Re: disable tag stripping on Intel

Zoilo Gomez wrote:
> Hi Joe, and others on this group,
> 
> I found your messages from March 2005 in this VLAN candelatech.com
> mailing list, concerning VLAN stripping on Intel. Have you ever been
> able to get this working?
> 
> I have the following setup on a router (gentoo / linux-2.6.16.20):
> => eth0: external DSL link
> => eth1: internal e1000 gigabit nic, connected to hp2626 vlan-switch.
> 
> On eth1, I have created several VLANs, say vlan1 - vlan9, to separate
> different groups of clients / traffic.
> 
> As pointed out by you and others, the hardware vlan insertion/stripping
> makes that, if a ping is performed through eg. vlan2, then:
> => tcpdump -n -i vlan2: will reveal both icmp-request en icmp-reply
> packets (untagged), however
> => tcpdump -n -i eth1: will reveal only the icmp-request packets, and in
> untagged format.
> 
> WYSINWYG!
> 
> What I need to do is traffic-shaping (http://www.lartc.org) based on
> VLAN. I want to use iptables/ebtables to mark packets on different
> vlans, so I can use 'tc filter' on eth1 to sort them into different
> classes for my qdisc. DSL (eth0) download shaping must occur on eth1
> (egress interface). It cannot be done on individual vlan interfaces,
> since then there would be no way to have them use each others unused
> bandwidth.
> 
> But if I understand things correctly, then this is in fact impossible,
> because I cannot seem to match/mark these packets in any way on eth1 (in
> spite of the spooky egress vlan traffic on eth1 / tcpdump !?! You can
> see it, but you cannot match it).
> 
> So besides it being a nuisance that tcpdump is in fact broken (showing
> things that are not there, and not showing things that are there) it
> seems impossible to do proper traffic shaping, because of the hardware
> vlan tagging. When I try this on a e100 (no hardware vlan tagging) then
> tcpdump works as expected (I see all tagged packets on eth1, and I see
> all untagged packets on vlanX) and I can also match the packets as
> expected.
> 
> AFAICS there is no easy way to disable hardware tagging on e1000, so I
> would need to hack the driver.
> 
> Is there another way to work around this?
> 
> Or perhaps does someone know another Gigabit NIC where hardware vlan
> tagging can easily be disabled (or is absent)?
> 
> Any suggestions / experiences will be greatly appreciated !

You not see the packets with tcpdump on eth1, but they are there.
Just attach tc filters on eth1 and use marking.
I have also this situation and works perfectly.

> Z.
> 
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