Disabling VLAN_HWTAGGING

[Ruslan Ermilov]

On Mon, Mar 29, 2004 at 01:22:24PM -0500, David Gilbert wrote:
> >>>>> "Jacob" == Jacob S Barrett <jbarrett at amduat.net> writes:
> 
> Jacob> On Thursday 25 March 2004 03:45 pm, you wrote:
> >> > Can you disable VLAN_HWTAGGING?
> >> 
> >> Not without modifying if_nge.c, but it should be pretty trivial.
> 
> Jacob> As trivial as setting chaning:
> ifp-> if_capabilities = IFCAP_HWCSUM | IFCAP_VLAN_HWTAGGING;
> Jacob> to:
> ifp-> if_capabilities = 0;
> 
> Jacob> This didn't solve the problem completely though.  On the remote
> Jacob> host I can now see tagged frames from the if_nge host, but the
> Jacob> reply frames from the if_em host or not visible at all on the
> Jacob> if_nge host (via tcpdump).
> 
> Are you dumping all packets?  We've found that you can dump a specific
> vlan on nge's, but you can't get good data by dumping the raw port
> itself.  No matter how it's set, in both Linux and FreeBSD, many nge
> chipsets will not show vlan packets from the driver with a tcpdump.
> 
Hmm, you can't probably see it because the hardware is configured to
do VLAN tag insertion/removal, and stores VLAN data decoupled from the
frame's mbuf chain.  And BPF is very unlikely to reconstruct the
ETHERTYPE_VLAN packet using this information...


Cheers,
-- 
Ruslan Ermilov
ru at FreeBSD.org
FreeBSD committer
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