Knowledge Base

How to set up traffic monitoring with PRTG for various infrastructures

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This article explains the various options you have to monitor the network traffic that occurs inside LAN or that goes over a shared Internet connection or leased line.

With PRTG's three data acquisition technologies and the various infrastructure options in use today it can sometimes get complicated to decide which monitoring technology is right for your problem.

The easiest configuration is to monitor the local traffic of one PC by installing PRTG directly on it. This scenario is used to monitor a single PC in a LAN network or to monitor a PC connected to the Internet via DSL, modem, or cable (see: A0).

 

For other network configurations the following table use the following table to find your situation or task and follow the corresponding instructions below.

Step 1: Select Your LAN infrastructure
  Network switch, router or other device with SNMP support Router with Netflow support Managed switch with monitoring port option (or a hub) Unmanaged switch or router
Technology SNMP NETFLOW Packet Sniffing Packet Sniffing
Step 2: Choose what to monitor
Option I: Centralized LAN Traffic Monitoring
Total Network Traffic O A2 A3 O
Traffic per PC B1 B2 B3 O
Traffic per IP or protocol O C2 C3 O
Option II: Monitoring just one PC on which PRTG runs on
Traffic of local PC D1 O D3 D3
Traffic per IP or protocol O O E3 E3
Option III: Monitoring usage of a shared Internet connection or leased line
Total Leased Line Traffic F1 O O O
Traffic per PC, IP or protocol O G2 G3 O

A0: Monitoring Network traffic for a single PC connected to the Internet via DSL, cable, or a modem

  • Simply create one new Packet Sniffer sensor and select the PC's network card during the "Add Sensor" wizard and you will get the total network traffic
  • If you need traffic information for specific IPs or protocols apply a filter based on the corresponding IP/port for each item you want to monitor
  • Or (with PRTG V5 or later): If you do not need long term accounting data and only want to know the current and recent traffic by IP or protocol, you can create just one Packet Sniffer sensor and enable the Toplist feature based on IP or protocol.

A2: Monitoring Total Network traffic with Netflow

  • Configure Netflow protocol on the router to send Netflow packets to the computer running PRTG (see corresponding knowledge base article)
  • (Purchase and) install Netflow Collector License (also works with trial license)
  • Configure a Network collector in PRTG
  • Create a new Netflow sensor without any filtering to monitor network's total traffic
  • Note: If you have several switches/routers you may not see all traffic if you only monitor one device

A3: Monitoring Total Network traffic using a switch with monitoring port

  • Using a switch that has a "monitoring port" or "port mirroring" you can then monitor all the traffic in your network. Most unmanaged switches do not have this feature, many managed switches do.
  • Port mirroring is used on a network switch to send a copy of all network packets seen on one switch port to a monitoring network connection on another switch port. This is commonly used for network applicances that require monitoring of network traffic, such as an intrusion-detection system. Port mirroring on a Cisco Systems switch is generally referred to as SPAN.
  • BTW: You can also use an old fashioned hub. Hubs send all network packets to all ports, but they are of course a lot slower that switches
  • Configure the switch(es) to send a copy of all network packets to the IP of the machine running PRTG
  • Create a new Packet Sniffer Sensor without any filtering to monitor network's total traffic
  • Note: If you have several switches/routers you may not see all traffic if you only monitor one device

B1: Monitoring Network traffic of each PC (or connection) in a network using a switch/router with SNMP support

  • Enable SNMP on the switch or router or device and also set the security feature to allow PRTG to access the device
  • For windows PC install generic SNMP software from Windows CD (see corresponding knowledge base article)
  • It is a good idea to note down which PC (or device or leased line etc.) is connected to which port for later reference
  • Start the "Add Sensor" wizard, choose SNMP, enter the IP and the SNMP login data of the router/switch
  • In the checkbox list check the ports that you want to monitor and finish the wizard
  • Now you will get graphs of traffic of each device that is connected to one of the ports of your device
  • It is a good idea to double click each sensor in the sensor list and edit the sensor name with name of the actual connection
  • If you have several switches/routers/devices you must repeat this procedure for each device until you have created a sensor for each port )

