Dennis
I spotted SNA in your post so I figured I should know something about what
the post was about - but I'm left with barely a clue. Is DLC some new
shorthand for something other than what DLC has traditionally meant,
namely Data Link Control, the 2nd layer of the Open Systems
Interconnection (OSI) model?
Well, I did quite a bit of research - it saves so much time when the original
post is s bit clearer about the subject! - and I discovered the Microsoft DLC
driver. Indeed Microsoft's DLC appears to be a building block in constructing
communication between some Microsoft programming, presumably BizTalk in
this instance, and something else. Microsoft's DLC is an implementation of
IEEE 802.2 Logical Link Control (LLC).
The IEEE 802.2 is the key, specifically the connection-oriented version. It
implies communication over a LAN, typically Ethernet or Token Ring. I assume
there is some higher level software, maybe Microsoft's Host Integration Server
(HIS), which supports higher level SNA protocols so that, minimally - and
perhaps maximally - Low Entry Networking (LEN) is supported. Thus an LU
supported by say HIS can be in SNA session with another LU in a node
supporting the same or equivalent protocols over the same, potentially
segmented - including DLSw - LAN.
I was very amused to see DLC being described as a non-routed protocol.
Well, it is by definition - Duh!
If you are concerned about what you would require on the mainframe, today
it would be an OSA feature configured to be able to support a VTAM External
Communication Adapter (XCA) major node definition - like the old 3172 if you
ever had one of those. You can review what types of OSA feature might be
suitable from the following:
http://www.redbooks.ibm.com/abstracts/tips0088.html
You need to look for Yes in the SNA/APPN/HPR traffic column.
Do not be put off by APPN and HPR. For LEN support, you need only the
traditional subarea flavour of VTAM which you probably still maintain on each
of your LPARs minimally as a stand-alone VTAM in order to support TSO if
nothing else - a stand-alone VTAM just as it used to be in the mid to late '70s
when I first got to know VTAM - before it became a program product!
If it comes to it and you need help configuring it - if the documentation
advising how to use their IP-DLC (Enterprise Extender to the rest of the
world) from Microsoft is anything to go by, you *will* need help - please post
again in the fullness of time.
Thinking this through a bit, if the Microsoft DLC is an option in order to
support BizTalk then their IP-DLC (Enterprise Extender) should also be an
option. This is very much du jour for SNA support in an IP-centric world.
However, you *would* need to enable your VTAM for APPN (and HPR) in this
case.
Anyone aware of any stated DLC direction (like it's going away soon)?
I see no reason why the use of the OSA for SNA traffic could be heading for
the sunset. OSA features supporting the OSE (SNA-supporting) flavour of
CHPID seem to be being added from time to time to that Technote I
referenced. You will, of course, attract some anti-SNA bigots with an appeal
such as this. Be sure that any advice given has documentation from IBM
behind rather than simply being a warped opinion.
Chris Mason
On Tue, 24 Mar 2009 11:48:02 -0700, Longnecker, Dennis
dennis.longnec...@courts.wa.gov wrote:
I've got a vendor coming in wanting us to enable DLC so 'BizTalk can talk to
the mainframe'. I'm thinking like DLC is such old technology and we've
deinstalled all the SNA gateways/etc. in favor of TCP/IP types of connections.
Anyone aware of any stated DLC direction (like it's going away soon)? I'm
concerned that I've got a vendor coming in proposing technology that just
isn't current.
Thanks,
Dennis
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