CISCO-TN3270SERVER-MIB

MIB Reference — IPNetwork Monitor · Updated September 09, 2026

All MIBsCISCO-TN3270SERVER-MIB

Organization: Cisco Systems, Inc.

Last Updated: 1997-01-22

Category: Cisco Devices, SNA and Legacy Protocols, Web and Application Servers

Description: Manages TN3270 server functionality enabling TCP/IP-connected terminals to access IBM mainframe applications.

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What Is CISCO-TN3270SERVER-MIB?

CISCO-TN3270SERVER-MIB manages the TN3270 Server feature on Cisco routers, a gateway function that lets TCP/IP-connected terminals and PCs access IBM mainframe applications using the 3270 protocol over SNA. It builds on the standard PU/LU MIB from RFC 1666 and adds Cisco-specific detail on IP-to-LU (Logical Unit) and LU-to-IP mapping, connection listener statistics, and physical unit (PU) status. For monitoring purposes it is valuable for tracking software-level service health: global statistics such as tn3270sStartupTime (effectively an uptime/start indicator for the service), current versus maximum LU pool utilization (tn3270sLusInUse against tn3270sMaxLus), per-listener TCP port and idle-timeout/keepalive configuration, and PU/LU session mapping state. It explicitly depends on the IETF PU/LU MIB defined in RFC 1666 for its base session-management model. It is deployed on Cisco access routers acting as SNA-to-IP gateways in enterprises still running legacy IBM mainframe applications accessed by modern IP-based terminal emulators, and a CISCO-TN3270SERVER-MIB download is the usual starting point for adding this visibility to an NMS.

IPNetwork Monitor allows you to monitor SNMP objects defined in CISCO-TN3270SERVER-MIB. Use the built-in SNMP Monitoring Browser to explore available variables, view their current values and descriptions, and select the objects you want to monitor. You can then create SNMP monitors, configure thresholds, and receive alerts when monitored values change.

Supported Devices

  • Cisco routers (SNA/TN3270 gateway feature)
  • Cisco IOS devices bridging IP terminals to IBM mainframes

Monitoring Examples

An operator would poll tn3270sGlobalTable/tn3270sGlobalEntry (indexed by tn3270sIndex) to read tn3270sLusInUse versus tn3270sMaxLus, watching for the pool approaching exhaustion as new terminal sessions are refused. tn3270sGlobalTcpPort, tn3270sGlobalIdleTimeout, and tn3270sGlobalKeepAlive show the listener's configured behavior, while tn3270sGlobalUnbindAction indicates how sessions are torn down. tn3270sStartupTime lets an admin confirm how long the TN3270 service has been running on a given router, flagging an unexpected recent restart as a possible fault.

What Can Be Monitored

  • logical unit (LU) pool usage vs. maximum
  • TN3270 service startup time / uptime
  • listener TCP port and idle timeout settings
  • keepalive configuration
  • PU (physical unit) status
  • IP-to-LU and LU-to-IP session mappings
Imported Objects

From CISCO-SMI

ciscoMgmtOBJECT-IDENTITY

From SNMPv2-CONF

MODULE-COMPLIANCE
OBJECT-GROUP

From SNMPv2-SMI

Counter32
Gauge32
IpAddress
MODULE-IDENTITY
OBJECT-TYPE

From SNMPv2-TC

DisplayString
MacAddress
TEXTUAL-CONVENTION
TimeStamp
TruthValue

How to Use in IPNetwork Monitor

Example using tn3270sStatsConnectsIn OID:

Select a Cisco router (SNA/TN3270 gateway, legacy) as the target host to create a monitor — the SNMP service should be up and running on it. Click New Monitor, then check SNMP Custom on the Favorites tab, click Next, and confirm the host. On the next page, click Select... to open the built-in SNMP MIB Browser and type tn3270sStatsConnectsIn into the Find box to locate it in the OID tree, selecting the specific row/instance you want to monitor since this is a table column, then select it and click OK. It reports the total number of TN3270 session connects-in received. On the monitor's Main parameters page you can set the target's SNMP port (default 161), credentials, polling interval, and other settings — see the SNMP Monitor help for details. On the State conditions and Alerting tabs, configure when the monitor should change state and trigger an alert; since this is a Counter32-type OID, Value bounds is the most useful condition here — trigger an alert if the counter increases sharply between polls relative to its normal baseline, since an unexpected spike often reflects a real change in traffic or activity. Click Finish to create the monitor; you can adjust any parameter later.
OIDs

RFC description

Manages Cisco TN3270 terminal emulation server with IP-to-LU mapping and session statistics.

Start monitoring Cisco routers (SNA/TN3270 gateway, legacy) with a free 30-day trial of IPNetwork Monitor. Import MIBs, browse SNMP OIDs, create custom SNMP monitors, configure alerts, and monitor any SNMP-enabled network device from a single console.

Download CISCO-TN3270SERVER-MIB