{"id":11887,"date":"2019-01-30T11:08:21","date_gmt":"2019-01-30T13:08:21","guid":{"rendered":"https:\/\/made4it.com.br\/netflow-configuration-on-juniper-routers\/"},"modified":"2023-03-09T14:56:07","modified_gmt":"2023-03-09T17:56:07","slug":"netflow-configuration-on-juniper-routers","status":"publish","type":"post","link":"https:\/\/made4it.com.br\/en\/netflow-configuration-on-juniper-routers\/","title":{"rendered":"Netflow Configuration on Juniper Routers"},"content":{"rendered":"\n

Hello<\/p>\n\n

Today we will break down how to configure your Juniper router to export Netflow (jFlow). At the end of the article is the configuration using IPFIX (Netflow v10).<\/p>\n\n

Here we have the Network topology and the Netflow Server information<\/p>\n\n

\"\"
Netflow topology and information<\/figcaption><\/figure>\n\n

These are the steps needed to configure a Juniper Router to export Netflow v5<\/p>\n\n

  1. Configure the NTP Server<\/li>
  2. Configuring Forwarding Options with Sampling Rate<\/li>
  3. Configure the Host that will receive the Flows coming from the Router<\/li>
  4. Configure the interface to enable Netflow on the interface<\/li><\/ol>\n\n

    Let’s go to the step-by-step configuration<\/p>\n\n

    1. Configure the NTP Server<\/li><\/ol>\n\n

      It is important to configure an NTP Server because the Flows data uses timestamp according to the router’s time. If the router has a different time than the server, the data will not agree with the time, generating a mismatch of information.It is important that you configure at least 2 NTP servers and also your router’s timezone.<\/p>\n\n

      ## Using the Servers of the a.ntp.br and b.ntp.brset system ntp server 200.160.0.8set system ntp server 200.189.40.8## Setting the Time-Zoneset system time-zone America\/Sao_Paulo## Default way to view the Juniper configurationguilherme@vMX-BGP> show configuration systemsystem {    time-zone America\/Sao_Paulo;  ntp {  server 200.160.0.8;  server 200.189.40.8;  }}<\/pre>\n\n
      2. Configure Forwarding Options with the Sampling Rate<\/p>\n\n
      The sampling rate to avoid overloading the CPU of your Routing Engine, it creates a sample of the traffic and exports it, so the Netflow system can receive the data and apply a multiplication factor to make the data real numbers.To configure, use the commands. The ideal value of the rate depends on how much traffic you use, a tip is important is to use values above 200 and analyze the CPU of your router.<\/p>\n\n
      ## Applying the Rate value to 500set forwarding-options sampling input rate 500## Juniper display form without display-setforwarding-options {  sampling {  input {  rate 500;  }<\/pre>\n\n
      3. Configure the Host that will receive the Flows coming from the Router<\/p>\n\n
      To configure your router to export Netflow it is necessary to inform it which IP address the server will receive the flows and which UDP port it will receive this traffic on.To do this use the commands:<\/p>\n\n
      ## Exporting to IP 192.168.210.47 on port 2055 and using netflow version 5set forwarding-options sampling family inet output flow-server 192.168.210.47 port 2055  set forwarding-options sampling family inet output flow-server 192.168.210.47 version 5## Show Preview without display setguilherme@vMX-BGP> show configuration forwarding-options  sampling {  family inet {  output {  flow-server 192.168.210.47 {  port 2055;  version 5;  }  }  }  }<\/pre>\n\n
      4. Configure the interface to enable Netflow on the interface<\/p>\n\n
      After setting the sampling rate and the flow server it is still necessary to activate Netflow on the interfaces where it will generate the data. Remember that it is necessary to configure the command inside each unit.To do this, configure the interfaces inside each unit with the following command:<\/p>\n\n
      ### Apply the sampling input command  set interfaces ge-0\/0\/1 unit 0 family inet sampling input<\/pre>\n\n
      The complete configuration looks like this:<\/p>\n\n
      guilherme@vMX-BGP> show configuration | display set  set system time-zone America\/Sao_Paulo  set system ntp server 200.160.0.8  set system ntp server 200.189.40.8 set interfaces ge-0\/0\/0 description \"Talk to Netflow  set interfaces ge-0\/0\/0 unit 0 family inet address 192.168.210.49\/24 set interfaces ge-0\/0\/1 description \"WAN INTERFACE - IP TRANSIT  set interfaces ge-0\/0\/1 unit 0 family inet sampling input  set interfaces ge-0\/0\/1 unit 0 family inet address 200.200.200.1\/30 set forwarding-options sampling input rate 500  set forwarding-options sampling family inet output flow-server 192.168.210.47 port 2055  set forwarding-options sampling family inet output flow-server 192.168.210.47 version 5## Juniper Show Shapeguilherme@vMX-BGP> show configuration  Last commit: 2019-01-30 13:30:01 BRST by guilherme  version 17.1R2.7;  system {  host-name vMX-BGP;  time-zone America\/Sao_Paulo;  ntp {  server 200.160.0.8;  server 200.189.40.8;  }  }  interfaces {  ge-0\/0\/0 {  description \"Talk to Netflow\";  unit 0 {  family inet {  address 192.168.210.49\/24;  }  }  }  ge-0\/0\/1 {  description \"WAN INTERFACE - IP TRANSIT\";  unit 0 {  family inet {  sampling {  input;  }  address 200.200.200.1\/30;  }  }  }  }  forwarding-options {  sampling {  input {  rate 500;  }  family inet {  output {  flow-server 192.168.210.47 {  port 2055;  version 5;  }  }  }  }  }<\/pre>\n\n
      To make it even easier we have the video demonstrating the configuration of each command applied in this tutorial<\/p>\n\n
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