From: Ian Pilcher <arequipeno@gmail•com>
To: netdev@vger•kernel.org
Subject: Re: Proxy ARP causing Neighbour table overflow
Date: Sun, 13 Jan 2013 10:08:42 -0600 [thread overview]
Message-ID: <kcum67$md5$1@ger.gmane.org> (raw)
In-Reply-To: <kchkrs$nmb$1@ger.gmane.org>
Is there a better list on which to ask this question?
On 01/08/2013 11:26 AM, Ian Pilcher wrote:
> I am using proxy ARP to divide my home network into several different
> subnets, while allowing them all to communicate through my residential
> "router". I am seeing a (very) large number of "Neighbour table over-
> flow" messages, although I haven't noticed any impact on connectivity or
> performance.
>
> (If you're not familiar with proxy ARP, it's pretty cool. See
> http://en.wikipedia.org/wiki/Proxy_ARP.)
>
> Some details on my setup:
>
> * I have configured my residential router (Verizon FiOS) to use all of
> 172.31.0.0/16 as my home network.
>
> * The routers internal IP address is 172.31.255.254. As expected its
> subnet mask is 255.255.0.0.
>
> * I have configured the router's built-in DHCP server to provide
> addresses within the range 172.31.255.151 - 172.31.255.253 (along with
> a subnet mask of 255.255.0.0). Normally, the only devices using these
> addresses are my FiOS set-top boxes.
>
> * My subnets run on separate VLANs. Routing between them is provided by
> a small server running CentOS 6.3 (32-bit). The server has a dual-
> port NIC, and it is using mode 6 (balance-alb) bonding. Thus, the
> interfaces on the server range from bond0.249 - bond0.255.
>
> * The "upstream" IP address of my server (on bond0.255) is
> 172.31.255.1; it's subnet mask is 255.255.255.0. (Note the
> difference from the router's subnet mask.)
>
> * The server acts as the default gateway for the other subnets --
> 172.31.249.0/24 (on bond0.249, 172.31.249.254) through 172.31.254.0/24
> (on bond0.254, 172.31.249.254).
>
> * I have set "net.ipv4.conf.bond0/255.proxy_arp = 1" in
> /etc/sysctl.conf. When the server sees an ARP request on bond0.255
> for an address in the range 172.31.249.1 - 172.31.254.254, it responds
> with its own MAC (actually, one of its two MACs because of the way
> mode 6 bonding works).
>
> Despite all this complexity (for a home network at least), I really
> don't have a huge number of devices. Running "arp -n | wc -l" on the
> server shows that it has 15 entries in its ARP cache right now, which is
> about normal. It may go up a bit when I spin up a bunch of VMs, but not
> by that much.
>
> So why am I getting the "Neighbour table overflow" messages. Everything
> I can Google up on this messages indicates that it happens with "large,
> flat networks" with a lot of users. I do sort of have a large flat
> network, but that's really only true from the router's point of view.
>
> (I should note that I only recently configured Ethernet bonding, I was
> seeing the "Neighbour table overflow" messages when I was using only a
> single interface.)
>
> Any ideas?
>
> Thanks!
>
--
========================================================================
Ian Pilcher arequipeno@gmail•com
Sometimes there's nothing left to do but crash and burn...or die trying.
========================================================================
prev parent reply other threads:[~2013-01-13 16:08 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-08 17:26 Proxy ARP causing Neighbour table overflow Ian Pilcher
2013-01-13 16:08 ` Ian Pilcher [this message]
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