nanog mailing list archives

RE: IPv6 Deployment for the LAN ... anycast


From: "TJ" <trejrco () gmail com>
Date: Fri, 23 Oct 2009 00:38:31 -0400

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

FWIW - I think simple anycast fits that bill.


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.

IMHO non-hex-converted port numbers works cleanly ... ?


I thought ULA-C was dead... Did someone resurrect this unfortunate bad
idea?

Anything is dead until someone uses it.
I was thinking FD00 just to have symmetry with anyone using ULAs today, so
FC00::/8 could be outright blocked ... ?
FC may make sense as they are, de facto, registered ...


... Heck, start a registry (@IANA) and add in FD00::101, etc. ...
Maybe reserve FD00::/96 for this type of "ULA port-based anycast
allocation". (16bits would only reach 9999 w/o hex-conversion (if
hex-converted could reserve FD00::/112 ... But would be less
obvious))

Thinking further, if simply based on port#s wouldn't even need a registry.
Unless it was decided to implement the multiple-addresses-per-function
mentioned above, then perhaps useful.


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?

ULAs are already defined as "internally routable, but not globally routable"
- which is exactly how I would envision these being used.
IOW, seemed to make sense to me!


/TJ




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