Re: about violation of standards

[Gyan Mishra <[e-mail]>]

...this is also from one of my earlier posts at a desperate hope to put
this discussion about allowing fe80:1::1 and having a consensus agreement
by all that it is not allowed per RED 4291.


One other comment I would like to make as far as standard and that we
should not allow the OS Unix or Windows or any network operating system
drive or change the standards.

Here is the case and point.

Cisco routers for example most all platforms these days use a Linux BSD
kernel so is similar to a standalone Linux flavor server.

What I have noticed and confirmed and this is from extensive IPv6 testing
is that the OS for IPv4 has the capability to do subnet and mask check for
valid IPv4 address coded however IPv6 due to the complexity of IPv6 with
128 bits a subnet check is done and will spit out error for router anycast
if used but major loophole exists and that is that you can configure any
global unicast address in the network 64 bit portion that is not valid and
same goes for Link local addresses.

I believe that is due the coding checks limitations within the OS to check
against what is valid and what is not is so complex to code that OS allows
anything to be configured even though from an IETF RFC perspective it’s not
following the standard IPv6 format.

For example for my CCIE studies I would always code my v6 marching v4 so v4
is let’s say 10.0.0.1/30 I would make my v6 address 10::1/126.

That being said the fe80:1::1 can be coded on both Linux host and a CISCO
router with Linux kernel under the hood but that does not make it correct
or valid that we should now change the RFC 4291 to allow that to happen.

I don’t see any justification to allowing the 54 bits in the network 64 bit
portion of the link local address to be changed from all 0s.

Please respond back to this email thread if you feel differently and also
respond if you agree.



On Mon, Apr 22, 2019, 8:00 PM Gyan Mishra <[e-mail]> wrote:

> I honestly cannot believe that we have been discussing or even
> entertaining discussing this topic.
>
> The IPv6 WG was developed to define standards and not think of ways of
> loopholes to violate the rules of the standard that have been developed and
> especially that have been the standard for decades.  Absolutely absurd!!!
>
> BELOW IS MY EARLIER POST
>
> WE SHOULD NOT AT ALL COSTS VIOLATE RFC 4291!!!!!!!!!!!!!!!!!!!!!
>
> There are many implementations worldwide that I have been involved in
> deployment of IPv6 using a standard architecture that I deploy to all my
> customers and that involves setting the station id on the link local
> address so that the next hop is more intuitive and easily recognizable that
> it’s your local next hop since by default all routers and hosts set the
> station id to EUI64 format FFFE big stuff into the MAC address between the
> 3rd and 4th octet which is “non intuitive”
>
> So the IPv6 addressing RFC 4291 states the 1st 10 bits used for fe80 and
> the next 54 bits must be set to 0 which covers the 64 bit prefix length so
> the entire station id 64 bits is open to be modified and changed as the end
> user desires on any platform and that is following the current RFC
> standard.
>
> So in Alexandre scenario with BSD setting the LL to FE80::1 would be fine
> but if you did fe80:1::1 that would be setting 1s in the all 0s 54 bit
> field of the station id which is not allowed.
>
> So as far a variable link local address I am in favor of variable and you
> have the entire 64 bit station id to modify which is fine but I am
> completely not in favor of violating the current standard of writing into
> the 54 bit all 0s portion of the network prefix.
>
> 2.5.6.  Link-Local IPv6 Unicast Addresses
>    Link-Local addresses are for use on a single link.  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.
>
> On Mon, Apr 22, 2019, 6:04 PM Nick Hilliard <[e-mail]> wrote:
>
>> Alexandre Petrescu wrote on 22/04/2019 20:38:
>> > I would like to add something else: the implementation that does _not_
>> > allow the users to add fe80:1::1 (BSD) does not complain about it.  It
>> > silently refuses.
>>
>> this is expected behaviour on BSD (Kame derivatives?). fe80::/10
>> configuration is controlled by the "ifconfig XX auto_linklocal"
>> directive.  If auto_linklocal is configured, then the kernel will
>> automatically configure the fe80::/64 prefix.  You cannot configure the
>> value directly.
>>
>> Nick
>>
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>