Re: [v6ops] New Version Notification for draft-ipversion6-loopback-prefix-00.txt

[Mark ZZZ Smith <[e-mail]>]

________________________________
From: Mark Andrews <[e-mail]>
To: Mark ZZZ Smith <[e-mail]> 
Cc: David Conrad <[e-mail]>; "[e-mail]" <[e-mail]> 
Sent: Tuesday, 17 February 2015, 12:23
Subject: Re: [v6ops] New Version Notification for draft-ipversion6-loopback-prefix-00.txt



The fundemental reason for 127.0.0.0/8 was to give each node a
addresses block they could use. 127.0.0.1 evolved as the "standard"
loopback address over time.

/ Actually, 4.2BSD made added the '.1' as the default address, as the '0' they'd originally chosen was the BSD broadcast address:

http://minnie.tuhs.org/cgi-bin/utree.pl?file=4.2BSD/usr/src/sys/netinet/if_loop.c



 For the most part no one uses the rest
of 127.0.0.0/8 but it is useful to have available.

/ I'm not sure I completely agree with the idea, however the NTP reference clock drivers use 127.127/16 addresses to make them available to the ntp daemon. I think this use is a bit different to what ICANN specified, as those addresses only have local significance on the host that both the ntp daemon and the reference clocks are attached to. Outside of that host they're unreachable and have no meaning. Fortunately with millions of other addresses within 127/8 there are plenty of others to use for other purposes on the host.

 
That said any
use of the rest of 127.0.0.0/8 has to be negotiated between the
users.  You can't just grab 127.0.0.2 and hope that no one else is
using it for IP traffic.


/ I'm a bit confused by this. 127.0.0.2 traffic should not be leaking outside of the host, as that is contrary to RFC990/RFC1122 rules. So the only risk of collision is two users on the same host. That is of course possible, however the great thing is that there are millions of other loopback addresses available on the host that the users can choose from, and the ones in use can be viewed with 'netstat -a -4 -n' or similar. Hosts have become pretty much single user too these days.

/ ::1/128 is pretty much single user use.

In IPv6 we had both link local and site local addresses from the
get go.  These gave the operator addresses they could use.  They
were also slightly more complicated than a GUA as you needed to
specify scope.  We now have ULA addresses which gets rid of the
need to specify scope.  Just like with 127.0.0.2 you need to negotiate
the use of a address.

Reserving a new block of addressing in IPv6 will not stop the need
to negotiate address use.

If you need truly automatic assignment you need to go to IANA or a
RIR (e.g. ARIN and 100.64/10) and request a block for a specific

purpose.  There is no other way to do truly automatic.

/ From my draft:

"9.  IANA Considerations

IANA is requested to allocate 0001::/32 from within 0000::/8 of the
Internet Protocol Version 6 Address Space, for use as a larger
loopback prefix for IPv6, as detailed in this memo, and to record it
in the [IANA-IPV6REG]."


Mark

In message <[e-mail]>, Mar
k ZZZ Smith writes:
> So the fundamental problem is 'configured like this'. It's a manual operation
>  to generate and apply a ULA. ULAs on loopbacks aren't going to well known or
>  ubiquitous.
> 
> If you want something to be used you need to make it easy, and the best way t
> o make something easy is to make it automatic.
> 
> The value in 127/8, ::1 and a larger IPv6 loopback prefix is that it is or wo
> uld be automatically configured by the OS, with operator intervention. It's a
> lways there, and always available to use. The 4.1c/2.9BSD people though there
>  was value in automatic configuration of the loopback address on a loopback i
> nterface, way back in 1982/1983:
> 
> http://minnie.tuhs.org/cgi-bin/utree.pl?file=2.9BSD/usr/net/sys/net/if_loop.c
> 
> http://minnie.tuhs.org/cgi-bin/utree.pl?file=4.1cBSD/a/sys/netinet/if_loop.c
> 
> 
> 
> ----- Original Message -----
> From: Mark Andrews <[e-mail]>
> To: David Conrad <[e-mail]>
> Cc: Mark ZZZ Smith <[e-mail]>; "[e-mail]" <v6ops@ietf.
> org>
> Sent: Tuesday, 17 February 2015, 10:22
> Subject: Re: [v6ops] New Version Notification for draft-ipversion6-loopback-p
> refix-00.txt
> 
> 
> We don't need *more* reserved address for this.  This is from my
> laptop and it has been configured like this for years.
> 
> Yes, I have a ULA site on my loopback interface.  If your loopback
> interface does not support this it is broken.
> 
> 
> Mark
> 
> lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
>     options=3<RXCSUM,TXCSUM>
>     inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1 
>     inet 127.0.0.1 netmask 0xff000000 
>     inet6 ::1 prefixlen 128 
>     inet 10.53.0.1 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::1 prefixlen 64 
>     inet 10.53.0.2 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::2 prefixlen 64 
>     inet 10.53.0.3 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::3 prefixlen 64 
>     inet 10.53.0.4 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::4 prefixlen 64 
>     inet 10.53.0.5 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::5 prefixlen 64 
>     inet 10.53.0.6 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::6 prefixlen 64 
>     inet 10.53.0.7 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::7 prefixlen 64 
>     inet 10.53.0.8 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::8 prefixlen 64 
>     inet 10.53.0.9 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::9 prefixlen 64 
>     inet 10.53.0.10 netmask 0xffffffff 
>     inet6 fd92:7065:b8e:ffff::10 prefixlen 64 
> 
> -- 
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: [phone]                 INTERNET: [e-mail]



-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: [phone]                 INTERNET: [e-mail]