Both ports are the same, and can be used for generic Ethernet traffic. If at all possible, you want to avoid going through the z/VM TCP/IP stack. VSWITCH is what allows you to do this, and it gives you a nice throughput increase with a reduction in CPU overhead. It also allows you to conserve those device numbers and assign them to things that really need them, such as MVS or VSE. When using VSWITCH, traffic that is going from one guest to the other never leaves the box, or even hits the OSA card for that matter. Even if you don't use VSWITCH, the traffic would go from one guest to the OSA card, and then to the other guest without ever going outside the box.
Mark Post -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Tom Duerbusch Sent: Monday, January 31, 2005 12:31 PM To: [email protected] Subject: OSA getting me up to speed We are looking at new hardware, and most likely it will include OSA adapter(s). Now, before I spec things out wrong, I would like to understand how they are used and their limitations. Currently, we have IBM 3172(s). 1 Ethernet card = 1 IP address. In this type of environment, I dedicate the Ethernet card to VM's TCP/IP and have it act as a router to my 9 VSE and 17 Linux images, each having their own IP address. My understanding is the OSA card has a dual port card. Can both ports be used for standard, generic Ethernet IP stuff? Not talking SNA over IP or anything else, just standard IP (LPR, TN3270, FTP, Database, Web, etc). Each card has lots of IP addresses associated with them. That translates to bunches of CUA (mainframe addresses). I could see, giving each of the guests their own address, directly to the card, instead of being routed through VM's stack. Is that normal? Or is that mostly for "special" guests, such as those that may operate outside of the firewall? If two images need to talk to each other, the traffic would end up going out on the wire...right? Doesn't seem to be a "performance" option. I could also see connecting the images, with Guest LAN support (not all my VSE images support Guest LANs), which would solve the 'going out on the wire' problem' for those that can use it. Is the recomendation to mix and match? Route everything though a central stack for routing? Give each image their own access? Other? Just what does all of you that use OSA cards do with all those IP addresses? Is the OSA cards, sharable across LPARs? What I'm looking for is IFL and S390 LPARs. >From the mainframe side, I'm pushing for redundent access. If the network doesn't support it, it's not my area, but it will be upgraded in time. Points will also be given for items (good or bad) concerning redundency. There are 2 gb OSA 2 Express cards. If cost isn't an issue, I don't see why we wouldn't go with the best. But in other shops, is the network side ready for 2 gb Ethernet? I have all these manuals, Redbooks and other documentation. They tell me all sorts of things (some are z/OS only, I think), but I'm having a hard time understanding how they work in the real world (VM, VSE and Linux). Thanks Tom Duerbusch THD Consulting ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
