On Thursday, 06/05/2008 at 05:14 EDT, "Martin, Terry R. (CMS/CTR) (CTR)" 
<[EMAIL PROTECTED]> wrote:

> Basically once I got the filename correct and added the PASSWORD for the 

> TCPMAINT 198 disk I was able to get the OBEYFILE command to work. I did 
receive 
> an error on my first good try. It was balking about the MTU size being 
invalid. 
> I was using 16384. I changed it to 1500 and tried the OBEYFILE command 
again 
> and it worked.
> 
> I noticed on the NETSTAT displays that the MTU actually was 32768 with a 
Frame 
> Size of 4096. I used a HIPERSOCKETS device that was GENed with 
CHPARM=40. So 
> basically it did not use the MTU size that I had defined in the PROFILE 
TCPIP.

CHPARM=40 is a MFS of 24K, not 4096.  The MTU = MFS - 8K, so the MTU is 
16K.  (Doc'd in the IOCP book.)

Be sure everyone using the same HiperSocket chpid has the same MTU.  If 
you don't, a PING will work, but a large data transfer won't.

Alan Altmark
z/VM Development
IBM Endicott

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