em devices not sending proper arp packets ...

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em devices not sending proper arp packets ...

Marc Fournier-4

There is a problem with the latest 4-STABLE where when you move an IP from
one server on the network to a new one, a proper arp packet isn't being
sent upstream, so the router isn't getting the change ...

It only appears to affect the new em driver, as I have other servers on
the network running an older kernel, where this doesn't happen ...

Does anyone have a 'work around' for this?

----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: [hidden email]           Yahoo!: yscrappy              ICQ: 7615664
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Re: em devices not sending proper arp packets ...

David Kirchner
On 11/14/05, Marc G. Fournier <[hidden email]> wrote:
>
> There is a problem with the latest 4-STABLE where when you move an IP from
> one server on the network to a new one, a proper arp packet isn't being
> sent upstream, so the router isn't getting the change ...
>
> It only appears to affect the new em driver, as I have other servers on
> the network running an older kernel, where this doesn't happen ...
>
> Does anyone have a 'work around' for this?

We've had this problem too. Some have suggested turning on "portfast"
on the Cisco switches, but that doesn't resolve it. It causes severely
long delays when doing net installs (sysinstall has a very long retry
time for DNS lookups, measured in minutes). Ultimately the problem is
that the driver changed some time in the 4 branch (we think it was
between 4.1 and 4.2 or 4.2 and 4.3)

What I've heard is that because the driver was submitted by Intel,
Intel should fix the bug, and the FreeBSD team will import their fix
if they make it available.

FWIW, the driver for the same NICs included with Linux 2.6 arps OK. I
might be able to run tcpdump on a Linux box and compare it to a
FreeBSD box, and suggest where the problem is, but since the last I
heard was that we're waiting on Intel to fix it, I'm not sure if it'd
do any good?
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Re: em devices not sending proper arp packets ...

Jon Simola-2
In reply to this post by Marc Fournier-4
On 11/14/05, Marc G. Fournier <[hidden email]> wrote:

> There is a problem with the latest 4-STABLE where when you move an IP from
> one server on the network to a new one, a proper arp packet isn't being
> sent upstream, so the router isn't getting the change ...

> Does anyone have a 'work around' for this?

arp -s 10.0.2.3 00:00:10:20:30:45 pub

On the "old" owner of the ip address, publish the MAC of the new owner
(10.0.2.3 being the ip that was moved, 00:00:10:20:30:45 being the new
MAC). I do this all the time as someone set this stupid Cisco switch
up with a 2 hour ARP cache and I can't change/disable it.

Once you verify that the router gets updated, delete the published arp entry.

--
Jon Simola
Systems Administrator
ABC Communications
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Re: em devices not sending proper arp packets ...

David Kirchner
In reply to this post by David Kirchner
On 11/14/05, David Kirchner <[hidden email]> wrote:
> We've had this problem too. Some have suggested turning on "portfast"
> on the Cisco switches, but that doesn't resolve it. It causes severely
> long delays when doing net installs (sysinstall has a very long retry
> time for DNS lookups, measured in minutes). Ultimately the problem is
> that the driver changed some time in the 4 branch (we think it was
> between 4.1 and 4.2 or 4.2 and 4.3)

Sorry to reply to myself here, I forgot to add: The problem is still
present in 6.0-RELEASE, and can be seen while running sysinstall.
Haven't tried 6.0-STABLE (can't get -RELEASE to install due to
unrelated bug bin/88872). According to cvsweb, 6.0-RELEASE has the
latest Intel driver.

Also: The bug you're seeing may be unrelated to the bug I was seeing,
but I suspect they may be similar. Arps just don't seem to be going
out like they should
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Re: em devices not sending proper arp packets ...

Colin Farley
I have this same problem on some production servers running
4.10-RELEASE-p16.  My work around is to set the arp cache timeout on our
2811 router to 10 seconds.

Colin



                                                                           
             David Kirchner                                                
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             Sent by:                                                   To
             owner-freebsd-sta         "Marc G. Fournier"                  
             [hidden email]           <[hidden email]>                  
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                                       [hidden email]          
             11/14/2005 02:40                                      Subject
             PM                        Re: em devices not sending proper  
                                       arp packets ...                    
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




On 11/14/05, David Kirchner <[hidden email]> wrote:
> We've had this problem too. Some have suggested turning on "portfast"
> on the Cisco switches, but that doesn't resolve it. It causes severely
> long delays when doing net installs (sysinstall has a very long retry
> time for DNS lookups, measured in minutes). Ultimately the problem is
> that the driver changed some time in the 4 branch (we think it was
> between 4.1 and 4.2 or 4.2 and 4.3)

Sorry to reply to myself here, I forgot to add: The problem is still
present in 6.0-RELEASE, and can be seen while running sysinstall.
Haven't tried 6.0-STABLE (can't get -RELEASE to install due to
unrelated bug bin/88872). According to cvsweb, 6.0-RELEASE has the
latest Intel driver.

Also: The bug you're seeing may be unrelated to the bug I was seeing,
but I suspect they may be similar. Arps just don't seem to be going
out like they should
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Re: em devices not sending proper arp packets ...

Marc Fournier-4
In reply to this post by Jon Simola-2

Sweet, thanks ... just had to use that, and works like a charm ... :)



On Mon, 14 Nov 2005, Jon Simola wrote:

> On 11/14/05, Marc G. Fournier <[hidden email]> wrote:
>
>> There is a problem with the latest 4-STABLE where when you move an IP from
>> one server on the network to a new one, a proper arp packet isn't being
>> sent upstream, so the router isn't getting the change ...
>
>> Does anyone have a 'work around' for this?
>
> arp -s 10.0.2.3 00:00:10:20:30:45 pub
>
> On the "old" owner of the ip address, publish the MAC of the new owner
> (10.0.2.3 being the ip that was moved, 00:00:10:20:30:45 being the new
> MAC). I do this all the time as someone set this stupid Cisco switch
> up with a 2 hour ARP cache and I can't change/disable it.
>
> Once you verify that the router gets updated, delete the published arp entry.
>
> --
> Jon Simola
> Systems Administrator
> ABC Communications
>
>

----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: [hidden email]           Yahoo!: yscrappy              ICQ: 7615664
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