SNMP message size

By default, the interface does not group multiple requests for information into a single SNMP GetRequest message. The PDU (Protocol Data Unit) that PI Interface for SNMP sends to a network device contains a GetRequest for a single OID. The size of such a message is approximately 80 octets.

The size of a GetResponse PDU from the network device depends on the OID value requested, and can vary greatly. For example, the value for system.sysDescr.0 returned by the network device might be a descriptor such as the following:

IOS I 3600 Software (C3660-DS-M), Version 12.0(5)T1, RELEASE SOFTWARE (fc1)
Copyright I 1986-1999 by cisco Systems, Inc.
Compiled Thu 19-Aug-99 18:15 by cmong

The preceding value consists of 213 octets. With the addition of the various SNMP, UDP, and IP headers, the size of the complete message is about 280 octets.

When the interface retrieves numeric values, the size of the returned message is also about 80 octets. For comparison, a single Ping message from a Windows computer contains about 64 octets.