On Tue, Jun 28, 2005 at 04:48:17PM -0400, David Kreuter wrote: > > Is this possible: > 10.1.1.x host in Real Switch; Real Switch turnk port via OSA to Vswitch > in LPAR A with linux host 10.1.1.19; same linux host has a hipersocket on > 1.2.3.4 with VLAN enabled connecting to a linux host in LPAR B at 1.2.3.5 > with VLAN enabled. Linux host on LPAR A with VLAN enabled configures > 10.1.1.29; linux host on LPAR B with VLAN enabled configures 10.1.1.39. > So now a packet can journey from 10.1.1.39 to real host 10.1.1.19 over > hipersocket over LPARa's OSA??
I read this wrong first up. I'm pretty sure now that you just want to get from A to B via the Hipersockets rather than the OSAs. That's not too difficult actually; it's a SMONR[1], and after that a SMOR[2]. :) Whenever you're dealing with multi-homed hosts, you have the problem of getting the kernel to choose the right interface for the job (this is a problem not unique to Linux, or mainframes). You know Linux on LPAR A by 10.1.1.19; from Linux on LPAR B, if you use that address you go over the OSA -- not what you prefer. You need to use 1.2.3.4 as a destination, but that's not the address that's stored in DNS for Linux on LPAR A. Your proposal of trying to get the Hipersockets to look like part of the LAN is fraught with danger. Don't look at doing that. You would need to look at the Linux Ethernet bridging code, and quite apart from whether it is actually possible to bridge an Ethernet to a Hipersockets, there is massive potential to cause real problems on the LAN environment. The better approach is just to use the right destination IP address. The easiest way to do that would be to add each of the Linux guests to each others /etc/hosts file, using the Hipersockets IP address. If you've got a number of hosts attached to the Hipersockets though, this might get messy; a different approach would be to define a second hostname in DNS for each system. Clients on the LAN say "ssh lparA-linux", you (from Linux on LPAR B) say "ssh lparA-linux-hipers" (for example). For the really adventurous, you could set up your own DNS in the mainframe Linux environment. That way you could have your own IP address mappings. This only works well if your Linux systems are in their own DNS zone (because you don't want to have to keep your own copy of everything else in the same DNS zone). There are other DNS tricks that can be done though; BIND 9 has ways to provide different information depending on where the request came from, which would be a creative way of addressing the issue. VIPA can help the name resolution problem too. By using a virtual address as a destination, the best way to reach that address from any given host is determined by routing. This works best when a dynamic routing protocol is used, so that everyone learns the best path to the virtual address from wherever they are. Unfortunately the amount of cycles that our typical routing daemons consume makes them an unattractive proposition for large installations. > I know as an alternate I can do this by connecting both using a shared OSA > port on LPAR A and LPAR B - but - I need all the justification I can muster > for a hipersocket solution - A shared OSA certainly would relieve you of the multihoming issues that using a Hipersockets creates. It obviously doesn't give you all of the Hipersockets goodness though, and the issues of multihoming really are not so significant that you should have to give up on using Hipersockets. > Don't ask - network planner at client site does not want to introduce "new > subnets or networks" - vswitching into z/VM LPARS is fine - Then just be vewwy vewwy qwiet... :) You could use an arbitrary IP subnet (like an RFC1918 private range -- if your company is using 10/8, then pick something from 172.16/12 or 192.168/16) and don't try and advertise it or use it as a backup routing path or anything else. The systems attached to the Hipersockets will be the only systems that ever need to know about it. Of course I'd never *really* advocate doing such a thing, but it could be a way to get an official network from the planners quick-smart ;) Cheers, Vic Cross [1] Simple Matter Of Name Resolution [2] Simple Matter Of Routing ---------------------------------------------------------------------- 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
