[LARTC] Possible kernel bug with routes

[LARTC] Possible kernel bug with routes

[Sven Anders]

[-- Attachment #1: Type: text/plain, Size: 3295 bytes --]

Hello!

I have a problem with a duplicate route entry, when using a pre-installed route
and automatic take-over by the "heartbeat" daemon, which adds an address and
the kernel adds an route automatically.

PLEASE!!! Can anybody try this yourself and give me an explanation!
I think this a kernel bug...


> ip addr
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    inet 127.0.0.1/8 scope host lo
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1514 qdisc pfifo_fast qlen 1000
    inet 10.10.20.100/32 scope global eth0
> ip route
127.0.0.0 dev lo  scope link
10.10.20.0/24 dev eth0  scope link
default via 10.10.20.1 dev eth0

-- Now I add a route for my ha net:

> ip route add 10.100.0.0/24 dev eth0 proto kernel scope link
> ip route
127.0.0.0 dev lo  scope link
10.10.20.0/24 dev eth0  scope link
10.100.0.0/24 dev eth0  proto kernel  scope link
default via 10.10.20.1 dev eth0

-- The 'heartbeat' will add an address on switch-over:
> ip addr add 10.100.0.1/24 brd 10.100.0.255 dev eth0
ip addr
1: lo: <LOOPBACK,UP> mtu 16436 qdisc noqueue
    inet 127.0.0.1/8 scope host lo
2: eth0: <BROADCAST,MULTICAST,UP> mtu 1514 qdisc pfifo_fast qlen 1000
    inet 10.10.20.100/32 scope global eth0
    inet 10.100.0.1/24 brd 10.100.0.255 scope global eth0
> ip route
127.0.0.0 dev lo  scope link
10.10.20.0/24 dev eth0  scope link
10.100.0.0/24 dev eth0  proto kernel  scope link
10.100.0.0/24 dev eth0  proto kernel  scope link  src 10.100.0.1
default via 10.10.20.1 dev eth0

My question is:
 Why did the kernel add a duplicate routing entry, shouldn't it notice the
 existance and avoid this??
 Is this a bug of the kernel?


| "Radoslaw Horodniczy" answered:
|
| This is not a bug, as you see there are 2 different routes


Ok, then try this:

> ip route del 10.100.0.0/24 dev eth0  proto kernel  scope link
> ip route
127.0.0.0 dev lo  scope link
10.10.20.0/24 dev eth0  scope link
10.100.0.0/24 dev eth0  proto kernel  scope link  src 10.100.0.1
default via 10.10.20.1 dev eth0

Now I removed my manually set route. It succeeds.

If I then try to readd it, it fails. But why?

> ip route add 10.100.0.0/24 dev eth0 proto kernel scope link
RTNETLINK answers: File exists

I thought they are different!?!
Is here any difference I did not see?
If they are not different, why does the kernel not recognize it
(see above) and avoid the duplicate entry?

--------

Another question:

 Why can't I set a route on an interface that is down?
 I can set an address, so why not a route?
 I there a reason for that?
 As far as I understand routing should be handled independed from
 the addresses...

Example:
> ip link set down dev eth0
> ip addr add 10.100.0.1/24 dev eth0
> ip route add 10.100.0.0/24 dev eth0  proto kernel  scope link
RTNETLINK answers: Network is down

--------

PS: I'm running Linux 2.6.15.1
PPS: Why is ANYBODY still ignoring this e-mail for over 3 weeks?????

Regards
 Sven Anders

-- 
 Sven Anders <anders@anduras.de>                 () Ascii Ribbon Campaign
                                                 /\ Support plain text e-mail
 ANDURAS service solutions AG
 Innstraße 71 - 94036 Passau - Germany
 Web: www.anduras.de - Tel: +49 (0)851-4 90 50-0 - Fax: +49 (0)851-4 90 50-55

[-- Attachment #2: anders.vcf --]
[-- Type: text/x-vcard, Size: 339 bytes --]

begin:vcard
fn:Sven Anders
n:Anders;Sven
org:ANDURAS AG;Research and Development
adr;quoted-printable:;;Innstra=C3=9Fe 71;Passau;Bavaria;94036;Germany
email;internet:anders@anduras.de
title:Dipl. Inf.
tel;work:++49 (0)851 / 490 50 - 0
tel;fax:+49 (0)851 / 4 90 50 - 55
x-mozilla-html:FALSE
url:http://www.anduras.de
version:2.1
end:vcard


