169.254.0.0/16

Thu Oct 18 15:18:56 UTC 2012

On Wed, Oct 17, 2012 at 06:59:09PM +0100, Darren O'Connor wrote:
> I've just set up a vpn tunnel to Amazon's AWS and as part of the config 
> they required me to configure to /30 tunnels using addressing from the 
> 169.254.0.0/16 space.

	Yeah, they do that for Direct Connect.

> RFC3927 basically says that this address should only be used as a temp 
> measure until the interface has a proper private or public address.

	So? :)

> So what's the consensus then? Is their a problem using this space as 
> link-local address for routers here and there (I mean we have 65K 
> addresses wasted in this block) or is it a strict no-no? And if no, why 
> is Amazon using it?

	RFCs are just paper.  As for why they use it.. the common private
use reserved blocks (10/8, 172.16/12, 192.168/16) are all in use 
internally in their customers networks.  This is probably the easiest
way to avoid addressing conflicts.

	Since these networks are all isolated, I don't see a great deal
of harm in it (probably less than overlapping more commonly used private
blocks.)

	--msa