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SNMP Enhancements



Networking enhancements for SNMP simplify application and firewall configuration for IBM i 7.1 and later releases.


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Recent networking enhancements to SNMP for IBM i 7.2 and 7.1 allow application and firewall configuration simplification. SNMP will now send responses via UDP port 161 instead of a random ephemeral port, simplifying firewall configuration. SNMP also now supports GetBulk requests, which provide an easier method for an application to retrieve a large amount of data. The ability to configure storage pool and disk unit block sizes will enable an SNMP manager to calculate an accurate size for large storage pools and disk units.  

Using the SNMP GetBulk request for data retrieval is a feature article which explains this topic in technical depth, including example usage. That article gives more detail about the following SNMP enhancements:

Sending responses via Port 161
In the past, IBM i would receive SNMP requests via UDP port 161 and then send a response via a random ephemeral port. This made it difficult to configure firewalls and still allow SNMP traffic to flow between an IBM i SNMP agent and an SNMP-based system or network management application running remotely. The SNMP agent has been changed so that responses to SNMP requests will now be sent via UDP port 161. Traps that originate on an IBM i partition will now also be sent via port 161.

Configuring storage pool and disk unit block sizes
As system storage sizes, with regard to both storage pools and individual disk units, have increased, the limits of the original SNMP design have been reached and sometimes exceeded. The size that SNMP returns for an 8 TB storage pool on an IBM i partition could show up as a negative number in some system management application, or it could be flagged as not valid. The latest enhancements to SNMP now allow the configuration of large block sizes that are used for returning storage size information for both storage pools and disk units. Configuring a larger block size with the Change SNMP Attributes (CHGSNMPA) command will now eliminate negative storage size values and prevent disk units being flagged by system management applications.

SNMP GetBulk request
Simple Network Management Protocol (SNMP) provides a system or network management application with the ability to gather information about network devices and to monitor them. To accomplish this, SNMP defines a set of operations for retrieving and setting data, as well as monitoring for conditions being reported by the devices. One of these operations, GetBulk, provides an application with the ability to easily retrieve a large amount of data with a single request. This can be particularly useful when retrieving information from one of the standard SNMP tables.

Requirements for code levels
IBM i 7.2 - PTFs SI55537, SI55539, SI55766, SI55787, and SI55966
IBM i 7.1 - PTF SI55745

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Document Information

Modified date:
09 January 2020