Re: What does "Neighbour table overflow" message indicate?

jeff millar (jeff@wa1hco.mv.com)
Sun, 29 Jul 2001 09:50:59 -0400


We used to get this from an embedded PowerPC processor under 2.2.x when the
hardware to device driver interface got screwed up.

jeff

----- Original Message -----
From: "Riley Williams" <rhw@MemAlpha.CX>
To: "Steve Snyder" <swsnyder@home.com>
Cc: "Linux Kernel" <linux-kernel@vger.kernel.org>
Sent: Sunday, July 29, 2001 1:41 AM
Subject: Re: What does "Neighbour table overflow" message indicate?

> Hi Steve.
>
> > I just got this sequence of messages in my system log:
> >
> > Jul 28 19:47:44 sunburn kernel: Neighbour table overflow.
> > Jul 28 19:47:44 sunburn last message repeated 9 times
> > Jul 28 19:47:49 sunburn kernel: NET: 53 messages suppressed.
> > Jul 28 19:47:49 sunburn kernel: Neighbour table overflow.
> > Jul 28 19:48:07 sunburn kernel: NET: 21 messages suppressed.
> > Jul 28 19:48:07 sunburn kernel: Neighbour table overflow.
> > Jul 28 19:48:09 sunburn last message repeated 3 times
> > Jul 28 19:48:14 sunburn kernel: NET: 4 messages suppressed.
> > Jul 28 19:48:14 sunburn kernel: Neighbour table overflow.
> >
> > This is on a RedHat v7.1 + SMP kernel v2.4.7 system. What is
> > the kernel trying to tell me here?
> >
> > Please cc me as I am not a subscriber to this list.
>
> This could be on completely the wrong track, but here's one of the
> entries from the 2.4.5 kernel's Configure.help file (I don't yet have
> 2.4.7 on my system):
>
> Q> ARP daemon support (EXPERIMENTAL)
> Q> CONFIG_ARPD
> Q> Normally, the kernel maintains an internal cache which maps IP
> Q> addresses to hardware addresses on the local network, so that
> Q> Ethernet/Token Ring/ etc. frames are sent to the proper address
> Q> on the physical networking layer. For small networks having a
> Q> few hundred directly connected hosts or less, keeping this
> Q> address resolution (ARP) cache inside the kernel works well.
> Q>
> Q> However, maintaining an internal ARP cache does not work well
> Q> for very large switched networks, and will use a lot of kernel
> Q> memory if TCP/IP connections are made to many machines on the
> Q> network.
> Q>
> Q> If you say Y here, the kernel's internal ARP cache will never
> Q> grow to more than 256 entries (the oldest entries are expired
> Q> in a LIFO manner) and communication will be attempted with the
> Q> user space ARP daemon arpd. Arpd then answers the address
> Q> resolution request either from its own cache or by asking the
> Q> net.
> Q>
> Q> This code is experimental and also obsolete. If you want to
> Q> use it, you need to find a version of the daemon arpd on the
> Q> net somewhere, and you should also say Y to "Kernel/User
> Q> network link driver", below. If unsure, say N.
>
> The text in there looks suspiciously related to your problem to me.
>
> Best wishes from Riley.
>
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