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
