than a bodge to overcome the 2^32 address limit that IPv4 imposes.

John_Gray

onomatopoeia99 wrote: »

I'd rather a protocol that allows every device to be uniquely addressable,,,

But what if you actually don't want your devices to be globally addressable?

dj1471

John_Gray wrote: »

But what if you actually don't want your devices to be globally addressable?

Why wouldn't you?

You're behind a firewall, so...? All of your devices can already be uniquely identified using other means (cookies, browser UA string, etc etc).

onomatopoeia99

John_Gray wrote: »

But what if you actually don't want your devices to be globally addressable?

I cannot think of a reason why you would not want them to.

NAT is not a firewall.