The information in this article applies to:
- Microsoft SNA Server for Windows NT, versions 2.11 and 3.0
SUMMARY
When the SNA Server client software initializes (Wnap.exe for Windows 3.x,
or Snabase.exe for Windows 95, Windows NT and MS-DOS), it opens a "sponsor"
connection to SnaBase running on an SNA Server in the subdomain. This
article describes how the SNA client locates a sponsor server.
NOTE: The order that computers running SNA Servers are tried for 3270, LUA
or LU6.2 sessions is not affected by the sponsor server chosen by the
client. For information about SNA Server load balancing and hot backup, see
the following Microsoft Knowledge Base article:
ARTICLE-ID: Q128244
TITLE : SNA Server Load Balancing and Hot Backup
MORE INFORMATION
The client locates a sponsor server as follows:
- If Named Pipes or TCP/IP is configured on the SNA client, and the client
is configured as local to the server(s), the client sends a broadcast
to the subdomain and waits for a response from a server-side SnaBase
service. The first SnaBase to respond to the client's request will be
tried for the sponsor connection.
NOTE: If the server is located on a different TCP/IP subnet than the
client, this broadcast is normally filtered by any intermediate IP routers
separating the client and server. In this configuration, the remote
connection method should be chosen during SNA client setup.
- If the SNA Server 2.11 Service Pack 1 (or later) client software is
being used on Windows 3.x, Windows 95 or Windows NT, the client will
randomly choose a server from this list. However, the SNA Windows 3.x
and Windows NT clients (and the Windows 95 client, with an update to
SNA Server 3.0 post-SP1) can be configured to try servers in the order
they're configured, by setting the RandomSponsor setting documented
below. The MS-DOS client doesn't support TCP/IP sockets. When named
pipes is chosen, the MS-DOS client tries the remote servers in order
and never randomly chooses the sponsor server.
NOTE: The SNA client Setup programs only prompt for two remote server
names. To configure additional remote servers, they can be manually added
for the Windows 3.x, Windows 95 and Windows NT clients as follows:
- Windows 3.x client: Add server names preceded with \\ on the
Remote= line in the [WNAP] section of Win.ini, separating the server
names with spaces. When connecting over TCP/IP, the server's IP address
may be specified explicitly. For example:
Remote= \\server1 \\server2 \\124.55.69.45
- Windows 95 client: add server names to the following registry value,
separated by spaces, but *not* prepended with \\. For example:
HKEY_LOCAL_MACHINE/Software/Microsoft/SnaBase/Parameters:
Sponsors: server1 server2 server3
- Windows NT client: add server names to the following registry value
(servers must be listed on separate lines):
HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/
SnaBase/Parameters
Sponsors: REG_MULTI_SZ: server1
server2
server3
- If NetWare IPX/SPX is configured on the SNA client, and the client is
configured as local to the server(s), the client queries the NetWare
bindery based on the subdomain name entered during SNA client setup.
The server-side SnaBase service automatically registers with the NetWare
bindery, specifying the SNA subdomain name and a SAP service type of
0x444. The client retrieves all SNA Server computers from the bindery,
and then randomly chooses a server.
- If NetWare IPX/SPX is configured on the SNA Windows 95 or Windows NT
client, and the client is configured as remote to the server(s), the
client queries the NetWare bindery looking for the specific server names
specified during SNA client setup. The server names are stored in the
registry as described earlier. The server-side SnaBase service
automatically registers with the NetWare bindery and specify their
subdomain name and a SAP service type of 0x444. The client locates the
servers in the bindery, and then randomly chooses a server.
NOTE: When connecting over Banyan or NetWare IPX/SPX, the SNA Server
Windows 3.x client only supports local connection mode described earlier.
- If Banyan Vines is configured on the SNA Windows 95 or Windows NT
client, the client queries the Banyan StreetTalk directory service based
on the StreetTalk list name (that is, subdomain name) entered during SNA
client setup. The server-side SnaBase service automatically registers
with StreetTalk, creating a StreetTalk List based on the subdomain name,
and a PC-based Service for each SNA Server. The client retrieves all SNA
Server computers from the StreetTalk List, and then randomly chooses a
server.
The sponsor connection must be successfully established before an SNA
application session (that is, 3270, LUA, APPC, CPIC, CSV, and so forth)
will connect to an SNA Server.
Background on the Sponsor Connection
When the SNA Server client software initializes, it opens a "sponsor" (or
service) connection to the SnaBase service on an SNA Server in the
subdomain. The following functions are performed over this sponsor
connection:
- The client is notified of SNA Server computers running in the subdomain.
- The server responds to various client requests, including requests for
3270 user/group records.
- When connecting over TCP/IP sockets, NetWare IPX/SPX or Banyan Vines,
the SnaBase service performs a Windows NT domain log on for the client.
- The client notifies the server of any autostarted invokable TPs that
are registered on the client computer. The server sends dynamic load
requests to the client when an attach request is received, if the
invokable TP is configured on the client.
- The client reports errors to the server, to write to the Windows NT
application event log.
The RandomSponsor Setting
The SNA Server 2.11 Service Pack 1 (or later) client software implements
random selection of a sponsor server if Named Pipes or TCP/IP is configured
with the remote option. The initial release of SNA Server 2.11 and
previous versions of the SNA client software will open remote sponsor
servers in the order configured.
By randomly choosing a sponsor server, the SNA Windows 3.x, Windows 95
and Windows NT clients will tend to load balance across SNA Servers for
their sponsor connection to help distribute the load across servers.
The RandomSponsor setting can be configured for the Windows 95 client after
applying SNA Server 3.0 Service Pack 2. If this Service Pack is not
applied, remote sponsor servers are always tried in random order.
The RandomSponsor setting is enabled by default for Windows 3.x, Windows
NT, and Windows 95 clients but can be disabled through the following
configuration setting:
SNA Server Windows 95 Client
If the SNA Server 3.0 Service Pack 2 Windows 95 client is applied, the
following entry may be set:
HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/SnaBase/Parameters/
RandomSponsor: 0
SNA Server Windows 3.x (or WFW) Client
In the [WNAP] section of Win.ini:
RandomSponsor = NO
SNA Server Windows NT Client
HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/SnaBase/Parameters/
RandomSponsor: REG_DWORD: 0
The client SnaBase service must be restarted to implement this change.
Disabling the RandomSponsor setting causes the SNA client to try the remote
servers in the order they're configured.
Keywords : prodsna snawin3x snawin95 snawinnt kbfix3.00.sp2 kbnetwork kbtshoot kbusage kbfaq
Version : 2.11 3.0
Platform : WINDOWS
Issue type : kbinfo