Subject: Results: Straw poll: autoconf vs manual conf

From: Brian Dickson <[email-masked]>
Date: Thu, 13 Sep 2007 15:58:50 -0400

[email-masked] wrote:
> (I realize this list might not represent the bulk of the deployed IPv6
> networks... nonetheless, I'm curious.)
>
> This is an informal survey of what is deployed in terms of IPv6 networks.
> Do you use autoconf only, static assignments only, or a mix?
>
>   

Many thanks to those who responded, although the number of responses was
a bit smaller than I expected.

Here's a rough summary of deployed IPv6 networks:

Number of networks represented: in the hundreds
Proportion all-static: << 5%
Proportion all-auto: ~ 30%
Proportion mixed: ~ 60%
Proportion DHCPv6: << 5%

Interestingly, it would appear that even for all-static, there is
forward-thinking support for autoconf.
Notably, even though they consist only of statically configured servers,
the predominant prefix length is /64.

In one case, multiple /64's were in use, where each /64 was on a
different VLAN, and was used to correspond to an IPv4 subnet, with hosts
numbered by the same host-part of the address.

And a substantial number of respondents could be categorized as running
either personal IPv6 networks for hobbyist set-ups, including IPv6 over
IPv4 tunnels, or lots of R&D subnets.

One respondent pointed out that doing reverse DNS is a major pain in any
kind of autoconf universe.

I didn't get the sense that anyone using any of these methods, were
overly concerned with the details under the hood, but mainly seemed
happy that what they had, was working for them.

If anything, I was surprised that both autoconf-only and mixed
(including autoconf) was deployed as widely as it is.

While this concludes the straw poll, the results themselves may lead to
other discussions, notwithstanding the current state of the IPv6 working
group.

Brian Dickson
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From: Bob Hinden <[email-masked]>
Date: Wed, 19 Sep 2007 11:15:43 -0700

> a bit smaller than I expected.

I think the reason for the small number of responses was that you  
never clarified if you were talking about hosts, routers, or both.   
Most people ignored your poll.  For example, on my home network I  
statically configure the router and use autoconfig for all the  
hosts.  It wasn't clear how to answer.

The result of this is that I don't think you can draw any valid  
conclusions from your poll.

Bob

---

From: Brian Dickson <[email-masked]>
Date: Wed, 19 Sep 2007 14:39:24 -0400

> never clarified if you were talking about hosts, routers, or both.
Hmmm....

I never received any requests for clarification, so I don't agree that 
it was confusing.
Do you know of anyone personally that chose not to answer because of this?

I would not have thought anyone uses autoconfig for routers - the 
thought never occurred to me.

As for the poll -  I was talking only of hosts.
> statically configure the router and use autoconfig for all the hosts.  
> It wasn't clear how to answer.
>
Autoconfig. I'll add your answer to the results. :-)
> conclusions from your poll.
Since it is a straw poll, the respondents being self-selecting, the 
conclusions are applicable only to the small sample set.

That is why it is a straw poll - it's only a vague litmus test, not 
anything meant to be conclusive per se.

If you think you'd get more answers, feel free to do a straw poll 
yourself, of course. I'd be interested to see if the results differ 
significantly.

Brian

---

From: Bob Hinden <[email-masked]>
Date: Wed, 19 Sep 2007 13:08:01 -0700

Brian,

> I never received any requests for clarification, so I don't agree  
> that it was confusing.

Yes, right after you sent the poll.  See:

   http://www1.ietf.org/mail-archive/web/ipv6/current/msg08529.html

I thought it was odd you didn't respond.

Bob

---

From: Brian Dickson <[email-masked]>
Date: Wed, 19 Sep 2007 16:40:47 -0400

> I thought it was odd you didn't respond.

Okay, I stand corrected. I got *one* request for a clarification, and it 
was from Illjitsch.
Because of who asked the question and how he asked it, I didn't actually 
think he was asking a serious question.
(Sorry, Illjitsch - no offense intended.)

