On Wednesday, 11/14/2007 at 06:00 EST, "Spracklen, Ken" <[EMAIL PROTECTED]> wrote:
> Recently we started planning for Linux guests to access data on the z/os > lpars via hipersockets. As part of that process, we defined a new > hipersocket, IUTIQDEF, to the z/VM TCPIP guest profile and added the > IUTIQDEF device to the OSPF config for MPROUTE (same subnet as the > IUTIQDFF interface). We then created a new guest lan (glan01 with type > hipersocket and used nicdef/couple commands for a Linux guest and the > TCPIP guest to use that hipersocket guest lan. > > The problem is that I could not ping the ip address of z/VM IUTIQDEF > interface from the zOS systems nor ping the hsi1 ip address on the Linux > guest. A q lan glan01 det indicated both guests connected but the TX/RX > counts were 0 and the discards were high. If you draw the picture Rob requested, you will see that a Guest LAN is a separate subnet and needs to be attached to your existing network using the same techniques as you would for a real LAN segment. > 1) Is the above scenario possible or recommended? We are hoping to use > the guest lan concept to conserve on real hipersocket devices needed for > Linux guests. Does routing work the same way (via the a lookup table) > for a hipersocket guest lan as it does on a real hipersocket network? It is fine, though you may wish to give Linux OSA Guest LAN (QDIO or Hipersocket) is not a bridge or switch. It is a LAN segment that requires routing. > 2) Would the above scenario work if the new guest lan was configured as > QDIO? Is there much savings in cp cycles and memory by using a > hipersocket guest lan vice a qdio guest lan? That depends on the workload. The z/VM Performance Reports, going back to z/VM 4.3, provide a comparison of QDIO vs. HiperSockets. > 3) In the documentation we have encountered, we have seen examples of a > z/OS hipersocket concentrator and a Linux network concentrator. Does > someone have an example of a z/VM TCPIP/MPROUTE concentrator? Can z/VM > TCPIP/MPROUTE support routing between hipersockets, osa's, and guest lan > (hipersockets and/or qdio)? Which type of concentrator is recommended? z/VM does not provide a HiperSocket concentrator (i.e. a HiperSocket Virtual Switch). > 4) In the scenario of the z/os hipersocket concentrator, the z/os is the > router and there are a few Linux guests attached to the hipersockets. I > was wondering if someone could clear up my understanding how that Linux > guests can route data to an ip address out on the network beyond z/os > tcpip. In my foggy mind, I can see the Linux guest indicating the > default route is out the hipersocket interface, but if the hipersocket > frame doesn't have the LLC info like the ip address of the destination, > how does z/os know what ip address to put into the destination ip > address so that goes out into the "normal" lan network? Or is my > understanding of hipersockets incorrect about the LLC headers It's not a "routing" thing. Linux thinks the same-subnet IP addresses on the OSA network are local and does what Linux normally does: sends the packet directly to the intended IP address, not via a default route. A miracle occurs in Step 2 and z/OS gets the packet, unchanged, and places it on the LAN. In return, z/OS has responsibility to handle ARP issues on the OSA on Linux's behalf. To the rest of the network, z/OS and all of the Linuxen have the same MAC address. Alan Altmark z/VM Development IBM Endicott ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
