kern/188032: IPv6 on lo never leaves 'tentative' state if configured with prefixlen 128

[Darren Baginski]

The following reply was made to PR kern/188032; it has been noted by GNATS.

From: Darren Baginski <kickbsd at yandex.ru>
To: Andrey V. Elsukov <bu7cher at yandex.ru>,
	"freebsd-gnats-submit at FreeBSD.org" <freebsd-gnats-submit at freebsd.org>
Cc:  
Subject: Re: kern/188032: IPv6 on lo never leaves 'tentative' state if configured with prefixlen 128
Date: Thu, 03 Apr 2014 05:08:45 +0400

 31.03.2014, 12:11, "Andrey V. Elsukov" <bu7cher at yandex.ru>:
 >> šIPv6 on lo never leaves 'tentative' state if configured with prefixlen 128.
 >>
 >> šSteps to reproduce.
 >>
 >> š# ifconfig lo8 create
 >> š# ifconfig lo8 up
 >> š# ifconfig lo8 inet6 fc00::ff prefixlen 128
 >>
 >> š# ifconfig lo8
 >> šlo8: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
 >> šššššššššoptions=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
 >> šššššššššinet6 fc00::ff prefixlen 128 tentative
 >> šššššššššnd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
 >>
 >> šlo8 ipv6 stays 'tentative' stays forever and never become ping-able.
 >>
 >> š"Workaround" is to apply any other prefixlen, e.g. /127
 >>> šHow-To-Repeat:
 >> š# ifconfig lo8 create
 >> š# ifconfig lo8 up
 >> š# ifconfig lo8 inet6 fc00::ff prefixlen 128
 >>
 >> š# ifconfig lo8
 >> šlo8: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
 >> šššššššššoptions=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6>
 >> šššššššššinet6 fc00::ff prefixlen 128 tentative
 >> šššššššššnd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
 >>
 >> š# ping fc00::ff
 >>> šFix:
 >> š"Workaround" is to apply any other prefixlen, e.g. /127
 >
 > Hello,
 >
 > Actually the problem is in your configuration. As you may see, you have
 > IFDISABLED flag set. When you are configuring /127 prefix, the system
 > does install route on that prefix and automatically clears IFDISABLED
 > flag. When you are configuring /128 prefix, the system won't install
 > route and thus IFDISABLED flag still here. With IFDISABLED flag the
 > system won't do DAD and štentative flag will never cleared.
 >
 > --
 > WBR, Andrey V. Elsukov
 
 I'm not setting IFDISABLED flag as you see from output below.
 Moreover the same set of commands doesn't dot put interface into IFDISABLED sate on FreeBSD 7.x, 8.x, 9.x
 Again, if I set IPv4 /32 it works as well. 
 Thus this /128 case is a clear regression.