Subject: Re: [vserver] ping vs. IP address vs. MAC (address)
From: Dennis Roos <dennis.roos@gmail.com>
Date: Fri, 01 May 2009 23:02:21 +0200

What you could do is clear the arp entry for the address on your 
router/switch and generate some traffic (eg. ping) on the interface.
Mostly it takes 5 minutes for a router to learn about the new address, 
as it caches the information for that amount of time.

Best regards,
Dennis Roos


Roderick A. Anderson wrote:
> I'm asking for a clue stick here.  First time I've run into this issue 
> ... hard.  Be a few times where it took a bit for outbound traffic to 
> get a route but can't remember running into this problem.
>
> The short question is: does the network/NIC _know_ which IP address it 
> is responding for when a ping request comes in or does it just respond 
> to the ping request at the MAC (hardware?) level?
>
> I have two hosts and each of their guests has its own IP address. I am 
> trying to move the guest's services from one host to the other.  The 
> new and old guests both use the same IP address.  So I shut down the 
> old guest and then start up the new guest on the other system.  
> Network traffic to the new guest, except pings, doesn't work.  
> Iptables, ip addr ls, ifconfig, etc., all appear to be good.
>
> I'm guessing the routing is sending the ping request to the old 
> guest's MAC.
>
> Thoughts, Ideas?
>
> \\||/
> Rod