A Tale Of Two Gateways: Bridging The Old And New
SNA Server is well-integrated with NT Server and provides a variety of monitoring tools and debugging aids. The NT Performance Monitor can even show 3270 Response Time Monitor data along with other gateway and server performance information (but AS/400 user-response time requires third-party tools, such as NetPerfector from Open Universal Software). The SNA Admin program shows connections to the host, LU pools and component status among other things. Microsoft SNA 2.11 administrators will like the new layout, which at first glance seems much like the previous version but is actually far easier to use. For example, the layout groups related areas for easy viewing.
 Host Connection Made Easy
Another n
oteworthy feature of Microsoft's SNA 3.0 is its SNA Wizards, which walk you through setting up connections to a mainframe or AS/400. IBM's goal with the AS/400 was to create a robust host that is power
ful, simple to use and easy to administer. Communications setup is friendlier than that of mainframe communications. Consequently, most AS/400 administrators have little exposure to traditional SNA terminology unless they work in a mixed mainframe-midrange environment--the jumble of PUs, LUs, exchange IDs and aliases can be very confusing. Microsoft's AS/400 Wizard let us make a connection to the host the first time, with well-chosen defaults for communications settings.
With the AS/400 AutoConfig option running on the host, we did not have to configure the gateway's Advanced Program-to-Program Communications (APPC) controller. The only drawback is that LU alias names/node names on NT SNA 3.0 are the same on an AS/400 host. This lack of unique naming makes ongoing administration difficult. Further customizat
ion is required to get unique node names.
As a bonus, 3270 and 5250 applets are included and can be run from the gateway for testing. Although some customers may try to run the applets from client PCs, the applets offer only basic terminal emulation and are not meant to be used as the primary client.
Microsoft developers have been busy in the area of host connectivity. SNA Server covers all the popular configurations and connectivity options that NetWare for SAA does, and adds some major options not found in Novell's product, such as direct bus/tag channel and Escon attachments to mainframes via an adapter in the PC server. Running at speeds of about up to 17 Mbps and 9 Mbps, respectively, Escon and bus/tag could provide great speed boosts compared to Ethernet or Token-Ring.
Novell does not endorse or support direct channel attach by NetWare for SAA, though it is available from a few third-party vendors. Mention "channel attach" as we did in a call to Novell technical support and you will get the aud
io equivalent of a blank stare.
With SNA Server you can remove an old 3174 terminal controller, buy a channel adapter card for the gateway, and plug in directly to the host, getting speeds far beyond what
a few Synchronous Data Link Control (SDLC) links to your mainframe front-end processor (FEP) could deliver. Also unlike Novell's SAA, Microsoft's product supports 3270 DFT and twinax links to the AS/400. For those who like the idea of trying to drive a truck through a keyhole, a variety of SDLC and Qualified Logical Link Control (QLLC) adapters are supported.
Talking With the Client
Microsoft SNA 3.0's other notable features--including comprehensive protocol support with encryption, single sign-on and password synchronization, host print, and AS/400 Shared Folders support--round out an impressive list.
SNA 3.0 supports encryption to the gateway of all data, not just passwords. One of the drawbacks of older versions of the AS/400 OS was that data encryption over network connections was not
available. In fact, even password encryption is still unavailable with many PC emulation products. Although not tested in our lab, with SNA 3.0, all data can be encrypted from the client to the server using the RC4 algorithm.
Much like Unix's Network File System (NFS), AS/400 Shared Folders let PC data be stored on the host. Previous versions of Shared Folders had a deserved reputation of being slow, but recent upgrades to this AS/400 facility, now called Integrated File System, have improved speed considerably and offer support for other file system types, including Unix. With SNA 3.0 Shared Folders support, client software is no longer required because Shared Folders can be mounted to the NT Server. This feature is absent in NetWare for SAA.
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