[Bridge] Problem bridging frames with bridge and real interface MTU > 1527

Mark Zipp mark.r.zipp at gmail.com
Tue May 23 18:16:20 PDT 2006


Hi Stephen,

Thanks very much for getting back to me.

On 24/05/06, Stephen Hemminger <shemminger at osdl.org> wrote:
> On Tue, 23 May 2006 10:07:13 +0930
> "Mark Zipp" <mark.r.zipp at gmail.com> wrote:
>

<snip>
>
> The only bridge related dropping is here in br_forward.c
>
> int br_dev_queue_push_xmit(struct sk_buff *skb)
> {
>         /* drop mtu oversized packets except tso */
>         if (packet_length(skb) > skb->dev->mtu && !skb_shinfo(skb)->tso_size)
>                 kfree_skb(skb);
>
> Are you doing VLAN's?  There was a bug not fixed until 2.6.17 that didn't
> account for VLAN header properly.
>

No I'm not doing VLANs, just plain IP inside ethernet frames.

There was a new ArchLinux kernel package available, which, going by
its version number, corresponds to the 2.6.16.18 kernel. I've
installed that, and been able to send 2000 byte IP pings through the
bridge, so my problem seems to have disappeared.

> Are you doing filtering?  Some netfilter module might be dropping the packets.
>

I did have some filtering enabled originally, I've just tested my 2K
pings with and without having blanket permit lines in the incoming and
outgoing iptables rules, and have had complete success in either case.

I haven't tested it with the traffic IP/GRE traffic I originally
encountered it with yesterday, I doubt I'll now have a problem with
it, I'll let you know if I do.

(I'll create a new email to the list to start a new thread about
another thing that I think could be another bug in the bridge code -
ports go through some, if not all of the STP port states even when STP
is not running)

Thanks for your help,
Mark.




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