Linux Ethernet Bridging - Apr 2007 - [Bridge] Passing vlan tagged packets through linux bridge

Hi,
I noticed the same problem with the kernel 2.6.16.21 but I
didn't try with newer kernel.

> Hi
>  
>  I have some problem with passing vlan tagged packets
> through linux bridge.
>  In the linux box eth0 , eth1  are add to br0 and the
> bridge is up and working correctly. 
>  I 've connected eth0 to trunk port of switch A and eth1
> to trunk port of switch B.
>  port 1,2,3 of each switch are in vlan 1. I've 2 client in
> the same subnet , client A connected to port 1 of switch A
> and client B connected to port 1 of switch . the problem
> is when I ping client A from clinet B or viceversa ,I
> can't ping with more than 1470bytes packet size!
>  ping will work fine by 1470byte packet size but ping with
> more than 1470bytes packet size will fail.
>  any idea??
>  
>  KasrA
>  
>  
> ---------------------------------
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>

> Fulvio Ricciardi wrote:
> > Hi,
> > I noticed the same problem with the kernel 2.6.16.21 but
> > I didn't try with newer kernel.
> >   
> 
> Use an Intel pro/100 or pro/1000 driver..they are known to
> work with VLANs.
> 
> I guess it's also possible that it's a problem in the
> bridging code, so  try the latest kernel
> as well...
I used Intel pro/100 in my test and I verified that the
interfaces work fine with vlan tagged and large packets, but
when I connect in bridge two interfaces and add a vlan to
br0 interface, this works only with small packets (< 1470
bytes).
I have not tried with latest kernel yet.

Regards
    Fulvio Ricciardi


> >   
> >> Hi
> >>  
> >>  I have some problem with passing vlan tagged packets
> >> through linux bridge.
> >>  In the linux box eth0 , eth1  are add to br0 and the
> >> bridge is up and working correctly. 
> >>  I 've connected eth0 to trunk port of switch A and
> eth1 >> to trunk port of switch B.
> >>  port 1,2,3 of each switch are in vlan 1. I've 2 client
> in >> the same subnet , client A connected to port 1 of
> switch A >> and client B connected to port 1 of switch .
> the problem >> is when I ping client A from clinet B or
> viceversa ,I >> can't ping with more than 1470bytes packet
> size! >>  ping will work fine by 1470byte packet size but
> ping with >> more than 1470bytes packet size will fail.
> >>  any idea??
> >>  
> >>  KasrA
> >>  
> >>  
> >> ---------------------------------
> >> Check out the all-new Yahoo! Mail beta - Fire up a more
> >> powerful email and get things done faster.
> >>
> >> _______________________________________________
> >> Bridge mailing list
> >> Bridge@lists.osdl.org
> >> https://lists.osdl.org/mailman/listinfo/bridge
> >>
> >>     
> > _______________________________________________
> > Bridge mailing list
> > Bridge@lists.osdl.org
> > https://lists.osdl.org/mailman/listinfo/bridge
> >   
> 
> 
> -- 
> Ben Greear <greearb@candelatech.com> 
> Candela Technologies Inc  http://www.candelatech.com
> 
> 
> _______________________________________________
> Bridge mailing list
> Bridge@lists.osdl.org
> https://lists.osdl.org/mailman/listinfo/bridge

Hi,
I noticed the same problem with the kernel 2.6.16.21 but I
didn't try with newer kernel.

Regards
    Fulvio Ricciardi
> Hi
>  
>  I have some problem with passing vlan tagged packets
> through linux bridge.
>  In the linux box eth0 , eth1  are add to br0 and the
> bridge is up and working correctly. 
>  I 've connected eth0 to trunk port of switch A and eth1
> to trunk port of switch B.
>  port 1,2,3 of each switch are in vlan 1. I've 2 client in
> the same subnet , client A connected to port 1 of switch A
> and client B connected to port 1 of switch . the problem
> is when I ping client A from clinet B or viceversa ,I
> can't ping with more than 1470bytes packet size!
>  ping will work fine by 1470byte packet size but ping with
> more than 1470bytes packet size will fail.
>  any idea??
>  
>  KasrA
>  
>  
> ---------------------------------
> Check out the all-new Yahoo! Mail beta - Fire up a more
> powerful email and get things done faster.
> 
> _______________________________________________
> Bridge mailing list
> Bridge@lists.osdl.org
> https://lists.osdl.org/mailman/listinfo/bridge
>

Hi
 
 I have some problem with passing vlan tagged packets through linux bridge.
 In the linux box eth0 , eth1  are add to br0 and the bridge is up and working
correctly.
 I 've connected eth0 to trunk port of switch A and eth1 to trunk port of
switch B.
 port 1,2,3 of each switch are in vlan 1. I've 2 client in the same subnet ,
client A connected to port 1 of switch A and client B connected to port 1 of
switch . the problem is when I ping client A from clinet B or viceversa ,I
can't ping with more than 1470bytes packet size!
 ping will work fine by 1470byte packet size but ping with more than 1470bytes
packet size will fail.
 any idea??
 
