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Author Topic: IPv6 subnetting and addressing  (Read 20977 times)

jroy

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IPv6 subnetting and addressing
« on: February 11, 2008, 03:50:20 PM »

When we receive a /64 from you (awesome service BTW) do we use the next 16 bits only for subnetting? I have read a few docs and an not absolutely sure. Do you have simplified reference you can offer?

TIA

jroy%remotehand*com
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samh

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Re: IPv6 subnetting and addressing
« Reply #1 on: February 11, 2008, 06:39:27 PM »

For the routed /64 we are simply adding an ipv6 route <routed/64> <tunnel/64customerendpoint> so that means you have all 64 bits after the initial to do subnetting with.

So if you have :
2001:0470:1f01:0012::/64 routed to you you could for example break out:

2001:0470:1f01:0012:0001::/96
2001:0470:1f01:0012:0002::/96

etc...

Sam
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mindlesstux

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Re: IPv6 subnetting and addressing
« Reply #2 on: February 11, 2008, 09:35:23 PM »

Well I thought I would give a small go at breaking the /64 up into /80's so that I could use one part for LAN and one for VPN on my little home network.  But as soon as I did that, my linux box started complaining...

/var/log/messages
Feb 12 00:25:29 atlantis IPv6 addrconf: prefix with wrong length 80

I could not find any info as to why it would be doing that...

(BTW using a cisco router as the endpoint of which found bridging and ipv6 are not friends...)
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samh

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Re: IPv6 subnetting and addressing
« Reply #3 on: February 12, 2008, 02:18:21 PM »

Can you give us a sanatized (Remove any passwords etc) copy of what steps your taking to acomplish this?  WIthout defining what address' you try to set I cant verify why you would see this problem from linux. 

If youd like to start a new thread or just followup in this one with your config id be happy to look into it.

Sam

Well I thought I would give a small go at breaking the /64 up into /80's so that I could use one part for LAN and one for VPN on my little home network.  But as soon as I did that, my linux box started complaining...

/var/log/messages
Feb 12 00:25:29 atlantis IPv6 addrconf: prefix with wrong length 80

I could not find any info as to why it would be doing that...

(BTW using a cisco router as the endpoint of which found bridging and ipv6 are not friends...)
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baerm

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Re: IPv6 subnetting and addressing
« Reply #4 on: February 15, 2008, 09:09:03 AM »


This looks familiar to what I've seen.  If I remember correctly, this message is from the autoconfiguration of an interface.  IPv6 autoconfiguration requires /64 networks.  If you want to run a different size network (/80 or whatever), you'll need to configure the network without autoconfiguration (by hand and/or dhcp server, etc).  It may be that you are configuring the interface manually, but the interface is also set to autoconf (i.e. /etc/sysconfig/network-scripts/ifcfg-eth0 has 'IPV6_AUTOCONF=yes' or there should be a switch somewhere in the system-config-network GUI you can toggle instead).  It is perfectly fine to have multiple addresses on an interface so you could in theory have an interface withe an autoconfigured and a manually configured address, but it probably isn't what you want here :).

-Mike
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