TJ wrote:
"yet it's hard to extend a common IPv6 subnet"
I'm sorry, extend in what fashion? You mean in order to have 2 (or,
"n") subnets?
Yes, that, it's hard to add a new unplanned-for-initially Ethernet
subnet to an existing subnet which is allocated a /64 prefix.
"or one needs to be allocated a shorter than /64 prefix (e.g. be
allocated a /56). These are rare"
They are? I must have missed that memo! (Sorry, don't mean to be
overly flippant) Seriously, last time I checked I could get up to a
/48 (or, atleast a /56) fairly readily ... that is the whole point,
and if someone is making that difficult for you that is a different
conversation!
Well yes, I suppose if one asks an allocating organization for a /48
prefix then one may obtain it easily. However, one must be sysadmin to
know one can obtain that. A more mere mortal doesn't even know such
organizations exist, and uses whatever is available at hand. There are
more mere mortals than sysadmins, hence that is rare.
If I arrive to a /64 wifi hotspot in a hotel room I can't extend it with
another subnet, on which to plug my other IPv6 wifi devices.
Also, if I plan my (fictitious) lab network with core routers and such
and prepare for 15 edge /64bit networks, I won't be able to extend them
in a few years with more edge networks without manually changing the
addressing in the core routers.
If I want to build a WiFi router (not bridge), which plugs itself into
an IPv6 wired network, autoconfigures itself, and delivers IPv6 on the
wifi part - it's hardly possible, because the IPv6 wired network on
which I plug this AP is hardly extensible.
People have already deployed many /64 Ethernet networks - they're all
hard to extend.
This is lack of extensibility, itches me,
Alex
/TJ
-----Original Message----- From: Alexandru Petrescu
[mailto:[EMAIL PROTECTED] Sent: Wednesday, October 01,
2008 12:09 PM To: TJ Cc: 'IETF IPv6 Mailing List' Subject: Re: Why
would anyone want to use a 64 bit interface identifier?
TJ wrote:
I speculate that one possible reason for this was to design a
SLAAC over Ethernet that is reliable, simple, universal and
straightforward to implement.
BINGO. And those are all (IMHO) Good Things.
Well yes, they're Good Things.
In a way, I see SLAAC to have become so popular as opposed to
DHCP. Were DHCPv6 more developed we wouldn't have this
IID-64bit problem, I
think.
We could debate how "popular" SLAAC is (many of those arguments,
both pro and con, are environment / deployment specific), but
more relevant - some DHCP implementations also assume a 64b IID.
I think I agree.
Which aspect is the cart and which is the horse could also be
debated, but the real point is - again - that this assumption has
been baked-in to so many things that changing it is (yes, still
IMHO) a Bad Thing.
Well of course, one wouldn't dare suggest changing such deeply
entrenched std and implementation, bar the deployed base.
However, one can't stop oneself express the strong frustration felt
about extending an IPv6 network. With all the great SLAAC
features and software availability - yet it's hard to extend a
common IPv6 subnet: one needs DHCPv6 prefix delegation be in place,
or one needs to be
allocated
a shorter than /64 prefix (e.g. be allocated a /56). These are
rare.
Thanks for the message, I'll go in listening mode :-)
Alex
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