Introducing draft-denog-v6ops-addresspartnaming

William Herrin bill at
Sun Nov 21 16:50:07 CST 2010

On Sun, Nov 21, 2010 at 11:40 AM, Joel Jaeggli <joelja at> wrote:
> There is a lot of assumption on the part of ipv6 that the use of ipv6
> literals in uri's would be a rather infrequent occurrence, given how
> infrequent it is in ipv4 it would seem to be a reasonable assumption.


Looks like an ass-u-me. If you think the use if IPv4 addresses in URLs
is infrequent, it's mostly "u." Get out in the field some time.

I've yet to work for a non-ISP that (before I arrived) maintained
their internal DNS consistently vice using address literals. If the
company was small, they didn't really know how to operate a DNS
server. If large, the DNS ops were too inaccessible to be consulted on
things that weren't also being reviewed by PR for release to the
general public.

In fact, in one project I occasionally work on, the team is
-frequently- told by the DNS op for the NIPR-based DNS server how
bothered he is by the lookup count, so won't we please place commonly
used Internet names in our /etc/hosts. My jaw dropped the first time I
heard that one.

That server op is the kind of guy we're asking to understand that
there's nothing special about the two bytes between the colons in the
IPv6 address. He's gonna be trouble.

On Sun, Nov 21, 2010 at 1:42 PM,  <Valdis.Kletnieks at> wrote:
> On Sat, 20 Nov 2010 12:12:09 EST, William Herrin said:
>> 260:abcde:123456:98::1
>> 260 - IANA to ARIN, a /12
>> abcde - ARIN to ISP, a /32
>> 123456 - ISP to customer, a /56
>> 98 - customer subnet
>> ::1 - LAN address
> What do you do when ARIN gives Tier1 a /24, and Tier1 gives Billy Bob's
> Bait, Tackle, and Internet a /40, and Billy Bob gives one of their customers a /56?

Whatever you want to do. That's the point of optional/movable separators.

An option w/ movable separators:


Actual IPv6 standard (and also allowed w/ movable separators):


On Sun, Nov 21, 2010 at 5:15 PM, Owen DeLong <owen at> wrote:
>> Imea nrea lly, what ifwe wrot eEng lish thew aywe writ eIPv 6add ress
>> es? Looks pretty stupid without a floating separator, doesn't it?
> If this were prose, sure. It isn't. It's an addressing scheme. I mean,
> really, we don't question 99999-1520 or 408-555-1212 which
> are much more like what we're talking about.
> In fact, it would look pretty weird to most people if we started writing
> 951-21-42-33 (or I bet they wouldn't expect that was a zip code in
> any case). Similarly, if we start placing the separators in arbitrary
> places in phone numbers, people get confused.

That would be a more compelling argument if it accurately described
phone number notation. It doesn't. "+44 121 410 5228," for example, is
the phone number for parking services at Heathrow airport, exactly as
described on's "contact us" page. No
dashes at all, and not 10 digits.

And BTW, 408-555-1212 isn't arbitrarily separated. Each component has
a specific meaning. Long distance region 408, telco reserved prefix
555, long distance information 1212.

The Zip code's components also have meaning. The left 5 digits
indicate the specific post office and the right 4 digits usually
specify the internal box number used for sorting the mail.

Even IPv4's dot separators were placed in meaningful locations in the
original Classful design. The network address was always the whole
content to the left of one of the dots while the host address was
always the whole content to the right. Unless the network was complex
enough to have a subnet address in the middle, still confined by the
dots. It's an anachronism now, but the separators were originally

IPv6 is one of very few addressing schemes in which the separators
intentionally have no greater meaning within the protocol or its use.
They're just there. If we want folks to understand that difference
from their normal experience with addressing notations, we'll have to
call attention to it by, for example, leaving the byte groupings
formally unnamed.

>>> Dash is a poor choice because it becomes potentially problematic
>>> to know whether your cisco is telling you that:
>>> 2001-0db8-5f03 is a MAC address or a /48 prefix.
>> Cisco's expression of a MAC address is wrong anyway. Correct notation
>> for a MAC address is separating each byte with a colon.
> Doesn't matter... It's widespread and Cisco isn't the only one to use it.

Just for my own edification, who else besides Cisco do you know who
uses that notation for MAC addresses? I want some convincing before
I'll accept the claim that it's widespread.


William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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