Subject: Fwd: New Version Notification for draft-petrescu-6man-ll-prefix-len-08.txt

From: Alexandre Petrescu <[email-masked]>
Date: Wed, 17 Apr 2019 14:18:12 +0200

Hello to participants in 6MAN,

I am looking for co-authors.

I have just submitted a new version of the individual proposal draft 
about the prefix length of link local addresses.

The new version is -08.

This is the ChangeLog:

- added explanation of which RFC requires the LL address to be
    present, and which requires the LL prefix to be present;

- named the  OSs, instead of staying generic;

- explained that the lack of   requirement of ll address on lo in 
RFC4291 is covered by another
    RFC4007;

- explained that openbsd allows variable len IID for GUAs but not for 
LLs, yet linux allows the reverse, and concluded on an
    obvious ideal.

Alex

-------- Message transféré --------
Sujet : 	New Version Notification for 
draft-petrescu-6man-ll-prefix-len-08.txt
Date : 	Wed, 17 Apr 2019 05:15:06 -0700
De : 	[email-masked]
Pour : 	Alexandre Petrescu <[email-masked]>, Alexandre 
Petrescu <[email-masked]>

A new version of I-D, draft-petrescu-6man-ll-prefix-len-08.txt
has been successfully submitted by Alexandre Petrescu and posted to the
IETF repository.

Name: draft-petrescu-6man-ll-prefix-len
Revision: 08
Title: The length of the prefix of an IPv6 link-local address ranges 
from 10 to 127
Document date: 2019-04-17
Group: Individual Submission
Pages: 7
URL: 
https://www.ietf.org/internet-drafts/draft-petrescu-6man-ll-prefix-len-08.txt
Status: https://datatracker.ietf.org/doc/draft-petrescu-6man-ll-prefix-len/
Htmlized: https://tools.ietf.org/html/draft-petrescu-6man-ll-prefix-len-08
Htmlized: 
https://datatracker.ietf.org/doc/html/draft-petrescu-6man-ll-prefix-len
Diff: https://www.ietf.org/rfcdiff?url2=draft-petrescu-6man-ll-prefix-len-08

Abstract:
A rejected Errata to RFC4291 "IPv6 Addr Archi" on the topic of link-
local addresses 'needs' a draft. This is an answer to that need.

The length of the prefix of an IPv6 link-local address is variable.
The minimal value is 10 decimal. The maximum value is 127 decimal.

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

The IETF Secretariat

---

From: Gyan Mishra <[email-masked]>
Date: Wed, 17 Apr 2019 21:44:46 -0400

I agree with the updated revision comments posted and that all OSs and that they should be specific of which OS all inclusive including all flavors of Linux should require LL to be present and also require and adhere to the LL format standard if the LL is changed to not using the default EUI formatted LL and if changed should require the prefix that is changed must be within the 64 bit network field per the LL RFC.

Gyan S. Mishra
IT Network Engineering & Technology Consultant
Routing & Switching / Service Provider MPLS & IPv6 Expert
www.linkedin.com/in/GYAN-MISHRA-RS-SP-MPLS-IPV6-EXPERT
Mobile – 202-734-1000

Sent from my iPhone

> On Apr 17, 2019, at 8:18 AM, Alexandre Petrescu <[email-masked]> wrote:
> 
> I have just submitted a new version of the individual proposal draft about the prefix length of link local addresses.
> 
> The new version is -08.
> 
> This is the ChangeLog:
> 
> - explained that the lack of   requirement of ll address on lo in RFC4291 is covered by another
>    RFC4007; 
> 
> - explained that openbsd allows variable len IID for GUAs but not for LLs, yet linux allows the reverse, and concluded on an
>    obvious ideal.
> 
> Alex
> 
> 
> 
> Sujet :	New Version Notification for draft-petrescu-6man-ll-prefix-len-08.txt
> Pour :	Alexandre Petrescu <[email-masked]>, Alexandre Petrescu <[email-masked]>
> 
> 
> 
> Title: The length of the prefix of an IPv6 link-local address ranges from 10 to 127
> URL: https://www.ietf.org/internet-drafts/draft-petrescu-6man-ll-prefix-len-08.txt
> Htmlized: https://datatracker.ietf.org/doc/html/draft-petrescu-6man-ll-prefix-len
> --------------------------------------------------------------------
> IETF IPv6 working group mailing list
> [email-masked]
> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
> --------------------------------------------------------------------

---

From: Alexandre Petrescu <[email-masked]>
Date: Thu, 18 Apr 2019 11:07:07 +0200

iPhone writing is great, but le'me try to separate it in tokens that I 
believe represent your ideas.

Le 18/04/2019 à 03:44, Gyan Mishra a écrit :
> I agree with the updated revision comments posted

Thank you for the agreement.

> and that all OSs and that they should be specific of which OS all
> inclusive including

> all flavors of Linux should require LL to be present

YEs, they do, as far as I know.  All OSs and all kinds of IP-over-foo 
interfaces like Ethernet, 15.4, USB and cellular: each has an ll address.

Some loopback interfaces in linux dont have ll address.

> and also require and adhere to the LL format standard

It's easy to require, but do we know what is an LL format standard?

For me, the LL is an address above all.  While in English we say 
"link-local address" and tend to think it is link-local first, in French 
we say "adresse lien-locale" and thus is an address first.

Then, after being an address, it has a scope.  The scope is in the first 
10 bits.

Then, there is a prefix and finally an Interface ID.

That is my definition of an LL address format standard.

Other explainers surprised me.  To them, the LL address is like I also 
think it, but the kernel programmer must be allowed to encode a Zone ID 
into the 54 intermediary bits of the data structure containing the 
link-local address, even though command-line user does not see this Zone 
ID in the address.

