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IPV6 on your LAN

Community Veteran
Posts: 1,236
Registered: 02-08-2007

IPV6 on your LAN

I am thinking of switching entirely to IPV6 (as much as possible) both internally and externally on my home network in the next few months.
I have a /48 with my ISP which I can use whenever I want. They have been offering IPV6 to clients for 10 years now. I have been irritated recently by a continuous barrage of DNS queries to an IP in my current /27 IPV4 subnet that is not even in use any more but the traffic still gets to my router and then it continuously arps internally for the address. Not much of an issue but just irritating because there is little I can do about it. I figure switching to IPv6 will be one good way to stop this kind of thing permanently.
My plan is to switch my Netgear DG834 to modem only mode and have a Cisco 2621 control the PPPoE connection as the DG834 won't support IPv6 as far as I can see. In the medium term I would swap the 2621 for an ASA 5505.
I have a small number of devices internally that will not support IPv6, for example, 2 Sky HD boxes. For those devices I plan to use Cisco NAT-PT.
I am thinking it is best to get a good understanding and experience with IPv6 now before we all become more and more pressured into doing so.
Has anyone tried on on a LAN? Any experiences?
6 REPLIES
David_W
Rising Star
Posts: 2,293
Thanks: 29
Registered: 19-07-2007

Re: IPV6 on your LAN

Quote from: Sean
I am thinking it is best to get a good understanding and experience with IPv6 now before we all become more and more pressured into doing so.

I read a comment recently by one of the tech guru's about IPV6.  Their basic mantra is "if you need to do anything to make it work, it's not working properly" or words to that effect, they simply want it to be as seamless as IPV4, it "just works" (wonder where I stole that from).  I don't think it's possible to have a pure IPV6 network, it had to be dual 4/6 else the vast majority of the internet will just stop working, though for things which are network based but have no need to access the internet a pure IPV6 solution would work (like NAS) but again, you may then have devices which need to access that device which themselves don't support IPV6.
I guess you could split things up neatly.  Things which need internet access (IPV4/6) - Things which don't need internet access (next chart (2)) - (2) things which have IPV4 only devices that require connecting (IPv4/6) - (2) things which don't have IPV4 only devices that require connecting (IPV6).  The aforementioned NAS, the only things that should connect to it are computers so IPV6 only should work (if it supports it) but then the NAS may have advanced features which require internet access so it'll be in the 4/6 category.  In the end you may find that you have nothing which doesn't in some way rely on IPV4 which would make an IPV6 only solution impractical?
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: IPV6 on your LAN

I think for the average home user with an IPv6 capable router and DHCPv6 it will "just work", but for people like me who work in IT, largely in the area of networking, the whole move to IPv6 is definitely going to take a lot of input, learning and testing to get ourselves familiar.
I will be honest and say that I have only started looking closely at it very recently but already the logic behind it is getting me very excited and the fact that I have 1208925819614629174706176 public IP addresses on my ADSL connection provided by my ISP totally blows my mind!
I already have my internal network logically sub-netted / vlaned with a Cisco 2621 "router on a stick" doing all the inter-vlan routing.
Almost everything, desktops, laptops, mailserver, webserver, fileserver are either Windows 7 or CentOS 5 so IPv6 is no issue there.
The areas where I do see issues, Sky boxes (Anytime+), wireless AP, Cisco 2950 management vlan interface.
For those devices I can just use Cisco NAT-PT to "121" nat them across to the IPv6 network and also onto the internet. There is no reason why they cannot have internet access. Maybe I have over simplified the whole process in my head?
Community Veteran
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Registered: 24-09-2008

Re: IPV6 on your LAN

I think the Linksys-wireless G I'm running is on IPV6 (following from ipconfigSmiley, seems to work OK,
Quote
  Connection-specific DNS Suffix  . :
  Link-local IPv6 Address . . . . . : fe80::e867:15cc:e2e1:5645%19
  IPv4 Address. . . . . . . . . . . : 192.168.1.101
  Subnet Mask . . . . . . . . . . . : 255.255.255.0
  Default Gateway . . . . . . . . . : 192.168.1.1
Tunnel adapter Teredo Tunneling Pseudo-Interface:
  Connection-specific DNS Suffix  . :
  IPv6 Address. . . . . . . . . . . : 2001:0:5ef5:79fd:10e3:38b6:3f57:fe9a
  Link-local IPv6 Address . . . . . : fe80::10e3:38b6:3f57:fe9a%16
  Default Gateway . . . . . . . . . : ::
David_W
Rising Star
Posts: 2,293
Thanks: 29
Registered: 19-07-2007

Re: IPV6 on your LAN

A quick google shows that NAT-PT has lots of problems so has been depreciated and shouldn't be used, this link has a bit more info from Cisco which if I'm reading it correctly means you could switch your entire network to IPV6 (where supported) and the router would do all the conversions using stateless NAT64.  One of the problems with using NAT-PT is that a future IOS update could remove it from the firmware which would break stuff.
Community Veteran
Posts: 1,236
Registered: 02-08-2007

Re: IPV6 on your LAN

I had also noticed hat NAT-PT was depreciated but I was thinking of using it at least only short term to get me up and running. The NAT-PT configs on Cisco sites look very straight forward, not much different to standard NAT.
I may be limited by the fact that I am using Cisco 2621's routers. I have already upgraded the flash and the RAM and the ios to support Crypto services. I am not sure where I might stand with newer, better ways to get between IPv4 and IPv6.
I need to do a lot of testing after the holidays to find out exactly what I can and cannot do with the 2600 series routers in order to acheive this.
David_W
Rising Star
Posts: 2,293
Thanks: 29
Registered: 19-07-2007

Re: IPV6 on your LAN

Having a quick look on Cisco's site it appears IOS only supports NAT-PT and only on the 12/15.x.T line of firmwares, though thinking about it, when Cisco depreciate or remove a function on an upgrade it usually changes the config to work with the new settings, sometimes to detrimental effects.