There was a post a couple of weeks ago (sorry, don't remember the
author and can't find the original post) that strongly
recommended enabling checksumming for TCP in NMMGR. I considered
doing this until I saw the following "Help" information in NMMGR:

Checksum enabled (Y/N)

     Specifies whether or not checksumming will be enabled in the
     local configuration. Checksumming causes significant
     overhead and is not normally needed for this protocol;
     therefore, HP recommends the default value (N) for this
     field unless communication to a non-HP machine is desired.
     (Note that checksumming may be done anyway if determined by
     the destination path report in the network directory or by
     the values specified in the NetIPC intrinsics, IPCCONNECT
     and IPCRECVCN.) Default Value: N Range: Y or N

What concerns me is the "significant overhead".  We've been
running with a TCP/IP network for over 3 years with no indication
of database corruption problems. The system is a 987/200 with
approximately 500 concurrent users and heavy transaction rates.
We see indications that we are approaching ever closer to the
knee of the performance curve.

Of those who have enabled checksumming, has it had a significant
impact on performance? With TCP/IP controlling packet sequencing
and Ethernet controlling collision processing, doesn't this make
it less important to validate the data with checksum processing?

Thanks in advance for your comments.

Steve Barrett

    Steven P. Barrett
    Systems Analyst
    Fairfax County Public Library
    e-mail:  [log in to unmask]

    --- The opinions expressed here are mine alone. ---

    "Life is dear to every living thing, the worm that
    crawls upon the grownd will struggle for it."
    (from Solomon Northup's - Twelve Years a Slave, at -
    http://metalab.unc.edu/docsouth/northup/northup.html)