#ACTIVE TIMER WHEN USING NETFLOW INSTALL#
#ACTIVE TIMER WHEN USING NETFLOW SOFTWARE#

The IP address of the collector and the destination port must be configured on the router or switch itself. NetFlow datagrams are exported using User Datagram Protocol (UDP). Both sensors can be enabled on the same machine at the same time, so that a single collector can receive and report on data from both NetFlow versions. For a router using NetFlow 9, one would need the NetFlow V9 Sensor. For example, to monitor a Cisco router using NetFlow 5, one would need to use the NetFlow V5 Sensor in PRTG Network Monitor.

#ACTIVE TIMER WHEN USING NETFLOW SOFTWARE#

The collector software must support the same NetFlow version as the exporting server. The collector is a different server or computer running a NetFlow receiver software designed to gather, record, filter, and analyze the resulting flows, such as PaesslerвЂ™s PRTG NetFlow Analyzer. NetFlow data is periodically reported to a NetFlow collector. It contains, among others, the version number for the packet, the system uptime (in milliseconds), a sequence number and the Source ID. The packet header is basically the same as in Version 5. Rather than pre-defining in a specification what data is coming and where, that definition is done within the packet itself. This is what allows for the extensibility of the record. The template FlowSet provides a description of what is coming in the data FlowSets. The record format is defined by a packet header, followed by at least one template FlowSet and data FlowSet. That means that future enhancements can be accommodated without having to change the basic flow record. The Version 9 flow record is template based. According to Cisco, standard NetFlow exports use about 1.5 percent of the total analyzed switched traffic.

Each datagram consists of up to 30 flows. NetFlow exportДЇlows are grouped for export into a NetFlow Export datagram. The NetFlow cache is checked every second by default. Data is expired and then exported from the cache to a NetFlow collector server at regular intervals based on flow timers. A flow record is kept for each active flow. This data is condensed into aВ database within the network deviceВ called the NetFlow cache. Monitoring and grouping every packet forwarded by a router or switch generates a lot of data. Sampled flows significantly reduce the performance impact when sending flow information. This is for use on routers where examining every packet is impractical due to volume of traffic. High-end Cisco routers support sampled NetFlow where only one out of a certain number of packets is examined. Any variation in the value of any one of the parameters creates a new flow.

Each additional packet with the same parameters (source and destination IP, address, source and destination port, class of service) is grouped into a single flow. A flow is generated by the first packet passing through the standard switching path. These sets can be configured based on matching attributes in each packet including:ДЄs each packet is forwarded, the above attributes are examined. IPFIX is often referred to as NetFlow v10 because it is based on NetFlow v9, but actually it is not NetFlow.ДЄ flow is a way ofВ grouping a unidirectional stream of packetsВ into a specific set. This version is preferred for IETF IP Information Export (IPFIX) WG and IETF Pack Sampling WG (PSAMP) and works with both IPv4 and IPv6. As such, it allows for expanded support without necessitating a change to the flow-record format. Version 9 is the current version and is template-based.

Version 8 has support for when router-based NetFlow aggregation is used. Version 7 added support for Cisco Catalyst switches using hybrid or native mode. Version 6 is no longer supported and was not released widely. It added Border Gateway Protocol information and flow sequence numbers to NetFlow Exports.

#ACTIVE TIMER WHEN USING NETFLOW INSTALL#

Version 5 is still commonly used today, because of a large existing install base of Cisco routers and switches released while it was the standard version. Versions 2 through 4 were internal versions, no public implementation was ever released. The original NetFlow version 1 is considered obsolete, and seldom used today. However, several versions were released only internally or were never widely implemented beyond specific hardware. There are technically ten different versions of NetFlow.

Active timer when using netflow