Default route (IPv4) demolished by destroying clone (gif/gre) interface

[Darryl Yeoh]

On Wed, 16 Aug 2006 11:46:39 +0300 (EEST)
Dmitry Pryanishnikov <dmitry at atlantis.dp.ua> wrote:

> 
> Hello!
> 
> On Wed, 16 Aug 2006, Yar Tikhiy wrote:
> > The question is:  Do all the routes really need to be flushed upon
> > the destruction of an interface?
> 
>   I've killed devd on my test machine (yesterday's RELENG_6) and done
> the following:
> 
> root at test# ifconfig vlan0 create
> root at test# ifconfig vlan0 inet 10.1.1.1/30
> root at test# route add 10.2.2.0/24 10.1.1.1
> add net 10.2.2.0: gateway 10.1.1.1
> root at test# nst -rn
> Routing tables
> Internet:
> Destination        Gateway            Flags    Refs      Use  Netif Expire
> default            193.108.47.145     UGS         0    64439    rl0
> 10.0.0.252/30      link#1             UC          0        0   fxp0
> 10.1.1/30          link#4             UC          0        0  vlan0
> 10.1.1.1           00:00:00:00:00:00  UHLW        2        0    lo0
> 10.2.2/24          10.1.1.1           UGS         0        0  vlan0
> 127.0.0.1          127.0.0.1          UH          0        0    lo0
> 193.108.47.144/29  link#2             UC          0        0    rl0
> 193.108.47.145     00:02:b3:8b:26:4a  UHLW        2    20523    rl0     38
> root at test# ifconfig vlan0 destroy
> root at test# nst -rn
> Routing tables
> Internet:
> Destination        Gateway            Flags    Refs      Use  Netif Expire
> default            193.108.47.145     UGS         0    64500    rl0
> 10.0.0.252/30      link#1             UC          0        0   fxp0
> 127.0.0.1          127.0.0.1          UH          0        0    lo0
> 193.108.47.144/29  link#2             UC          0        0    rl0
> 193.108.47.145     00:02:b3:8b:26:4a  UHLW        2    20571    rl0     58
> 
> So it seems that just simple 'ifconfig vlan0 destroy' already takes care
> about all the routes via the defunct interface, and does this correctly.
> The question is whether interface auto-destruction code in kernel does
> the same. I don't have removable NIC hardware handy to check this.
> 
> Sincerely, Dmitry
> -- 
> Atlantis ISP, System Administrator
> e-mail:  dmitry at atlantis.dp.ua
> nic-hdl: LYNX-RIPE

Hi guys,

Alright, setting removable_route_flush="NO" seems to help for now. Destroying an interface removes
routes associated only to that interface.

"The question is whether interface auto-destruction code in kernel does the same."

I'm curious about this too.

- Darryl Yeoh