What is an SNA Name?


I develop with an AS/400 and we're looking to upgrade to the iSeries IBM server and and apparently we're having some problems with the SNA Name (so I'm told).  The person working on this cannot resolve the SNA name to what it should be.  I looking for someone to give me their most detailed description of what an SNA name is and how it works, because there doesn't seem to be too much information on it via search engines.  We are working on implementing Enterprise Generation Language with Rational Business Developer as the developer client to replace COBOL.

I realize I haven't provided a lot of information on this, but I'm new to the subject, so any insight into what and SNA Name is and why it is affecting our transition so much would be greatly appreciated.

Thank you
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Gary PattersonConnect With a Mentor VP Technology / Senior Consultant Commented:
OK, first of all, the "IBM i" is just the latest name for the AS/400 operating system.  In the past the AS/400 was a dedicated hardware platform that ran the OS/400 operating system.  Now, IBM merged two hardware lines, the "i" line (running OS/400), and the "p" line (running AIX) into a single hardware line: the POWER hardware line.  For our purposes, when we talk about AS/400, OS/400, iSeries, iOS, or IBM i, we are really talking about the same basic operating system running on various generations of IBM midrange hardware.  

So for the purposes of our conversation, the AS/400 (OS/400) vs IBM i distinction is meaningless.

Here is the important part:  regardless of what you call it, (AS/400, OS/400, IBM i), it doesn't host VSAM databases.  I don't even know if any third-party products that might allow it to host VSAM databases.

VSAM is an IBM mainframe technology (Z-series hardware and OS - "big iron").  IBM mainframes are very different from AS400 systems.  They run on different hardware, use a different operating system, and are managed, programmed, and operated using (mostly) different tools and technologies.   There are no VSAM files on the AS/400 (or IBM i).  The AS/400 database is, and always has been, DB2.  

If you developer is connecting to VSAM files, then the odds are VERY STRONG that he/she is connecting to a mainframe to access them, not an AS/400.

Now, it is certainly possible for AS/400 (IBM i, whatever) programs to -remotely- access VSAM data on a mainframe.

So, perhaps it is possible that you have one or more AS/400 applications that access a remote VSAM database on (likely) and IBM mainframe someplace.
I suggest that you find someone that support the IBM mainframe that hosts the VSAM database, and enlist their assistance.  You should be able to log onto that system directly and access the VSAM file in question.  The mainframe support person may also be able to help you get your new debugger connected to the VSAM database.

VSAM: http://publib.boulder.ibm.com/infocenter/zos/basics/index.jsp?topic=/com.ibm.zos.zconcepts/zconcepts_169.htm

Is it possible that the problem is that the connection between the new IBM i system and the mainframe was lost in the conversion, and that is the real source of the problem?

If so, you'll, again, need to engage the assistance of the mainframe team to determine how to connect to the mainframe VSAM database.  

Is the old AS/400 system still available?  If so, it may be possible to harvest communications configuration information from there and transfer it to the new system.

- Gary Patterson
momi_sabagConnect With a Mentor Commented:
i'm not sure how as/400 works, but the mainframe works with a communication protocol called SNA (that was the only protocol in the past, now TCPIP is also supported)
SNA name is an identifier of an endpoint in that network (so it's kind of like an ip address + port)
Gary PattersonConnect With a Mentor VP Technology / Senior Consultant Commented:
"SNA" is a collection of proprietary IBM networking protocols.  SNA proprietary protocols provide similar functions to those served by TCP/IP protocols in most networks today.  It is also possible to tunnel SNA protocols over TCP/IP, and this is the most common way that SNA is used today: typically for compatibility with legacy devices and programs that depend on SNA, APPN, and APPC.

Odds are fairly good that this person is looking for the "APPN (Advanced Peer-to-Peer Network) name" for your system.  APPN names are made up of two components: a network name, and a system name.  In a SNA/APPN network, these two components are required to uniquely identify a specific host within a specific network.

NetworkID:     QUORUM (similar to a TCP/IP domain name)
System name: AS4001 (similar to a TCP/IP host name)

Use the green-screen command DSPNETA (Display Network Attributes) to display the APPN name components of your AS/400.

The SYSNAME parameter is the system hname/host name, and the LCLNETID is the name of the local APPN network that the system is part of.

If this doesn't give them what they need, post back with a detailed description of what your user is trying to do.  Please be very specific.

In particular, this information is typically needed when trying to establish connectivity from a PC program to the AS/400, or from some other APPN host system.  Note that for APPN connectivity to work, there has to be a network infrastructure in place capable of routing SNA/APPN network traffic (or systems need to be configured to tunnel SNA over TCP/IP - more common in recent years).

- Gary Patterson
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The person working on this cannot resolve the SNA name to what it should be.

Why would they need it at all?

That is, a big need could be that some other system needs to communicate with it through a SNA network connection. Just like a TCP/IP host name, a SNA connection needs either to know the correct SNA addressing or to resolve through a SNA networking node (similar to DNS resolution).

But if there is no SNA connection to(from) anything else, what is needing to be accomplished? What problem is bringing a need for knowing a SNA name?

Gary's suggestion of DSPNETA is the direct answer. But there might be an underlying problem that needs attention.

--TripWire--Author Commented:
Ok thanks - very helpful.
I just found out that we need to be able to allow access for SNA remote debugging on an IndexedRecord file, located on a server.  Do you happen to know of any online literature that could help us with that?  I'm sorry if this still isn't enough information, but I don't have that much to begin with.

SNA remote debugging

That's a slightly surprising request. Anyone involved in such a thing ought to be reasonably conversant in the subject.

But I take it that you are being asked by someone in your organization (or a consultant/contractor?) to assist at your local site. The remote site is using SNA (for some odd reason) and has no knowledge of how your iSeries works or has no authority to log on to it. So, you are being tasked with looking up info for them.

