Re: Rusty's brain broke!

From: Sumit Pandya (sumit@elitecore.com)
Date: Thu Jul 24 2003 - 09:36:33 EST


Hi,
    Again I'd say search google for "Neighbour table overflow".
    Short answer is

    If you get message "Neighbour table overflow." in dmesg then you need to
increase ARP related parameters as following. It is good to set in rc.local
or via sysctl . All are in /proc/sys/net/ipv4/neigh/default/ directory.
"Desired" indicate to set value when you encounter problem. This is normally
suggest double of your existing value and it is in power of 2.

gc_thresh1
The minimum number of entries to keep in the ARP cache. The garbage
collector will not run if there are fewer than this number of entries in the
cache. Defaults to 128.
Desired: 256

gc_thresh2
The soft maximum number of entries to keep in the ARP cache. The garbage
collector will allow the number of entries to exceed this for 5 seconds
before collection will be performed. Defaults to 512.
Desired: 1024

gc_thresh3
The hard maximum number of entries to keep in the ARP cache. The garbage
collector will always run if there are more than this number of entries in
the cache. Defaults to 1024.
Desired: 2048

gc_stale_time
Determines how often to check for stale neighbour entries. When a neighbour
entry is considered stale it is resolved again before sending data to it.
Defaults to 60 seconds.
Desired: 120
    Hope no complains again.
-- Sumit

----- Original Message -----
From: "Bartosz Feński aka fEnIo" <fenio@o2.pl>
Sent: Thursday, July 24, 2003 7:09 PM

On Wed, Jul 23, 2003 at 08:48:19PM +0200, Bartosz Fe=F1ski aka fEnIo wrote:
> Whell... it happened.
>=20
> Jul 23 07:51:42 localhost kernel: MASQUERADE: No route: Rusty's brain bro=
ke!
> Jul 23 07:51:43 localhost kernel: MASQUERADE: No route: Rusty's brain bro=
ke!
> Jul 23 07:51:44 localhost kernel: MASQUERADE: No route: Rusty's brain bro=
ke!
>=20
> (root@rtr)/var/log$grep Rusty syslog | wc -l
> 136451
> (root@rtr)/var/log$
>=20
> And it seems that it's quite often.
>=20
> Can you tell me what else should I tell you to help debug that problem?
Ok... I've got one anwer, and someone asked me to read netiquette and
search the Google. I searched before I wrote here.

(root@rtr)~$cat /proc/sys/net/ipv4/ip_conntrack_max=20
131072
(root@rtr)~$

(root@rtr)~$cat /proc/net/ip_conntrack | wc -l
  23331
(root@rtr)~$

And I still have in my logs:

Jul 24 15:32:37 localhost kernel: NET: 169 messages suppressed.
Jul 24 15:32:37 localhost kernel: Neighbour table overflow.
Jul 24 15:32:37 localhost kernel: MASQUERADE: No route: Rusty's brain broke!

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