> -----Original Message----- > From: The IBM z/VM Operating System > [mailto:[EMAIL PROTECTED] On Behalf Of Dennis Schaffer > Sent: Wednesday, August 02, 2006 12:27 PM > To: [email protected] > Subject: VM TCP/IP Routing Question > > > Hi, > > Our network folks noticed that one of our zLinux systems is > driving a lot > of packet retransmissions, caused mainly because packets are > being received > out-of-sequence, outside the target workstation's response > window (I hope > I'm getting the terminology correct here). > > Going one step further, the network folks say this is > happening because the > zLinux system (actually, this is probably VM TCP/IP, as I'll > explain in a > moment) is transmitting packets sort of round-robin across > both of our OSA > interfaces, rather than picking one interface and > transmitting all packets > across that interface. > > They've asked if we can tweak our configuration to send > packets across a > single adapter in order to reduce retransmissions. > > VM TCP/IP is involved because the zLinux system is connected > to a guest lan > which is connected to VM's TCP/IP stack. The zLinux system > has just one > logical ethernet interface but VM TCPIP is connected to both OSA > interfaces, via separate VSWITCH connections. Each of the > VSWITCH/OSAs is > attached to a separate IP subnet. > > Does anyone know if there's a TCP/IP or MPROUTE configuration > parameter > which can affect this behavior? > > Would this be more easily controlled using a zLinux TCP/IP > stack? We've > experimented with connecting a zLinux system to the VSWITCHs > directly and > using Zebra/OSPF in zLinux but didn't feel our traffic volume > justified the > increased management and automation requirements. But, maybe > this would > make it worthwhile? > > Thanks in advance for any help you can provide. > > Dennis Schaffer > Mutual of Omaha >
Look at ASSORTEDPARMS EQUALCOSTMULTIPATH at http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/HCSK5A20/24.5 it seems to describe what you are seeing. -- John McKown Senior Systems Programmer HealthMarkets Keeping the Promise of Affordable Coverage Administrative Services Group Information Technology This message (including any attachments) contains confidential information intended for a specific individual and purpose, and its content is protected by law. If you are not the intended recipient, you should delete this message and are hereby notified that any disclosure, copying, or distribution of this transmission, or taking any action based on it, is strictly prohibited.
