TCP checksum - HP UX

This is a discussion on TCP checksum - HP UX ; HP-UX B.11.23 ia64 How can we know if the TCP checksum is done by HW (the used NIC) or by software? Alex Vinokur email: alex DOT vinokur AT gmail DOT com http://mathforum.org/library/view/10978.html http://sourceforge.net/users/alexvn...

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Thread: TCP checksum

  1. TCP checksum

    HP-UX B.11.23 ia64


    How can we know if the TCP checksum is done by HW (the used NIC) or by
    software?


    Alex Vinokur
    email: alex DOT vinokur AT gmail DOT com
    http://mathforum.org/library/view/10978.html
    http://sourceforge.net/users/alexvn

  2. Re: TCP checksum

    Alex Vinokur wrote:
    > HP-UX B.11.23 ia64


    > How can we know if the TCP checksum is done by HW (the used NIC) or
    > by software?


    That would I suspect be via some lanadmin command.

    More broadly, a while back, HP-UX stopped enabling CKO (ChecKsum
    Offload) on 1G links by default. It will enable it on 10G links by
    default. The last time I checked IB, none of the IB links out there
    even offered CKO, but that may have changed, although I don't know if
    that would have been reflected in the offerings for the Integrity
    servers running HP-UX.

    Also, if you were to use caliper to
    profile the system you could see or not see the checksum routines
    being called and consuming non-epsilon quantities of CPU time.

    rick jones
    --
    denial, anger, bargaining, depression, acceptance, rebirth...
    where do you want to be today?
    these opinions are mine, all mine; HP might not want them anyway...
    feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

  3. Re: TCP checksum

    On May 12, 2:55 pm, Alex Vinokur wrote:
    > HP-UX B.11.23 ia64
    >
    > How can we know if the TCP checksum is done by HW (the used NIC) or by
    > software?
    >

    Check the value of `flags' in the output of `ifconfig' on the
    interface you're interested in. If you see `CKO', the hardware
    is doing TCP/IP checksum calculation; if not, the software
    stack is.


    Mathen

  4. Re: TCP checksum

    Rick Jones writes:

    > Alex Vinokur wrote:
    >> HP-UX B.11.23 ia64

    >
    >> How can we know if the TCP checksum is done by HW (the used NIC) or
    >> by software?

    >
    > That would I suspect be via some lanadmin command.


    Assuming "latest technology" form HP, the suggested command should be "nwmgr
    -g --st -c btlan" (or so).

    As an interesting note: While HP docs say that lanadmin and comparables are
    considered obsolete, their current VLAN configuration script still uses
    lanadmin instead of nwmgr. ;-)

    >
    > More broadly, a while back, HP-UX stopped enabling CKO (ChecKsum
    > Offload) on 1G links by default. It will enable it on 10G links by
    > default. The last time I checked IB, none of the IB links out there
    > even offered CKO, but that may have changed, although I don't know if
    > that would have been reflected in the offerings for the Integrity
    > servers running HP-UX.
    >
    > Also, if you were to use caliper to
    > profile the system you could see or not see the checksum routines
    > being called and consuming non-epsilon quantities of CPU time.
    >
    > rick jones
    > --
    > denial, anger, bargaining, depression, acceptance, rebirth...
    > where do you want to be today?
    > these opinions are mine, all mine; HP might not want them anyway...
    > feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...


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