On Oct 23, 2009, at 5:08 AM, Perry Lorier wrote:
WRT "Anycast DNS"; Perhaps a special-case of ULA, FD00::53?
You want to allow for more than one for obvious fault isolation and load balancing reasons. The draft suggested using <prefix>:FFFF::1 I personally would suggest getting a well known ULA-C allocation assigned to IANA, then use <prefix>::<protocol assignment>:1 <prefix>::<protocol assignment>:2 and <prefix>::<protocol assignment>:3, where <protocol assignment> could be "0035" for DNS, and "007b" for NTP, and if you're feeling adventurous you could use "0019" for outgoing SMTP relay.
I thought ULA-C was dead... Did someone resurrect this unfortunate bad idea?
I'm not sure, I've not checked for a pulse recently. Last I looked it seemed that there was ULA-L and ULA-C, and most people were saying use ULA-L unless you needed ULA-C, ULA-C seemed like a good fit for this, if it's been buried then sure ULA-L would fit the bill just as well.
Easily identified, not globally routable, can be pre-programmed in implementations/applications ... ?
Exactly, seems easy, straight forward, robust, reliable and allows for things like fate sharing and fail over.
Why pull this out of ULA? Why not pull it out of 0000/16 or one of the other reserved prefixes?
With my proposal above it only requires a /96, seems silly to use up an entire /16 on a /96 worth of bits. It shouldn't come out of 2000::/3 because that's globally routable and this is defined to sit within locally scoped addressing.
No... You missed my point... I was suggesting that 0000::/16 already had some assignments for stuff somewhat like this, so, why not use more of that prefix to get a /96 for this... e.g. ::/0 == default, ::1/128 == Loopback, etc. Why not use 0000:ffff::/64 to assign these addresses as: 0000:ffff::<inst:ance>:<serv:ice> That is a 32 bit instance number and 32 bit port number, using up just a /64. I was not suggesting the entire /16 for this, the entire /16 there isn't available.
I have no major thoughts either way as to exactly where the range comes from other than it should be an easy to spot, and easy to type range which suggests plenty of 0's :)
I figured 0000 was a good candidate since it's already partially in use for reserved special addresses. Owen