Using IPv6 with prefixes shorter than a /64 on a LAN

Jack Bates jbates at
Tue Feb 1 09:43:47 CST 2011

On 2/1/2011 9:23 AM, Tim Franklin wrote:
> I really,*really*  expect my CPE router*not*  to remove global
> addresses from the LAN interface(s) when the link to the Internet
> goes down.  My internal services should go on working with their
> global addresses.  This is how my tunneled IPv6 works today.
> Am I being an unreasonable engineer in this respect?

This depends. Will you have a static assignment? What will be the 
lifetime values issued by your ISP? Granted, You should be able to 
maintain them at least 2 hours, though in a multiple router scenario, 
I'm not sure how well they'll take to routing unpreferred prefixes.

ULA isn't a bad thing. It also doesn't interfere with your GUA. There's 
really no reason NOT to have ULA in CPE devices. If your DSL is down for 
a day or two, do you really want to worry about addressing? Do you want 
to connect to the Internet before you can have addressing?


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