I refer to our position as on the perf site. that is what I consider
official as those are the recommendations of the perf team based on real
tests. as I wrote in the other post.
I'll quote again:

"TCP/IP Window Size


Use the Tivoli Storage Manager option TcpWindowSize 63 on both the Tivoli
Storage Manager Windows NT client and Tivoli Storage Manager Windows NT
server. Since Windows 2000 supports TCP window scaling, it may be
beneficial to use a larger TCP window size for Windows 2000 systems that
are communicating exclusively with other Windows 2000 or UNIX systems."





Why?


Because the maximum tcpwindowsize WITHOUT RFC 1323 (scaling windowsize
support) is 65535 bytes, that's 64KB -1. TSM option tcpwindowsize 64 means
64*1024 or 65536 - one byte too big if the client doesn't support RFC 1323.
win2000 does support rfc1323, but you have to set a registry entry to take
advantage of it. the tcp windowsize sets the SO_RCVBUF option on the socket
connection, which is the size of the total data buffered on the connection.
MS docs say this size needs to be a multiple of the MTU for best results,
but this is basically garbage.  For standard Ethernet MTU of 1500 bytes,
the difference in the number of packets that can be buffered between 63KB
and 64KB is a nit. There is a difference between saying 64KB and meaning
65535 bytes.





this does not mean that you can't put the parameter to 64 and actually see
an improvement. I gave a general answer. I would be more careful with
absolute assertions in this field.


I'm somewhat disturbed that a certified TSM consultant is not aware of
this.







Cordiali saluti
Gianluca Mariani
Tivoli TSM Global Response Team, Roma
Via Sciangai 53, Roma
 phones : +39(0)659664598
                   +393351270554 (mobile)
gianluca_mariani AT it.ibm DOT com



                      Mark Stapleton
                      <stapleto@BERBEE.        To:       ADSM-L AT VM.MARIST 
DOT EDU
                      COM>                     cc:
                      Sent by: "ADSM:          Subject:  Re: optimising 
tcpwindowsize and tcpbuffsizes
                      Dist Stor
                      Manager"
                      <[email protected]
                      .EDU>


                      10/07/2002 15:35
                      Please respond to
                      "ADSM: Dist Stor
                      Manager"





From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On Behalf Of
Gianluca Mariani1
> TCPWINDOWSIZE should be set to 63 on Win2k.

>Cordiali saluti
>Gianluca Mariani
>Tivoli TSM Global Response Team, Roma

You need to check your documentation. Windows 2K machines should have
TCPWINDOWSIZE set to 64 (assuming 10 or 100Mb Ethernet).

I'm somewhat disturbed that a member of the Tivoli TSM Global Response Team
isn't aware of this.

--
Mark Stapleton (stapleton AT berbee DOT com)
Mark Stapleton (stapleton AT berbee DOT com)
Certified TSM consultant
Certified AIX system engineer
MCSE