RE: [Xen-devel] Stimulating domains to send gratuitous ARPs

["Graham, Simon" <Simon.Graham@xxxxxxxxxxx>]

There are existing tools for sending arps -- the problem is knowing what IP 
address to use in the ARP -- it's actually pretty hard to know this in Dom0 
(which is where you know that the ARP needs to be sent) and if you install it 
in DomU you need a way to kick the domain to actually call the utility... (plus 
you have to install a service in DomU which is something I think is a bad idea 
to require).

Whilst I might agree that from a purist point of view having netfront do this 
is a violation of layering, it's already accepted in some other upstream 
drivers -- bonding for example; this virtual network interface driver will send 
gratuitous ARPs for the IP address associated with the bond and for any VLANs 
layered directly on top of the bond when failing over (it just wont send ARPs 
for things above the bridge if it is plugged into a bridge).

Simon

> -----Original Message-----
> From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxxxxx]
> Sent: Thursday, July 05, 2007 3:46 PM
> To: Graham, Simon
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] Stimulating domains to send gratuitous ARPs
> 
> On Thu, 2007-07-05 at 14:41 -0400, Graham, Simon wrote:
> > I accept that this is not very nice and we should probably have a
> more
> > organized/documented way to do this but Iâm not sure what would be
> > appropriate; any suggestions?
> 
> A usespace tool to send such an ARP would be a very useful thing to
> have, if it doesn't already exist.
> 
> The gratuitous arping in netfront is not very popular with the upstream
> Linux folks so this functionality is not in the paravirt_ops patches
> which are going upstream, so we'd need such a tool in the end anyway.
> 
> Ian.
> 
> 
> 
> 

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