ip change detection

it's possible to detect an ip change at application level?
If I move the network cable from a network to another one, the dhcp client
do not renew automatically the ip number (in Windows it happens). There's a
way to configure the dhcp client to concern about network changes, in that
way, in a wireless scenario, we could change ip automatically, and if
there's a way to notify this change to applications that uses UDP packets
(see Voip) the application can make the right moves....

thanks in advance,
Alx

Runamok wrote:

> it's possible to detect an ip change at application level?
> If I move the network cable from a network to another one, the dhcp client
> do not renew automatically the ip number (in Windows it happens).->Windows
does a lot of things, but, as it appears to me, this is not an performance
increase we experience, using a windows machine.
Well, as a workaround, you could do pings on the subnet your working in. As
soon as you cannot reach an other machine, tell the dhcpd to renew its
address.
> There's
> a way to configure the dhcp client to concern about network changes, in
> that way, in a wireless scenario, we could change ip automatically, and if
> there's a way to notify this change to applications that uses UDP packets
> (see Voip) the application can make the right moves....
>
> thanks in advance,
> Alx
Alex

"Alex Harsch" <(E-Mail Removed)> ha scritto nel messaggio
news:c77cmd$2uhu$(E-Mail Removed)...
> Runamok wrote:
>
> > it's possible to detect an ip change at application level?
> > If I move the network cable from a network to another one, the dhcp
client
> > do not renew automatically the ip number (in Windows it happens).
>Windows
> does a lot of things, but, as it appears to me, this is not an performance
> increase we experience, using a windows machine.
> Well, as a workaround, you could do pings on the subnet your working in.
As
> soon as you cannot reach an other machine, tell the dhcpd to renew its
> address.

We can also listen at router advertisements but, again, how can I detect
that ICMP packet at application level?

Alx

"Runamok" <(E-Mail Removed)> wrote in message news:<c76bbp$ba7$(E-Mail Removed)>...
> it's possible to detect an ip change at application level?
> If I move the network cable from a network to another one, the dhcp client
> do not renew automatically the ip number (in Windows it happens). There's a
> way to configure the dhcp client to concern about network changes, in that
> way, in a wireless scenario, we could change ip automatically, and if
> there's a way to notify this change to applications that uses UDP packets
> (see Voip) the application can make the right moves....
>
> thanks in advance,
> Alx

Not sure what happens with your app, but re: dhcp renewals ...

The dhcp client only acquires a lease when the interface is brought
up. Changing the patch cord out is not enough -- you would have to
reboot the machine or ifconfig down followed by ifconfig up.

But wait ... that may (very likely) will cause the dhcp client to
attempt to renew the _old_ setup. This is getting to be a pain ...

To automatically get link state changes to trigger a new/"proper" dhcp
request (like Windows) you can try this:
http://www.stud.uni-hamburg.de/users...jects/ifplugd/
Check your distro, as some (like Mandrake) include it by default --
sounds like yours does not (like Redhat).

I think this is what you're looking for.

hth,
prg
email above disabled