 KasrA
 
 
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Dear Roman
 
 If I don't use trunk over linux bridges(packets without vlan tag) then I
can ping more than 1500bytes(MTU).the problem is vlan tagged packets. r u sure
about jumbo frames that solve this problem ?

 
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On Fri, 01 Dec 2006 18:09:14 +0100
"Fulvio Ricciardi" <fulvio.ricciardi@zeroshell.net> wrote:
> > Use an Intel pro/100 or pro/1000 driver..they are known to
> > work with VLANs.
> > 
> > I guess it's also possible that it's a problem in the
> > bridging code, so  try the latest kernel
> > as well...
> 
> I compiled the latest 2.6.19 kernel and tested it with two
> 3COM 3c905c fast ethernet interfaces which work fine with
> vlan 802.1q tagging, but when I have added the eth0 and eth1
> to br0 the bridge doesn't forward tagged packets larger than
> 1472 bytes. I remember that with older kernels (<2.6.15)
> large tagged packets was forwarded. 
> What is the problem? Any chance to have a patch?
> Thanks in advance for your answers.
>  Best Regards
>    Fulvio Ricciardi
> 

This code might be dropping it, but don't see why because it
is already checking for VLAN

net/bridge/br_forward.c

static inline unsigned packet_length(const struct sk_buff *skb)
{
	return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
}

int br_dev_queue_push_xmit(struct sk_buff *skb)
{
	/* drop mtu oversized packets except gso */
	if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
		kfree_skb(skb);

-- 
Stephen Hemminger <shemminger@osdl.org>

> > I compiled the latest 2.6.19 kernel and tested it with
> > two 3COM 3c905c fast ethernet interfaces which work fine
> > with vlan 802.1q tagging, but when I have added the eth0
> > and eth1 to br0 the bridge doesn't forward tagged
> > packets larger than 1472 bytes. I remember that with
> > older kernels (<2.6.15) large tagged packets was
> > forwarded.  What is the problem? Any chance to have a
> > patch? Thanks in advance for your answers.
> >  Best Regards
> >    Fulvio Ricciardi
> > 
> 
> 
> This code might be dropping it, but don't see why because
> it is already checking for VLAN
> 
> net/bridge/br_forward.c
> 
> static inline unsigned packet_length(const struct sk_buff
> *skb) {
>     return skb->len - (skb->protocol == htons(ETH_P_8021Q)
> ? VLAN_HLEN : 0); }
> 
> int br_dev_queue_push_xmit(struct sk_buff *skb)
> {
>     /* drop mtu oversized packets except gso */
>     if (packet_length(skb) > skb->dev->mtu &&
> !skb_is_gso(skb))
>         kfree_skb(skb);
> 
> -- 
> Stephen Hemminger <shemminger@osdl.org>
I don't think the function  br_dev_queue_push_xmit(struct
sk_buff *skb) drops the large tagged packets because the
size limit I found with the tests is 1472 bytes and not 1496
(MTU-4).

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skype: zeroshellnet
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> Use an Intel pro/100 or pro/1000 driver..they are known to
> work with VLANs.
> 
> I guess it's also possible that it's a problem in the
> bridging code, so  try the latest kernel
> as well...
I compiled the latest 2.6.19 kernel and tested it with two
3COM 3c905c fast ethernet interfaces which work fine with
vlan 802.1q tagging, but when I have added the eth0 and eth1
to br0 the bridge doesn't forward tagged packets larger than
1472 bytes. I remember that with older kernels (<2.6.15)
large tagged packets was forwarded. 
What is the problem? Any chance to have a patch?
Thanks in advance for your answers.
 Best Regards
   Fulvio Ricciardi

--------------------------------------------------------------------
Fulvio Ricciardi
web: http://www.zeroshell.net/eng/
skype: zeroshellnet
Phone: +3908321835630