On Thursday, 11/15/2007 at 05:28 EST, "Spracklen, Ken" <[EMAIL PROTECTED]>
wrote:
> I think part of my confusion came from reading section 4.3 of the Linux
> for IBM System z9 and IBM zSeries redbook and mis-interpreting the
> paragraph regarding the hipersockets not using LAN frame, instead they
> are addressed by data queue addresses. I guess I read too much into it
> and that I took that to say that the mac address and ip address are no
> longer part of that data stream and that the ip stack knew that
> destination by an internal device address instead of ip address and did
> not use normal ip routing. Did I read it incorrectly and is the network
> layer info (dest ip address etc) still in the frame of data? So that a
> network concentrator like Linux on z/OS just needs to change the frame
> protocol to go out the appropriate interface much a like a router
> supporting token ring and Ethernet.
This is a case of the authors knowing just enough to be dangerous. :-)
People like to talk about How It Works when it comes to HiperSockets and
OSAs. (Who can blame them?) Unfortunately you get incomplete and
sometimes (often?) inaccurate information about the mechanism, but no
information on what happens between source and destination (because the
person doesn't know). I don't mean for this to sound Zen, but I would say
that HiperSockets works exactly as it must in order to accomplish the
goals set before it:
- Create an in-box isolated LAN segment sharable among and within LPARs
- Enable z/OS OSA<->HiperSockets concentrator
- Enable Linux flavor of the same thing ("HiperSockets accelerator")
Because the interface to HiperSockets is not published, I am unable to go
into any details about the interface. In my previous post I tried to
describe the *bevhavior* as best I could.
> It looks like I need to give it more thought to determine just how many
> Linux guest will want hipersocket access to z/os data. It may not be
> worth the effort to configure a hipersocket guest lan for the the Linux
> guests to connect into, just save on real hipersocket addresses.
You know those recent posts about QIOASSIST? You will want to pay
attention to them as they apply to dedicated HiperSockets connections,
too.
Alan Altmark
z/VM Development
IBM Endicott
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