Adding Virtual IP Address

Hi,

I have a problem in shutting down an already added virtual ip thru
ifconfig. Consider this snippet below :

/sbin/ifconfig eth0:1 192.168.220.1 netmask 255.255.255.255 up
/sbin/ifconfig eth0:2 192.168.220.2 netmask 255.255.255.255 up
/sbin/ifconfig eth0:3 192.168.220.3 netmask 255.255.255.255 up

I am adding three virtual ip address on eth0 interface. Now if I try
to down, for example, 192.168.220.2 , i don't have problems. But If I
try to down the IP, 192.168.220.1, I see that all the other virtual
ips 192.168.220.2 and 192.168.220.3 are also gone. I am not able to
ping any of the other ips also.

Now, just change the order of the snippet below :
/sbin/ifconfig eth0:2 192.168.220.2 netmask 255.255.255.255 up
/sbin/ifconfig eth0:1 192.168.220.1 netmask 255.255.255.255 up
/sbin/ifconfig eth0:3 192.168.220.3 netmask 255.255.255.255 up

Now If down the virtual ip 192.169.220.2, the other vips are also
gone.

Put simply, whenever i down the first virtual ip , all the other vips
also goes down.

Why is it so ? Am i missing something ?

Thanks,
Vijay.


Vijay

On 24 May 2004 07:05:53 -0700, Vijay <(E-Mail Removed)> wrote:
> Hi,
>
> I have a problem in shutting down an already added virtual ip thru
> ifconfig. Consider this snippet below :
>
> /sbin/ifconfig eth0:1 192.168.220.1 netmask 255.255.255.255 up
> /sbin/ifconfig eth0:2 192.168.220.2 netmask 255.255.255.255 up
> /sbin/ifconfig eth0:3 192.168.220.3 netmask 255.255.255.255 up
>
> I am adding three virtual ip address on eth0 interface. Now if I try
> to down, for example, 192.168.220.2 , i don't have problems. But If I
> try to down the IP, 192.168.220.1, I see that all the other virtual
> ips 192.168.220.2 and 192.168.220.3 are also gone. I am not able to
> ping any of the other ips also.

What happens if you down the alias _interface_ instead of the IP, ie,
'ifconfig eth0:1 down'? BTW the first alias is eth0:0, but it does not
matter if you skip it or start at any other number.

--
David Efflandt - All spam ignored http://www.de-srv.com/

Vijay <(E-Mail Removed)> wrote:

> /sbin/ifconfig eth0:1 192.168.220.1 netmask 255.255.255.255 up
> /sbin/ifconfig eth0:2 192.168.220.2 netmask 255.255.255.255 up
> /sbin/ifconfig eth0:3 192.168.220.3 netmask 255.255.255.255 up

So what's assigned to eth0? (no alias)

--
Cameron Kerr
(E-Mail Removed) : http://nzgeeks.org/cameron/
Empowered by Perl!

Cameron Kerr <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> Vijay <(E-Mail Removed)> wrote:
>
> > /sbin/ifconfig eth0:1 192.168.220.1 netmask 255.255.255.255 up
> > /sbin/ifconfig eth0:2 192.168.220.2 netmask 255.255.255.255 up
> > /sbin/ifconfig eth0:3 192.168.220.3 netmask 255.255.255.255 up
>
> So what's assigned to eth0? (no alias)

eth0 has my machine IP (original ipaddress). I also tried shutting
down the interface using the following command as u mentioned, but in
vain.

'ifconfig eth0:1 down'

Thanks,
Vijay.

Cameron Kerr <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> Vijay <(E-Mail Removed)> wrote:
>
> > /sbin/ifconfig eth0:1 192.168.220.1 netmask 255.255.255.255 up
> > /sbin/ifconfig eth0:2 192.168.220.2 netmask 255.255.255.255 up
> > /sbin/ifconfig eth0:3 192.168.220.3 netmask 255.255.255.255 up
>
> So what's assigned to eth0? (no alias)

Phew !!! I have configured the vips using the netmask as 255.255.255.0
and not 255.255.255.255 as mentioned in this mail. u ppl might have
helped, but for the typo. I m sorry. It works now.

Thanks for all ur efforts.

Vijay.

(E-Mail Removed) (Vijay) wrote in message news:<(E-Mail Removed) om>...
> Cameron Kerr <(E-Mail Removed)> wrote in message news:<(E-Mail Removed)>...
> > Vijay <(E-Mail Removed)> wrote:
> >
> > > /sbin/ifconfig eth0:1 192.168.220.1 netmask 255.255.255.255 up
> > > /sbin/ifconfig eth0:2 192.168.220.2 netmask 255.255.255.255 up
> > > /sbin/ifconfig eth0:3 192.168.220.3 netmask 255.255.255.255 up

Of course, you know that there is no "real" /32 network -- wonder if
that is also part of the gotcha? See below ...

> > So what's assigned to eth0? (no alias)
>
> eth0 has my machine IP (original ipaddress). I also tried shutting
> down the interface using the following command as u mentioned, but in
> vain.
>
> 'ifconfig eth0:1 down'
>
> Thanks,
> Vijay.

You may be running into a shortcoming of ifconfig -- all things ip in
Linux run through the ip command. ifconfig uses ip for relatively
simple tasks but has not been re-written to interface with ip to
handle "aliases" very well.

With the extensive re-working of the IP stack in 2.2.?? links
(interfaces) and ip addresses are treated independently -- adds
greater flexibility to the configuration and routing code, etc.

Currently, with your approach, it _seems_ the first ip address you
assign is a "primary" address, the following are "secondary"
addresses. ip behavior is that if you delete the primary, the
secondaries will also be deleted. The details are not well documented
and I don't understand all the ramifications myself -- another gotcha
is that interfaces are referenced by index # in the code and
_sometimes_ the order of configuration matters (like here?). Not sure
just how ifconfig uses ip, but your netmask of /32 would be the
"right" approach with ip -- all primaries -- but the alias naming
causes a hiccup ...?

You should have a copy of ip-cref on your machine, or try here for an
html version:
http://linux-ip.net/gl/ip-cref/
There is a script -- ifcfg -- at the end that may help or shed light
....

This thread is not a full discussion, but may get you started ...
http://www.uwsg.iu.edu/hypermail/lin...10.3/0003.html
note: I was too busy to chase down the start

Have you tried adding/deleting the addresses with ip instead of
ifconfig? The "best" way may also depend on how/why you're using the
addresses.

Working through qdiscs can seem simple compared to some of the quirks
of ip/ifconfig ;-(

hth,
rpg
email above disabled