Nothing stopped him from providing poll responses with the details 
others provided.
Those who weren't sure, described their set-up, and asked me to 
categorize it - which I did in the summary.

Nobody else asked any other questions like that, in spite of numerous 
responses.

Some did ask whether a static router plus hosts all autoconf was mixed 
or autoconf (IMHO that is autoconf, not mixed).

The rationale behind excluding a (static, RA) router from the autoconf 
vs mixed question is, if you subtract the router, autoconf can't work 
since there is no RA.
Any set-up which has an autoconf router hanging off a subnet which has 
another router acting as RA, would still end up classifying the subnet 
as "autoconf".
A set-up where two routers are connected to a broadcast network 
(ethernet, for example), where only one of the routers is the RA for 
that subnet/segment, and the other is *statically* configured on that 
subnet, could be classified either as "mixed", or as "autoconf".

Illjitsch's interface config seemed to me to make his question 
facetious, for just that reason - he only showed a router config, and 
made no references to hosts.

If anyone else want to answer the Straw Poll now, with the clarification 
on this point, I'd be happy to take new answers, and re-summarize....

Brian

---

From: Bob Hinden <[email-masked]>
Date: Wed, 19 Sep 2007 13:53:31 -0700

On Sep 19, 2007, at 1:40 PM, ext Brian Dickson wrote:

> Okay, I stand corrected. I got *one* request for a clarification,  
> and it was from Illjitsch.
> Because of who asked the question and how he asked it, I didn't  
> actually think he was asking a serious question.

I and I suspect others took it as a serious question.  Since you  
didn't answer, I ignored your poll.

Bob

---

From: Brian Dickson <[email-masked]>
Date: Wed, 19 Sep 2007 17:03:52 -0400

Bob Hinden wrote:
>> Okay, I stand corrected. I got *one* request for a clarification, and 
>> it was from Illjitsch.
I didn't answer *yet* as of then, but have answered it now.

Does this mean you'll answer the poll now?

Brian

---

From: Bob Hinden <[email-masked]>
Date: Wed, 19 Sep 2007 14:37:33 -0700

> Does this mean you'll answer the poll now?

Sure, 100% auto-config.

Bob

---

From: Tim Chown <[email-masked]>
Date: Mon, 24 Sep 2007 09:12:08 +0100

> >Does this mean you'll answer the poll now?

I didn't answer orginally because it seems to early to ask the question,
without mature DHCPv6 implentations available.

We use autoconfig for clients, manual config for servers and routers.
We will use DHCPv6 for clients soon.

-- 
Tim

---

From: Alain Durand <[email-masked]>
Date: Fri, 28 Sep 2007 10:01:02 -0400

Coming late into this discussion...

In our deployment which concern a very large number of devices (many
millions), we will use DHCPv6 only.

In our internal infrastructure, we are planning to use mostly DHCPv6 on
servers and manual config for anything where DHCPv6 may not make sense, eg
routers.

0% stateless autoconf.

    - Alain.

---

From: james woodyatt <[email-masked]>
Date: Fri, 28 Sep 2007 09:42:37 -0700

> 0% stateless autoconf.

Do you mean there will be router advertisements with M=1 and one or  
more prefix information options with A=0?

--
james woodyatt <[email-masked]>
member of technical staff, communications engineering

---

From: "DE JUAN HUARTE FEDERICO" <[email-masked]>
Date: Fri, 28 Sep 2007 20:00:35 +0200

Hi,

I apologize for abusing of this thread but I'm looking for a simple answer (if such thing is possible)
If a network administrator decides to set the M bit meaning that it intends to always manage the address configuration, can he expect all hosts to support the DHCP functionality?

In other words, is DHCP a MUST implement for IPv6 hosts?

Regards

federico

-----Message d'origine-----
De : james woodyatt [mailto:[email-masked]] 
Envoyé : vendredi 28 septembre 2007 18:43
À : IPV6 Mailing List
Objet : Re: Results: Straw poll: autoconf vs manual conf

> 0% stateless autoconf.

