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Re: ipv6 dhcp on Technicolor TG582n FTTC

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Ian

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May 26, 2016, 9:44:23 AM5/26/16
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On 25/05/16 09:41, Ian wrote:
> Hi All,
>
> I have a Technicolor TG582n FTTC & Huawei modem pair.
>
> I want to experiment with ipv6 on my local network.
>
> All my ipv6-capable machines seem to have an address fe80:something
> (something about link local, what's that about?). I've figured out the
> commands to add a second static address.
>
> If I read correctly, then is a range of addresses fd00:something which
> are similar to the rfc1918 addresses (194.168.0.0/16 etc), in that they
> will not be routed outside of the local network segment.
>
> How do I get the dhcp server on the Technicolor to issue these ipv6
> addresses?
>
>
> Thanks.
>

Theo Markettos

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May 27, 2016, 7:24:34 PM5/27/16
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Trying again since this seems to have got lost somewhere...

Does your ISP (Plusnet?) give you public IPv6? If so, don't use Unique
Local Addressing as you suggest, use your public address range.

If not, ULA allows local addressing in the range fd00::/7
Pick a subnet[1] and configure your router to broadcast Router Advertisements
with that. If you don't want external connectivity, don't tell it about any
IPv6 routes to the internet. Unlike DHCP, the clients receive RAs and make
up their own addresses - they don't ask the router for an address.

If you don't have public addresses and want them, you can do that via a
tunnel. SIXXS aren't giving out tunnels any more, so the next best bet is
Hurricane Electric.

AA have a nice guide to setting up IPv6 on the Technicolor routers (whose
CLI is a bit unusual):
https://support.aa.net.uk/images/2/20/IPv6_AppNote_v4.0_public.pdf

Theo

[1] https://www.sixxs.net/tools/grh/ula/ is the traditional place

Brian Gregory

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May 29, 2016, 11:34:46 AM5/29/16
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As I understand it the devices make up their own IPv6 local link addresses.
They are not at all the same thing as IPv4 private addresses and can not
be use to communicate with the rest of the internet.
In fact I'm not at all sure what they are supposed to be for.

When you have IPv6 connectivity to the rest of the internet your devices
will get a real public IPv6 address assigned to them (in addition to the
local link IPv6 address).

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

Theo Markettos

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May 29, 2016, 1:32:21 PM5/29/16
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Brian Gregory <bvdvgvrv...@gmail.com> wrote:
> As I understand it the devices make up their own IPv6 local link addresses.
> They are not at all the same thing as IPv4 private addresses and can not
> be use to communicate with the rest of the internet.
> In fact I'm not at all sure what they are supposed to be for.

Link-local is what it says on the tin. Just you and me, with a bit of cat5
between us. No switching, no routing, no subnetting.

It's quite handy because you can join two machines together and the
connection 'just works' - you both have IPs set automatically. On some
systems a hostname map for the other machine appears so you can
connect to it by name. No messing about with static IPs and hosts files.

What the OP proposes is Unique Local Addressing, which is not the same. It's
subnettable and routable, just not publically. It's analogous to RFC1918
addressing in the IPv4 world but the use cases are different.

> When you have IPv6 connectivity to the rest of the internet your devices
> will get a real public IPv6 address assigned to them (in addition to the
> local link IPv6 address).

Indeed. One of the things to understand about IPv6 is it's quite common for
interfaces to have multiple addresses at the same time, and that's perfectly
fine.

Theo

Andy Burns

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May 29, 2016, 2:56:20 PM5/29/16
to
Theo Markettos wrote:

> Link-local is what it says on the tin. Just you and me, with a bit of cat5
> between us. No switching, no routing, no subnetting.

It does also allow for you, me and a bunch of friends connected via a
switch ...

Brian Gregory

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May 29, 2016, 10:19:55 PM5/29/16
to
On 29/05/2016 18:32, Theo Markettos wrote:
> What the OP proposes is Unique Local Addressing, which is not the same. It's
> subnettable and routable, just not publically. It's analogous to RFC1918
> addressing in the IPv4 world but the use cases are different.

If he's just got a TG582n and, one presumes, a single LAN network don't
the link-local addresses do everything he needs?

I'm pretty sure I remember successfully pinging the link-local address
of my router when I was running dual stack. Am I wrong?

Ian

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May 30, 2016, 12:50:11 PM5/30/16
to
On 30/05/16 03:19, Brian Gregory wrote:
> On 29/05/2016 18:32, Theo Markettos wrote:
>> What the OP proposes is Unique Local Addressing, which is not the
>> same. It's
>> subnettable and routable, just not publically. It's analogous to RFC1918
>> addressing in the IPv4 world but the use cases are different.
>
> If he's just got a TG582n and, one presumes, a single LAN network don't
> the link-local addresses do everything he needs?
>
> I'm pretty sure I remember successfully pinging the link-local address
> of my router when I was running dual stack. Am I wrong?
>
Yes, possibly.

I originally couldn't make it work, because linux requires that you
specify the physical interface, as well as the ipv6 number i.e.
fe80::1:2:3:4 doesn't work
fe80:1:2:3:4%eth0 does work

Windows7 doesn't seem to need the interface.

I can't remember about freebsd.

Where do the linklocal addresses come from?
I'm guessing that the machine makes one up at boot time, will a machine
have the same linklocal address every time it starts?

On 29/05/16 18:32, Theo Markettos wrote:
> On some
> systems a hostname map for the other machine appears so you can
> connect to it by name. No messing about with static IPs and hosts
> files.
>
That sounds good, how do I read the hostname map?



Ian

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May 31, 2016, 4:08:20 AM5/31/16
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I found something that says "the linklocal address is generated by
inserting ff:fe into the middle of the mac address, and complementing
the seventh most significant bit". This does hold true for my unix
machines, but not for Win7.


Bob Eager

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May 31, 2016, 4:44:30 AM5/31/16
to
Yes, Vista and beyond do it their own way (typical). You can turn that
off:

https://technet.microsoft.com/en-us/magazine/2007.08.cableguy.aspx

Theo Markettos

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Jun 1, 2016, 5:31:00 PM6/1/16
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Ian <ian@none> wrote:
> On 29/05/16 18:32, Theo Markettos wrote:
> > On some
> > systems a hostname map for the other machine appears so you can
> > connect to it by name. No messing about with static IPs and hosts
> > files.
> >
> That sounds good, how do I read the hostname map?

I think it's using Zeroconf (Bonjour/Avahi) to do multicast DNS, so
you'd need to have that enabled on both ends. I haven't looked into it in
detail, except noticing that it 'just worked' going from Mac to Linux.

Theo

Peter Crosland

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Jun 2, 2016, 5:03:01 PM6/2/16
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On 26/05/2016 14:44, Ian wrote:
There are plenty of routers on the market that will do what you want.
You can replace both your existing pieces of equipment with a VDSL 2
router that will enable you to hide you IP6 addresses from the outside
world.


--
Peter Crosland

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