Re: dst cache overflow and network freeze

Andi Kleen (ak@muc.de)
Mon, 20 Dec 1999 16:31:41 +0100


On Mon, Dec 20, 1999 at 01:42:11PM +0100, Kjartan Maraas wrote:
> Hi.
>
> I keep getting network freezes on 2.3.x kernels. I have a pcmcia
> 3Com 3CXE589DC card and a Dell Latitude. In the logs i get loads of
> "dst cache overflow" messages. What happens is that any existing
> connection ie. IRC. will continue to work, but I can't open a
> web page etc. fetchmail seemed to work though.
>
> from the logs:
>
> Dec 19 15:16:17 km-lt kernel: dst cache overflow
> Dec 19 15:16:22 km-lt kernel: dst cache overflow
> Dec 19 15:16:30 km-lt kernel: NET: 3 messages suppressed.
>
> Trying to telnet to a host:
>
> telnet: Unable to connect to remote host: No buffer space available
>
> The same goes for ssh.

What does arp -na say ?

The usual cause is somebody running a port scan over the local network from your
machine. If you really want to do that you can increase the values in
/proc/sys/net/ipv4/neigh/gc_thresh[123]

>
> Also in the logs I see:
>
> Dec 16 11:20:43 km-lt kernel: KERNEL: assertion (dst!=NULL)
> failed at tcp_output.c(96):tcp_advertise_mss

That is harmless.

-Andi

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