Thanks Alan! Thank You, Terry Martin Lockheed Martin - Information Technology z/OS & z/VM Systems - Performance and Tuning Cell - 443 632-4191 Work - 410 786-0386 [EMAIL PROTECTED]
-----Original Message----- From: The IBM z/VM Operating System [mailto:[EMAIL PROTECTED] On Behalf Of Alan Altmark Sent: Friday, August 22, 2008 9:11 AM To: IBMVM@LISTSERV.UARK.EDU Subject: Re: HiperSockets Question On Wednesday, 08/20/2008 at 09:54 EDT, "Martin, Terry R. (CMS/CTR) (CTR)" <[EMAIL PROTECTED]> wrote: > After a lot of effort we found that there was an extra route in the > Linux routing table that sent the data bound for one of the z/OS LPARS > over to our z/VM where it then was routed by the TCP/IP stack on z/VM to > the z/OS LPAR over the HiperSockets LINK. This LINK happened to have a > MTU size of 1500. When we removed the bogus route from the Linux routing > table causing the SQL queries in question to travel over a HiperSockets > LINK with a MTU size of 16348 they were successful. It appears that the > difference in the MTU sizes was the problem. > > My question is does the MTU size mismatch cause the problem? I thought > that even if the packets were fragmented they would still get over in > full. Yes, it can (but not always) cause a problem if the MTU sizes on the same shared media are different. All MTUs on the same network segment need to have the same MTU. Alan Altmark z/VM Development IBM Endicott
