Incorrect handling of primary/secondary IP address status.

[Ondrej Zajicek]

On Fri, Dec 17, 2021 at 05:41:40PM +0100, Alexander wrote:
> Hi,
> 
> Looks like bird (2.0.8 on Linux) incorrectly handles primary/secondary IP
> address status.
> 
> For example, this is initial state (output from "show interfaces"):
> 
> enp6s20 up (index=2 master=switch)
>         MultiAccess Broadcast Multicast AdminUp LinkUp MTU=1500
>         192.168.111.1/24 (Preferred, scope site)
>         192.168.111.2/24 (Secondary, scope site)
> 
> Then I remove 192.168.1.2/24, 192.168.111.2/24 promoted to primary
> (promote_secondaries is enabled on interface), but bird does not get it:
> 
> enp6s20 up (index=2 master=switch)
>         MultiAccess Broadcast Multicast AdminUp LinkUp MTU=1500
>         192.168.111.2/24 (Secondary, scope site)
> ... while it is actually primary now:
> 
> 2: enp6s20: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc
> pfifo_fast master switch state UP group default qlen 1000
>     link/ether xx:xx:xx:xx:xx:68 brd ff:ff:ff:ff:ff:ff permaddr
> xx:xx:xx:xx:xx:30
>     inet 192.168.111.2/24 scope global enp6s20
>        valid_lft forever preferred_lft forever

Hi

That is interesting. If i remember correctly, in the past Linux removed
all secondary addresses (ones from the same net) when the primary address
was removed (so only addresses from other networks were considered relevant).

Note that BIRD only selects 'preferred' address (one IP per iface,
BIRD-specific designation), but does not decide whether an address
is secondary or primary/regular (that is reported by Linux kernel in
notifications). So it is possible that Linux promotes an address to
primary, but does not sent a notification about that. Will check that.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3, wwwkeys.pgp.net)
"To err is human -- to blame it on a computer is even more so."