I think that should be possible (to use the 54bits as a place for Zone 
ID) but only as long as this use does not hurt the feeling of what an 
address is.

On another hand, other person seems to think that it should be possible 
to use Zone ID within the LL, in a hidden manner, but only as long as 
the 54bits stay always at 0.

That is a conflict.   Things break.

FOr example, in linux you can type "ifconfig eth0 add fe80:1::1" and it 
succeeds; but linux has no Zone ID.  On another hand, typing on FreeBSD 
"ifconfig re0 inet6 fe80:1::1 prefixlen 128" will not succeed.

That is a problem.

> if the LL is changed to not using the default EUI formatted LL and if
> changed should require the prefix that is changed must be within the
> 64 bit network field per the LL RFC.

Err, but how about the link-local address on loopback interface?

On BSD the ll address on lo is fe80::1.  That is not EUI-64.  The plen 
is 128, not 64.

On linux there is no fe80::1 on lo.

 > per the LL RFC.

What is the LL RFC?

Alex

> 
> Gyan S. Mishra IT Network Engineering & Technology Consultant Routing
> & Switching / Service Provider MPLS & IPv6 Expert 
> <http://www.linkedin.com/in/GYAN-MISHRA-RS-SP-MPLS-IPV6-EXPERT> 
> Mobile – 202-734-1000 <tel:202-734-1000>
> 
> Sent from my iPhone
> 
> On Apr 17, 2019, at 8:18 AM, Alexandre Petrescu 
> <[email-masked] <mailto:[email-masked]>>
> wrote:
> 
>> I have just submitted a new version of the individual proposal
>> draft about the prefix length of link local addresses.
>> 
>> The new version is -08.
>> 
>> This is the ChangeLog:
>> 
>> RFC4291 is covered by another RFC4007;
>> 
>> - explained that openbsd allows variable len IID for GUAs but not
>> for LLs, yet linux allows the reverse, and concluded on an obvious
>> ideal.
>> 
>> Alex
>> 
>> 
>> 
>> -------- Message transféré -------- Sujet : 	New Version
>> Notification for draft-petrescu-6man-ll-prefix-len-08.txt Date :
>> Wed, 17 Apr 2019 05:15:06 -0700 De : 	[email-masked] Pour
>> : 	Alexandre Petrescu <[email-masked]>, Alexandre 
>> A new version of I-D, draft-petrescu-6man-ll-prefix-len-08.txt has
>> been successfully submitted by Alexandre Petrescu and posted to
>> the IETF repository.
>> 
>> Name: draft-petrescu-6man-ll-prefix-len Revision: 08 Title: The
>> length of the prefix of an IPv6 link-local address ranges from 10
>> to 127 Document date: 2019-04-17 Group: Individual Submission 
>> Pages: 7 URL: 
Status:
>> https://datatracker.ietf.org/doc/draft-petrescu-6man-ll-prefix-len/
>>
>> 
Diff:
>> https://www.ietf.org/rfcdiff?url2=draft-petrescu-6man-ll-prefix-len-08
>>
>>
>> 
Abstract:
>> A rejected Errata to RFC4291 "IPv6 Addr Archi" on the topic of
>> link- local addresses 'needs' a draft. This is an answer to that
>> need.
>> 
>> The length of the prefix of an IPv6 link-local address is
>> variable. The minimal value is 10 decimal. The maximum value is 127
>> decimal.
>> 
>> 
>> 
>> Please note that it may take a couple of minutes from the time of 
>> submission until the htmlized version and diff are available at
>> tools.ietf.org <http://tools.ietf.org>.
>> 
>> The IETF Secretariat
>> 
>> [email-masked] <mailto:[email-masked]> Administrative Requests:
>> https://www.ietf.org/mailman/listinfo/ipv6

---

From: Gyan Mishra <[email-masked]>
Date: Thu, 18 Apr 2019 12:23:48 -0400

Thanks Alex

I was referring to the IPv6 RFC  3513 that goes over the address format of
the Link Local address.

I agree that the LL address if modified the prefix length for the LL should
be maximum of 64 bits and not bleed into the station id portion larger
prefix length then 64 bits.

2.5.6 <https://tools.ietf.org/html/rfc3513#section-2.5.6> Local-Use
IPv6 Unicast Addresses

   There are two types of local-use unicast addresses defined.  These
   are Link-Local and Site-Local.  The Link-Local is for use on a single
   link and the Site-Local is for use in a single site.  Link-Local
   addresses have the following format:

   |   10     |
   |  bits    |         54 bits         |          64 bits           |
   +----------+-------------------------+----------------------------+
   |1111111010|           0             |       interface ID         |
   +----------+-------------------------+----------------------------+

   Link-Local addresses are designed to be used for addressing on a
   single link for purposes such as automatic address configuration,
   neighbor discovery, or when no routers are present.

   Routers must not forward any packets with link-local source or
   destination addresses to other links.

   Site-Local addresses have the following format:

   |   10     |
   |  bits    |         54 bits         |         64 bits            |
   +----------+-------------------------+----------------------------+
   |1111111011|        subnet ID        |       interface ID         |
   +----------+-------------------------+----------------------------+

   Site-local addresses are designed to be used for addressing inside of
   a site without the need for a global prefix.  Although a subnet ID
   may be up to 54-bits long, it is expected that globally-connected
   sites will use the same subnet IDs for site-local and global
   prefixes.

   Routers must not forward any packets with site-local source or
   destination addresses outside of the site.

Gyan S. Mishra

-- 
Gyan S. Mishra