gratuitous ARP with em interface.

[Sreekanth]

A related topic.Whenever an alias gets added to the interface, the
interface is reset.In my opinion this is uncalled for.The Interface
should be reset only when adding the first Ip address.As far as
interface is concerned Adding an IP address has no effect,except in the
first instance.My suggestion is to use the flags IFF_RUNNING|IFF_OACTIVE
to decide if we want to reset the interface again.

Comments..?

Sreekanth


> -----Original Message-----
> From: owner-freebsd-net at freebsd.org 
> [mailto:owner-freebsd-net at freebsd.org] On Behalf Of Sreekanth
> Sent: Thursday, May 29, 2003 9:36 AM
> To: mvsjetti at hss.hns.com
> Cc: freebsdnic at mailbox.cps.intel.com; 
> freebsd-net at freebsd.org; akanwar at digitarchy.com
> Subject: RE: gratuitous ARP with em interface.
> 
> 
> em_ioctl() has a call to ether_ioctl() which in turn calls 
> arp_ifinit().
> 
> Sreekanth
> 
> > -----Original Message-----
> > From: mvsjetti at hss.hns.com [mailto:mvsjetti at hss.hns.com]
> > Sent: Thursday, May 29, 2003 9:17 AM
> > To: Sreekanth
> > Cc: 'Petri Helenius'; 'Ruslan Ermilov'; 
> > freebsdnic at mailbox.cps.intel.com; freebsd-net at freebsd.org; 
> > akanwar at digitarchy.com
> > Subject: RE: gratuitous ARP with em interface.
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > hi,
> > I had checked the kernel code of the freeBsd. In case of fxp
> > port " fxp_ether_ioctl" fucntional will be called when we add 
> > a new address to an interface(using the if_ioctl pointer from 
> > the in_ifinit fucntion). And this fuction will inturn call 
> > the arp_ifinit fucntion which sends the gratituos ARP. I am 
> > not able to find this kind of fucntionality for em. I am not 
> > the sure whether the code i am having was incomplete or some 
> > fucntonality was missing in the implementation. This may be 
> > the case of incomplete intitlaization( if_ioctl of the ifp 
> > may not be initlized properly).
> > 
> > If u can do kernel debugging put break point at the
> > "arp_ifinit" and verify if this was getting called or 
> > not.................. cheers, mahesh
> > 
> > 
> > 
> > 
> > "Sreekanth" <sreekanth at redlinenetworks.com>@freebsd.org on
> > 29/05/2003 21:01:29
> > 
> > Sent by:    owner-freebsd-net at freebsd.org
> > 
> > 
> > To:    "'Petri Helenius'" <pete at he.iki.fi>, "'Ruslan Ermilov'"
> >        <ru at freebsd.org>
> > cc:    freebsdnic at mailbox.cps.intel.com, freebsd-net at freebsd.org,
> >        akanwar at digitarchy.com
> > 
> > Subject:    RE: gratuitous ARP with em interface.
> > 
> > 
> > Could be attributed to the spanning tree in the switch.I have
> > seen it happening(especially with cisco switches).I bet you 
> > are not able to send out any packet(Not just Garp).
> > 
> > Sreekanth
> > 
> > > -----Original Message-----
> > > From: owner-freebsd-net at freebsd.org
> > > [mailto:owner-freebsd-net at freebsd.org] On Behalf Of Petri Helenius
> > > Sent: Thursday, May 29, 2003 4:39 AM
> > > To: Ruslan Ermilov
> > > Cc: freebsdnic at mailbox.cps.intel.com; akanwar at digitarchy.com; 
> > > freebsd-net at freebsd.org
> > > Subject: Re: gratuitous ARP with em interface.
> > >
> > >
> > >
> > > I haven't looked that deep into why, but em is quite slow
> > on coming up
> > > compared to
> > > fxp for example. Probably something to do with hardware 
> > > re-initialization.
> > >
> > > Pete
> > >
> > >
> > > Ruslan Ermilov wrote:
> > >
> > > >On Wed, May 28, 2003 at 07:57:07PM -0400,
> > > akanwar at digitarchy.com wrote:
> > > >
> > > >
> > > >>Hi all,
> > > >>
> > > >>Is there a known issue with alias IPs on em interfaces not
> > > sending out
> > > >>gratuitous arps ?
> > > >>
> > > >>The situation is as follows:
> > > >> I am running a custom redundancy daemon that migrates the
> > > IP address
> > > >>of a server from one interface to another in case the
> > > active network
> > > >>path fails. Till now I was experimenting with two fxp
> > > interfaces and
> > > >>everything worked perfectly. i.e. when the ip address moved over
> > > >>(using a perl script to run ifconfig commands) it sent out
> > > grat. arps
> > > >>for each of its alias IPs. This allowed the router to
> > > update its Arp
> > > >>table and talk to the newly active interface.
> > > >>
> > > >>Now when I try running the code with em (gigabit Ethernet
> > > over copper)
> > > >>NICs, I simply do not see the gratuitous arps come out 
> of the new
> > > >>interface.
> > > >>
> > > >>I am at a loss to understand what has changed. Could it
> > be that the
> > > >>line DOWN -> UP time of the em interface is longer thereby
> > > causing a
> > > >>loss of ARPs ? Any suggestions ?
> > > >>
> > > >>
> > > >>
> > > >Yes, I can reproduce this too, no gratuitous ARP is sent.
> > > >
> > > >
> > > >Cheers,
> > > >
> > > >
> > >
> > >
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