On 11/6/15, Raul Miller <[email protected]> wrote: > On Fri, Nov 6, 2015 at 10:26 AM, Ted Unangst <[email protected]> wrote: >> If I'm not mistaken, machines that do hardware checksumming will show an >> incorrect checksum in tcpdump. > > That sounds like it should be a problem with some specific machines, > rather than a protocol issue.
What Ted means, is the software driver for the NIC does not calculate the checksum for the packet if the hardware is capable* of taking on that task. Therefore, in those cases, tcpdump will show "bad checksum". This is expected as the HW hasn't seen the packet yet; once it does, the packet will be sent out with correct/updated checksum. --patrick * This assumes the HW is capable of checksum offloading and the driver is enabling said feature (hence, not calculating the checksum itself, in software). > Do you recall which machines exhibited this problem? > > Thanks, > > -- > Raul
