ULAs [was: ipv6-ops Digest, Vol 159, Issue 1]

[Brian E Carpenter]

<gripe>Please don't send mail with useless "Digest" subject headers.</gripe>

Michael, sorry to be blunt but you seem to have misunderstood ULAs.

My ULA prefix, for example, is fd63:45eb:dc14::/48 but my CE assigns addresses
in the subnet fd63:45eb:dc14::/64. If I ran a routed network at home, the routers
would each manage a different subnet in fd63:45eb:dc14::/48 and ULAs are
routeable within all those subnets, but are filtered at the CE/WAN interface.

It's correct that fc00::/8 is not used; all current ULA usage is in fd00::/8.
But so what? fc00::/8 is reserved for future use.

It is entirely possible for nodes within a SOHO network to be assigned ULAs only
(and therefore have no possibility of external access) or to be assigned both
ULAs and global addresses (for internal and external traffic respectively).
Sadly the makers of printers etc still have to catch up with that. But some
CEs, such as my rather ancient FritzBox, handle this very well.

You could look at
https://tools.ietf.org/html/draft-ietf-v6ops-ula-usage-considerations-02
although that draft was never approved for RFC status.

Regards
   Brian Carpenter

On 24-Oct-19 04:51, Michael Sturtz wrote:
> The only current RFC on ULA is fc00::/7 but fc00::/8 remains undefined and has not been accepted by IETF. The block fd00::/8 can be divided up.  All of this said none of these addresses would be routable on the internet and since a lot of the end user equipment can't handle a statically configured ULA address and still obtain a routable address from SLAAC or DHCP6.  This creates major problems for networks with limited IT support.  On larger corporate networks with skilled IT people it's very likely that they will have a static allocation from an ISP however smaller networks without IT people it can become a serious problem.  Those people won't be skilled enough to figure out ULAs anyway.  
> 
> -----Original Message-----
> From: Gert Doering <gert at space.net> 
> Sent: Wednesday, October 23, 2019 8:28 AM
> To: Michael Sturtz <Michael.Sturtz at PACCAR.com>
> Cc: Kristian McColm <Kristian.McColm at rci.rogers.com>; ipv6-ops at lists.cluenet.de
> Subject: Re: ipv6-ops Digest, Vol 159, Issue 1
> 
> Hi,
> 
> On Wed, Oct 23, 2019 at 03:00:21PM +0000, Michael Sturtz wrote:
>> As far as I know ULA was deprecated in 9/2004 
> 
> Those were site-locals, not ULAs.
> 
> Gert Doering
>         -- NetMaster
>