Re: Disabling VLAN_HWTAGGING

From: Ruslan Ermilov (ru_at_freebsd.org)
Date: 03/29/04

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    Date: Mon, 29 Mar 2004 21:38:54 +0300
To: David Gilbert <dgilbert@dclg.ca>

    On Mon, Mar 29, 2004 at 01:22:24PM -0500, David Gilbert wrote:
    > >>>>> "Jacob" == Jacob S Barrett <jbarrett@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@FreeBSD.org
FreeBSD committer

  • Next message: FreeBSD bugmaster: "Current problem reports assigned to you"

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