The Netflow MIB provides a simple and easy method
to get NetFlow cache information, current NetFlow
configuration and statistics. It will enable medium to
small size enterprises to take advantage of NetFlow
technology over SNMP at a reduced infrastructure cost.
The MIB is created to provide Netflow information in
1. Cache information and configuration.
2. Collector information and configuration.
3. Export Statistics.
4. Version 9 Export Template information.
A flow is defined as a unidirectional sequence of
packets with some common properties that pass
through a network device. These collected flows
are exported to an external device, the NetFlow
collector. Network flows are highly granular;
for example, flow records include details such
as IP addresses, packet and byte counts,timestamps,
Type of Service (ToS), application ports,
input and output interfaces, etc.
A device (for example, a router) with NetFlow
services enabled. The exporter monitors packets
entering an observation point and creates flows out
of these packets. The information from these flows
are exported in the form of Flow Records to
A Flow Record provides information about an IP Flow
that exists on the Exporter. The Flow Records are
commonly referred to as NetFlow Services data or
The NetFlow Collector receives Flow Records from
one or more Exporters. It processes the received
export packet, i.e. parses, stores, display the
Flow Record information. The flow records may be optionally
aggregated before being stored into the hard disk.
NetFlow Version 9 Export format is template based.
Version 9 record format consists of a packet header
followed by at least one or more template or data
FlowSets. A template FlowSet (collection of one or more
template) provides a description of the fields that
will be present in future data FlowSets. Templates
provide an extensible design to the record format,
a feature that should allow future enhancements to
NetFlow services without requiring concurrent changes
to the basic flow-record format.
One additional record type is also a part of
Version 9 specification: an options template. Rather
than supplying information about IP flows, options are
used to supply information about the NetFlow process
configuration or NetFlow process specific data.