netdev - Re: vlan tagging problem

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Date:   Wed, 12 Apr 2017 11:45:16 +0200
From:   Michal Kubecek <mkubecek@...e.cz>
To:     netdev@...r.kernel.org
Cc:     carl h <heyen2000@...il.com>
Subject: Re: vlan tagging problem

On Tue, Apr 11, 2017 at 03:36:50PM -0400, carl h wrote:
> 
> I tried to manually configure a vlan on my target device. I use these
> 2 vlan config commands, then I ping an IP address and sniff the
> packets to look for the vlan tag in the messages.
> 
>    vconfig add esw0
>    ifconfig esw0.10 10.93.1.2 netmask 255.255.255.0

I would rather suggest

  ip link add esw0.10 link esw0 type vlan id 10
  ip addr add 10.93.1.2/24 brd + dev esw0.10
  ip link set esw0.10 up

> Despite my attempts, tagging does not occur in any outgoing packets.

How do you check? If with tcpdump, on which interface?

> However when I tried the exact same method and commands on my Ubuntu
> workstation vlan tagging did work without problems.
> 
>     Target: mips32, Linux 2.6.39, 802.1Q driver version 1.8

With older versions of libpcap, tcpdump wouldn't show VLAN tags if vlan
information was passed in metadata rather than as a tag in packet itself
(which is usually the case when outgoing/incoming device supports
hardware vlan tagging/stripping). Make sure this is not your case.

Michal Kubecek