using ULA for 'hidden' v6 devices?

Mark Andrews marka at
Fri Jan 27 03:11:33 UTC 2012

In message <20120127015842.GH6332 at angus.ind.WPI.EDU>, Chuck Anderson writes:
> On Thu, Jan 26, 2012 at 07:53:18PM +0000, George Bonser wrote:
> > > Even if you don't see an advantage to GUA, can you point to a
> > > disadvantage?
> > 
> > Just a matter of convenience.  If you have a lot of management IPs or some 
> other IP addresses that are never going to need internet access (an array of 
> 10,000 sensors or something) you don't need to dip into your global allocatio
> n to address them.  If it is routed within the organization but never goes to
>  the Internet, ULA is ok.  If it doesn't get routed at all, link local will d
> o fine.   It's good to keep in mind that more things than computers with web 
> browsers are going to get an IP address.
> Link-local won't do fine in many cases due to poor application
> compatibilty with address scopes.

Link local is a right royal pain for applications.  The DNS does
not support it.  It requires passing arount 150 bits of address
information instead of 128.

Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at

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