[-- Attachment #3: Type: text/plain, Size: 143 bytes --]

_______________________________________________
LARTC mailing list
LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc

Re: [LARTC] Possible kernel bug with routes

[Ard van Breemen]

On Mon, Mar 27, 2006 at 11:56:52AM +0200, Sven Anders wrote:
<snipped a lot>
> > ip route add 10.100.0.0/24 dev eth0 proto kernel scope link
> RTNETLINK answers: File exists

s/add/append/

> I thought they are different!?!
> Is here any difference I did not see?
> If they are not different, why does the kernel not recognize it
> (see above) and avoid the duplicate entry?

add prevents duplicates, append just adds.

> Another question:
> 
>  Why can't I set a route on an interface that is down?

That's by some design. Use patches from linuxvirtualserver.org if
you want them to exist.

>  I can set an address, so why not a route?

You don't set an address... The address exists only at the moment
the interface comes up. Before that you don't have the address
(active in your ip stack)

>  I there a reason for that?
>  As far as I understand routing should be handled independed from
>  the addresses...
Jups

> Example:
> > ip link set down dev eth0
> > ip addr add 10.100.0.1/24 dev eth0
> > ip route add 10.100.0.0/24 dev eth0  proto kernel  scope link
> RTNETLINK answers: Network is down

The ip is not there yet.
ip link set up dev eth0           # Activate interfaces
ip a add 127.0.0.1/32 dev eth0    # Bind interface to ipv4 stack
ip a add 10.100.0.1/32 dev lo     # We need a public ip on our ip stack
# Add the route to the interface with sane src ip.
ip route add 10.100.0.0/24 dev eth0 src 10.100.0.1

> PPS: Why is ANYBODY still ignoring this e-mail for over 3 weeks?????

People are busy :-)
_______________________________________________
LARTC mailing list
LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc

Re: [LARTC] Possible kernel bug with routes

[Sven Anders]

[-- Attachment #1: Type: text/plain, Size: 1528 bytes --]


First of all: Thanks for the answer!!!!

Ard van Breemen schrieb:
> On Mon, Mar 27, 2006 at 11:56:52AM +0200, Sven Anders wrote:
> <snipped a lot>
>>> ip route add 10.100.0.0/24 dev eth0 proto kernel scope link
>> RTNETLINK answers: File exists
> 
> s/add/append/
> 
>> I thought they are different!?!
>> Is here any difference I did not see?
>> If they are not different, why does the kernel not recognize it
>> (see above) and avoid the duplicate entry?
> 
> add prevents duplicates, append just adds.

Ok, this would prevent the error, but it does not explain the error itself. Did
you tried it yourself? All I want to know is, if I did a mistake. If so, please
explain my error...

>> Another question:
>>
>>  Why can't I set a route on an interface that is down?
> 
> That's by some design. Use patches from linuxvirtualserver.org if
> you want them to exist.

Ok, I will try it... But what's the reason for this design?
I think, this test could be done in user-space and did not have to be in the
kernel.

> 
>> PPS: Why is ANYBODY still ignoring this e-mail for over 3 weeks?????
> 
> People are busy :-)

Ok, I understand this, but for over three weeks with so many people on this
mailing list?? :-)

Regards
 Sven

-- 
 Sven Anders <anders@anduras.de>                 () Ascii Ribbon Campaign
                                                 /\ Support plain text e-mail
 ANDURAS service solutions AG
 Innstra?e 71 - 94036 Passau - Germany
 Web: www.anduras.de - Tel: +49 (0)851-4 90 50-0 - Fax: +49 (0)851-4 90 50-55

[-- Attachment #2: anders.vcf --]
[-- Type: text/x-vcard, Size: 339 bytes --]

begin:vcard
fn:Sven Anders
n:Anders;Sven
org:ANDURAS AG;Research and Development
adr;quoted-printable:;;Innstra=C3=9Fe 71;Passau;Bavaria;94036;Germany
email;internet:anders@anduras.de
title:Dipl. Inf.
tel;work:++49 (0)851 / 490 50 - 0
tel;fax:+49 (0)851 / 4 90 50 - 55
x-mozilla-html:FALSE
url:http://www.anduras.de
version:2.1
end:vcard


[-- Attachment #3: Type: text/plain, Size: 143 bytes --]

_______________________________________________
LARTC mailing list
LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/cgi-bin/mailman/listinfo/lartc