B2: Monitoring Network traffic for each PC (or connection) with Netflow

  • Configure the Netflow protocol on the router to send Netflow packets to the computer running PRTG (see corresponding knowledge base article)
  • (Purchase and) install a Netflow Collector License (also works with trial license)
  • Configure a Netflow collector in PRTG
  • Create one new Netflow sensor for each PC to be monitored and apply a filter based on the IP of each PC you want to monitor
  • Or (with PRTG V5 or later): If you do not need long term accounting data for each PC and only want to know the current traffic by IP, you can create just one Netflow sensor and enable the Toplist feature.
  • Note: If you have several switches/routers you may not see all traffic if you only monitor one device

B3: Monitoring Network traffic for each PC using a switch with monitoring port

  • See A3 for monitoring port basics
  • Configure the switch(es) to send a copy of all network packets to the IP of the machine running PRTG
  • Create one new Packet Sniffer sensor for each PC to be monitored and apply a filter based on the MAC address or IP of each PC you want to monitor
  • Or (with PRTG V5 or later): If you do not need long term accounting data for each PC and only want to know the current and recent traffic by IP, you can create just one Packet Sniffer sensor and enable the Toplist feature based on IP.
  • Note: If you have several switches/routers you may not see all traffic if you only monitor one device

C2: Monitoring network traffic by IP address or protocol with Netflow

  • Configure the Netflow protocol on the router to send Netflow packets to the computer running PRTG (see corresponding knowledge base article)
  • (Purchase and) install a Netflow Collector License (also works with trial license)
  • Configure a Netflow collector in PRTG
  • Create one new Netflow sensor for each IP or protocol to be monitored and apply a filter based on the IP or protocol for each item you want to monitor
  • Or (with PRTG V5 or later): If you do not need long term accounting data for each PC and only want to know the current and recent traffic by IP or protocol, you can create just one Netflow sensor and enable the Toplist feature based on IP or procotol.
  • Note: If you have several switches/routers you may not see all traffic if you only monitor one device

C3: Monitoring network traffic by IP address or protocol using a switch with monitoring port

  • See A3 for monitoring port basics
  • Configure the switch(es) to send a copy of all network packets to the IP of the machine running PRTG
  • Create one new Packet Sniffer sensor for each IP/protocol to be monitored and apply a filter based on the corresponding IP/port for each item you want to monitor
  • Or (with PRTG V5 or later): If you do not need long term accounting data for each PC and only want to know the current and recent traffic by IP or protocol, you can create just one Packet Sniffer sensor and enable the Toplist feature based on IP or protocol.
  • Note: If you have several switches/routers you may not see all traffic if you only monitor one device

D1: Monitoring Network traffic for a PC running PRTG using SNMP

  • Install and enable generic SNMP software from Windows CD (see corresponding knowledge base article)
  • Set the security feature to allow PRTG to access the device
  • Start the "Add Sensor" wizard, choose SNMP, enter the local PC's IP and the SNMP login data
  • In the checkbox list check the ports (which correspond to the network cards in this case) that you want to monitor and finish the wizard
  • Now you will get graphs of traffic of each network card

D3: Monitoring Network traffic for a PC running PRTG using Packet Sniffing

  • Create one new Packet Sniffer sensor for each network card to be monitored

E3: Monitoring Network traffic for a PC running PRTG using Packet Sniffing

  • Create one new Packet Sniffer sensor for each IP/protocol and for each network card to be monitored and apply a filter based on the corresponding IP/port for each item you want to monitor
  • Or (with PRTG V5 or later): If you do not need long term accounting data for each IP or protocol and only want to know the current and recent traffic by IP or protocol, you can create just one Packet Sniffer sensor and enable the Toplist feature based on IP or protocol.

F1: Monitoring total Network traffic of a shared Internet connection or leased line using a switch/router with SNMP support

  • Enable SNMP on the switch or router or device and also set the security feature to allow PRTG to access the device
  • Find out which port (i.e. port number) the shared connection is attached to
  • Start the "Add Sensor" wizard, choose SNMP, enter the IP and the SNMP login data of the router/switch
  • In the checkbox list check the box of the port the shared connection is attached to and finish the wizard
  • Now you will get a graph of traffic of the shared linee

G2: Monitoring network traffic by IP address or protocol of a shared Internet connection or leased line Monitoring with Netflow

  • See C2, but select filtering to exclude the LAN IPs

G3: Monitoring network traffic by IP address or protocol of a shared Internet connection or leased line Monitoring with Packet Sniffing

  • See C3, but select filtering to exclude the LAN IPs

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