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[lvs-users] Cisco routers dynamic ARP caching

 

 

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antonioams at gmail

Sep 12, 2007, 3:06 PM

Post #1 of 2 (381 views)
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[lvs-users] Cisco routers dynamic ARP caching

Dear All,

We faced with the same problem described by the original post from *Greg
Woods* woods at ucar.edu
<lvs-users%40linuxvirtualserver.org?Subject=Re:%20Cisco%20routers%20dynamic%20ARP%20caching&In-Reply-To=%3C200208021715.g72HFQD11154%40mailman.ucar.edu%3E>,
and the short answer is yes, the Cisco Router makes dynamic arp caching, in
our case the Cisco Router are using the arp request sent by the Directors
machine to update the mac address of the vip in the router arp table, this
were happening because the arp request was being sent with VIP as the source
address of the arp request packet.

To solve this issue we change the net.ipv4.conf.all.arp_announce and
net.ipv4.conf.bond0.arp_announce (bond0 is the interface in use) parameter
to value 2 in the /etc/sysctl.conf configuration file [1], this
configuration change the behaviour of all arp request sent by the machine,
the source ip address in the arp request is sent as the RIP instead of VIP,
in our case this prevent the Cisco Router to update VIP arp table entry.

I knew that this post is really old, and probably *Greg Woods* woods at
ucar.edu<lvs-users%40linuxvirtualserver.org?Subject=Re:%20Cisco%20routers%20dynamic%20ARP%20caching&In-Reply-To=%3C200208021715.g72HFQD11154%40mailman.ucar.edu%3E>already
solved his problem, i am only sending this post to share our
experience with others LVS users.

References
[1] -
http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.arp_problem.html#2_6_arp_announce

Best regards,

--
Antonio Anderson M. Souza
Project Manager
Voice Technology
Rua: Libero BadarĂ³, 293
Cj 30D - 30o. andar
CEP: 01009-907
antonio [at] voicetechnology
phone: +55 11 3588-0188
mobile: +55 11 8224-2756

--
Antonio Anderson M. Souza
Project Manager
Voice Technology
Rua: Libero BadarĂ³, 293
Cj 30D - 30o. andar
CEP: 01009-907
antonio [at] voicetechnology
phone: +55 11 3588-0188
mobile: +55 11 8224-2756
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jmack at wm7d

Sep 12, 2007, 4:46 PM

Post #2 of 2 (341 views)
Permalink
Re: [lvs-users] Cisco routers dynamic ARP caching [In reply to]

On Wed, 12 Sep 2007, Antonio Anderson M. de Souza wrote:

> Dear All,

> We faced with the same problem described by the original
post from *Greg
Woods* woods at ucar.edu
<lvs-users%40linuxvirtualserver.org?Subject=Re:%20Cisco%20routers%20dynamic%20ARP%20caching&In-Reply-To=%3C200208021715.g72HFQD11154%40mailman.ucar.edu%3E>,
and the short answer is yes, the Cisco Router makes dynamic arp caching, in
our case the Cisco Router are using the arp request sent by the Directors
machine to update the mac address of the vip in the router arp table, this
were happening because the arp request was being sent with VIP as the source
address of the arp request packet.

> To solve this issue we change the
net.ipv4.conf.all.arp_announce and
net.ipv4.conf.bond0.arp_announce (bond0 is the interface in use) parameter
to value 2 in the /etc/sysctl.conf configuration file [1], this
configuration change the behaviour of all arp request sent by the machine,
the source ip address in the arp request is sent as the RIP instead of VIP,
in our case this prevent the Cisco Router to update VIP arp table entry.

Hi Antonio
Thanks for the update.

I don't understand the result of your cure. When the
router asks "who has VIP, tell router" what do the
realservers reply?


> I knew that this post is really old, and probably *Greg
Woods* woods at
ucar.edu<lvs-users%40linuxvirtualserver.org?Subject=Re:%20Cisco%20routers%20dynamic%20ARP%20caching&In-Reply-To=%3C200208021715.g72HFQD11154%40mailman.ucar.edu%3E>already
solved his problem, i am only sending this post to share our
experience with others LVS users.

Never too late to fill gaps in our knowledge

Thanks Joe

--
Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at http://www.wm7d.net/azproj.shtml
Homepage http://www.austintek.com/ It's GNU/Linux!

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