Has your system been configured to allow SNA over your network adapter? That is, is SNA actually in use on your iSeries?

...an IndexedRecord file, located on a server.

Are you needing a remote client to access the file on your iSeries? Or is your iSeries needing to access the file on a remote server? (A remote mainframe?)

Gary PattersonVP Technology / Senior Consultant Commented:
No idea what we are talking about here.  Can we narrow this down a bit?

Is you user trying to connect FROM the AS/400 TO another system (AS/400, Mainframe, PC, etc)?  
If so, what program, utility, or API are they trying to use?


Is your user trying to connect TO the AS/400 FROM another system (PC, another AS/400, a mainframe, etc?)
If so, what program, utility, or API are they trying to use?

In older versions of Rational Business Developer, (pre-version 8) the only mechanism for remotely debugging IBM mainframe (z/OS machine, not the AS/400 or iSeries) VTAM files was using a SNA connection, but this has nothing to do with the AS/400.  Are you sure your developer isn't confused about the target platform?


RBD does have an integrated debugger.  Here is a link to the RBD documentation:


- Gary Patterson

That's pretty much where I was heading. Knowing a SNA name is one thing; but if a developer is going in some strange direction due to an underlying misconception, things could get very confused.

I hoped to ensure that everything was going in a useful direction.

--TripWire--Author Commented:
We have an AS-400 that is being replaced by System i.

There is an error in a VSAM file from our old system.  Using our old COBOL debugger (IBM VisualAge Generator), we were able to take this file and edit it before.  However, we have now migrated our code to EGL, which does not support doing this.  Therefore, we need to find a way to be able to remotely debug this file and point it over to the new system.

The problem is, in order to do this, we need to have SNA setup.  My role in this project is purely research based.

If I am incorrect, and there is a way that we can still pull the file and debug locally, that would be preferable.

Hope that helps.
--TripWire--Author Commented:
Thanks for the info.  I already knew about the i and the 400 being essentially the same thing, I was only calling them by those names so that if I needed to distinguish between the two at some point in the conversation, you would know which I was referring to.  

Yes - The old 400 is still being used.  Can we assume that since we can connect to both systems, they can communicate with each other, or is there a specific IBM protocol that they're using?
Or is THAT in itself SNA?
Gary PattersonConnect With a Mentor VP Technology / Senior Consultant Commented:
You can connect to the AS/400 and/or i a lot of different ways.  

In recent years that connectivity has almost exclusively been over TCP/IP-based facilities.  For example, to get a green-screen terminal session, we typically connect using a flavor of Telnet called TN5250.  To establish a database connection, we typically connect using ODBC,  JDBC, etc. using TCP sockets.  The AS/400 supports dozens of TCP/IP facilities, both as a client and as a server: FTP, LPR/LPD, CIFS (Windows file sharing), HTTP, SSH, SSL, etc.

The AS/400, however, also supports SNA protocols for terminal (and PC terminal emulation) and printer connectivity, file transfer, and remote database connections, so without looking at your specific configurations, it is hard to guess.

Direct SNA communications, however, require special hardware support.  For example, many modern routers do not know how to route SNA traffic (or require special hardware or software to do so), so communicating between two different networks requires either a direct connection (leased line) between the two sites,  a dial-up connection(!), special support on -all- of the intermediate network devices between the two endpoint systems, OR it requires that SNA traffic be tunneled over TCP/IP connections, or perhaps the use of some intermediate gateway like the ancient MS SNA Server product.

There is nothing to stop you from using both communication stacks (TCP and SNA).  

It isn't terribly uncommon, for example, to use TCP/IP for most of your routine communications (terminal emulation, web-based applications, client/server database access, etc.), but to have a one or more  special-purpose SNA conections to older systems, or to IBM mainframes.  Most common in mixed-platform shops that have both AS/400 and mainframe systems.

I just finished ripping out an ancient, expensive dedicated-line SNA connection for one of my AS/400 customers after converting an APPC application to use SFTP over the Internet.  The short little project paid for itself almost instantly in communications cost savings.

Anyway, you can't make any assumptions about what can talk to what.  It all depends on how the machines are configured, how security is configured, where, from a network perspective the systems are related relative to each other and to the client systems, and other variables.

This is not a simple topic, and if your shop doesn't have in-house communications staff familiar with diagnosing problems with SNA communications (assuming that SNA is actually in use), you may need to bring in some outside help to trace the root of the problem.

- Gary Patterson

Check out my EE profile:  http://www.experts-exchange.com/M_4382324.html
tliottaConnect With a Mentor Commented:
As some mainframe developers begin working in AS/400 environments, the seem to tend to refer to native physical/logical files as "VSAM". The three main record-oriented forms of VSAM data sets can map fairly well to keyed, relative and sequential physical/logical files.

I would then expect that the file in question is simply an externally-described keyed PF or LF defined with DDS. Terminology is just creating some confusion.

Gary PattersonVP Technology / Senior Consultant Commented:

"SNA" + "VSAM" certainly makes me think "mainframe", though.  I suppose anything is possible, though.

- Gary

No disagreement, though this is said to be a conversion from what previously accessed a file on the AS/400 to EGL that will access (a copy of?) the same file on the iSeries.

Now, it's complicated by the "remote support" aspect. An odd part is that in the past couple years or so I've seen multiple "VSAM" mentions in "AS/400" contexts. As near as I can tell, almost all of those have come from consultants/contractors out of India or similar.


That's not intended to be a negative judgment. It simply comes from terminology differences. I wouldn't be surprised if some Indian technical institutes used VSAM to describe the underlying structure of DB2 on AS/400s.

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