Do you mean there will be router advertisements with M=1 and one or more prefix information options with A=0?

---

From: james woodyatt <[email-masked]>
Date: Fri, 28 Sep 2007 11:27:44 -0700

> In other words, is DHCP a MUST implement for IPv6 hosts?

Only if they expect to obtain service from the router sending  
advertisements with M=1.  Nodes that don't implement DHCP6 are free  
to obtain service from other routers on the same link.  They're also  
still free to use link-local scope IPv6 on the link.

---

From: Alain Durand <[email-masked]>
Date: Fri, 28 Sep 2007 14:58:16 -0400

On 9/28/07 12:42 PM, "james woodyatt" <[email-masked]> wrote:

> * It will depend. Some places may have just that, some others may have M1 =but
> no prefixes at all include in the RA.

                - Alain.

---

From: james woodyatt <[email-masked]>
Date: Fri, 28 Sep 2007 12:01:17 -0700

On Sep 28, 2007, at 11:49, James Carlson wrote:
>
> And it'd probably take the threat of violence to prevent them from
> using manually-configured addresses (even global scope ones) if they
> so choose.

Or EAPOL.

---

From: Alain Durand <[email-masked]>
Date: Fri, 28 Sep 2007 15:07:50 -0400

Whatever the IETF decides, implementers are free to implement what they want
and network managers are free to deploy what they want the way they want.
Ie, devices that may or may not implement DHCPv6.
Some devices that  have DHCPv6 implemented could be configured to ignore
completely the M bit and do what they have been told to do through other
configuration means.
In some cases, they will ignore M=1 and just do manual config for exemple,
in others they will try DHCPv6 even if M=0.

   - Alain.

---

From: James Carlson <[email-masked]>
Date: Fri, 28 Sep 2007 14:49:31 -0400

-- 
James Carlson, Solaris Networking              <[email-masked]>
Sun Microsystems / 35 Network Drive        71.232W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 781 442 1677

---

From: Basavaraj Patil <[email-masked]>
Date: Fri, 28 Sep 2007 14:14:37 -0500

Alain,

In your deployment, you probably control the host as well and hence can
choose DHCPv6 as the only mechanism for address assignment. This works fine
in such an environment. But not in an environment where many different types
of hosts with different capabilities could attach to the network.

Is there a logical argument for not allowing hosts to configure addresses
via SLAAC? 

-Raj

---

From: Brian Haberman <[email-masked]>
Date: Fri, 28 Sep 2007 14:41:47 -0400

DE JUAN HUARTE FEDERICO wrote:
> Hi,
> 
> I apologize for abusing of this thread but I'm looking for a simple
> answer (if such thing is possible) If a network administrator decides
> to set the M bit meaning that it intends to always manage the address
> configuration, can he expect all hosts to support the DHCP
> functionality?
> 

The IPv6 Node Requirements document (RFC 4294) has the following text 
related to DHCPv6:

    The method by which IPv6 nodes that use DHCP for address assignment
    can obtain IPv6 addresses and other configuration information upon
    receipt of a Router Advertisement with the 'M' flag set is described
    in Section 5.5.3 of RFC 2462.

    In addition, in the absence of a router, those IPv6 nodes that use
    DHCP for address assignment MUST initiate DHCP to obtain IPv6
    addresses and other configuration information, as described in
    Section 5.5.2 of RFC 2462.  Those IPv6 nodes that do not use DHCP for
    address assignment can ignore the 'M' flag in Router Advertisements.

Regards,
Brian

---

From: Basavaraj Patil <[email-masked]>
Date: Fri, 28 Sep 2007 14:14:37 -0500

Alain,

-Raj

---

From: Brian Haberman <[email-masked]>
Date: Fri, 28 Sep 2007 14:41:47 -0400

Regards,
Brian

---

From: Iljitsch van Beijnum <[email-masked]>
Date: Sat, 29 Sep 2007 02:01:04 +0200

On 28-sep-2007, at 20:00, DE JUAN HUARTE FEDERICO wrote:

> If a network administrator decides to set the M bit meaning that it  
> intends to always manage the address configuration, can he expect  
> all hosts to support the DHCP functionality?

> In other words, is DHCP a MUST implement for IPv6 hosts?

Note that these are separate questions. The latter has already been  
answered.

As to the former: no, it's certainly not true that all hosts support  
DHCP. And the ones that do, may support one, two or three of the  
following capabilities:

- other configuration (such as DNS server addresses)
- prefix delegation
- address assignment

I would be interested in hearing about anyone actually using DHCPv6  
address assignment. Two years ago when I wrote my book about IPv6 I  
couldn't find any servers or clients that supported this. I gather  
this has changed, but I'm not sure to what degree.

---

From: "Bernie Volz \(volz\)" <[email-masked]>
Date: Fri, 28 Sep 2007 23:29:15 -0400

Cisco has been shipping DHCPv6 server support in Cisco Network Registrar
since January 2006. It supports stateless, stateful, and PD.

And, of course we have various degrees of DHCPv6 support in IOS (relay,
PD client/server) depending on the release.

- Bernie

---

From: Brian Dickson <[email-masked]>
Date: Sat, 29 Sep 2007 02:18:34 -0400

> millions), we will use DHCPv6 only.
Thanks for your answer, it certainly adds much to the poll results. (!!)

Would you mind a few follow-up questions, on the DHCPv6 set-up you 
described? I'm sure I'm not alone in being interested in the details...

Will each CPE device's "clients", i.e. customer hosts, be directly 
assigned addresses, with the CPE acting as a relay? And thus hosts in 
one head-end receive assignments from a prefix on a first-come, first 
serve basis?

Or, will the CPE be delegated prefix(es), and hosts given addresses out 
of the appropriate delegated prefix?

What prefix length(s) will be in use, typically?

How are addresses assigned and/or constructed? Does client MAC get used 
directly (EUI-48) or indirectly (EUI-64) or not at all?

Is there anything related to DHCPv6 that your set-up either supposes, or 
supports, related to prefix delegation to customer-operated CPE devices, 
like stateful firewalls?
(I'm thinking (cloud)->CPE docsis3.0 modem -> stateful firewall -> (N * 
customer devices).)

BTW - I'm not trying to question your network design or implementation, 
or anything remotely similar.

I'm only trying to understand whether anything from DHCPv6 is in any way 
limited in what kind of prefixes it can use, or whether anything is 
steering you towards specific prefix length(s).

Any light you can shed, as far as implications on prefix-length vs 
DHCPv6 is concerned, would be appreciated.

The reason I ask is, I'm working on stuff to address prefix-length 
issues related to autoconfiguration.
Given the number of clients you are talking about, I think I need to be 
sure any relevant DHCPv6 stuff gets handled too.

Thanks,

Brian

---

From: Ralph Droms <[email-masked]>
Date: Sat, 29 Sep 2007 21:27:43 -0400

Cisco has had DHCPv6 (client, server and relay agent) in IOS since  
2003.  The first TAHI DHCPv6 testing was also in 2003.  Results from  
the interoperability testing of several servers and clients was used  
to improve the DHCPv6 spec (RFC 3315), published in July 2003.  The  
dibbler project DHCPv6 client and server have been available for  
several years, as well.

- Ralph

On Sep 28, 2007, at Sep 28, 2007,8:01 PM, Iljitsch van Beijnum wrote:

>> If a network administrator decides to set the M bit meaning that  
>> it intends to always manage the address configuration, can he  
>> expect all hosts to support the DHCP functionality?
>
> As to the former: no, it's certainly not true that all hosts  
> support DHCP. And the ones that do, may support one, two or three  
> of the following capabilities:
>