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This is a new category of article that falls under "RARE software architecture" special blog series. As its name implies, it deals with topics related to RARE/freeRouter software / Monitoring.


  • Basic Linux/Unix knowledge
  • Service provider networking knowledge


In Greek mythology, Prometheus is a Titan that is credited mankind creation by stealing Fire from Gods and by giving it to human. In the RARE context, Prometheus is a the software from project. It became very popular in the IT industry as it is very simple to implement/configure while providing a great number of metrics without impacting application performance. It is heavily used in microservices environment such as docker and Kubernetes. The mythological reference gives us an indication of how Prometheus is operating. At a constant rate, Prometheus metric collector or server is stealing metrics from Prometheus agent. All the stolen metrics are then consolidated in Time Series database ready to be poured to a queueing system for proper visualization. 

Before going further, allow me a brief digression by sharing with you a small anecdote that leds to this ongoing work related to network monitoring for RARE. As mentioned previously, our focus is to elaborate RARE/freeRouter solution the possibility to be monitored in an operational environment. In that context, we started with the implementation of a lightweight SNMP stack that provided relevant result via SNMP tools like LibreNMS. This is great for organisation that wouldn’t want invest time on anything but SNMP.

However, we felt a lack of flexibility due to SNMP inherent structure and we needed more versatile and instant monitoring capabilities.  More importantly the need to export infinite metric type from Control Plane in a more flexible way arise. How metrics such as: Number of IPv4/IPv6 routes, IPv4 BGP prefix, IPv6 BGP prefix platform JVM memory etc. could be shared without too much hassle ?

After some internal discussion, I just said: "I’m not a monitoring expert but we have tools like ELK and PROMETHEUS and GRAFANA in NMaaS catalog … Shouldn’t we consider use this ?"

The answer was: « Let’s give it a try and fire up a Prometheus and Grafana instance from NMaaS platform !»

Some hacking at the control plane code level were initiated, after few hours freeRouter lead developer came up with a solution and said: Let me introduce you "freeRouter prometheus agent »

And thanks to the great support of NMaaS team, in few minutes and some point and clicks (it took longer than expected as I’m not good with GUI) we were able to test this agent.

Why is it important you might say ? It is just that with prometheus simplicity and low resource overhead with have full control plane metrics visibility !

As a side note this is not a replacement for INT/Telemetry/Netflow/IPFIX that provide different type of data that are to at the same scale…
People with INT/TELEMETRY/NETFLOW/IPFIX are talking about a "data lake" or "data deluge". Which is correct, if you think about the complexity of resolving a  gigantic producer/consumer data problem. This needs the relevant IT infrastructure in order to process all of the data provided by these protocol at the NREN scale.

While in our case, we are just focusing on exposing CONTROL PLANE METRICS at the network element level. We simply monitor and ensure a router operation by using prometheus metrics


While he above might be true, the number of metrics exported from a prometheus target can be very high. Fine tuning might be necessary in order to make sure that all metrics are really necessary for network monitoring purpose. This explosion of metrics exposure can add unnecessary workload at the control plane level. 

Again, kudos to NMaaS team that made this happen so that we could test this on the P4 LAB with — ZERO — effort.

Article objective

In this article, we will present freeRouter and Prometheus integration and as an example we will implement one of the 22 grafana dashboard that we developed and published here. In the rest of the article we will assume that you are a running one or more freeRouter nodes.


[ #001 ] - Cookbook

 Configure a Prometheus server

The first step is to implement a prometheus server. Using NMaaS it is pretty instantaneous. However, if you plan to deploy prometheus in an other platform just follow the installation guide here.

Once deployed you can push the following prometheus.yaml config:

  scrape_interval: 15s
  evaluation_interval: 30s
    - static_configs:
      - targets:
  - job_name: 'router'
    metrics_path: /metrics
    scrape_interval: 15s
    - targets: ['','']

In this configuration we assume that we have 2 freeRouters that are configured as above ( and in prometheus worls these are called targets:

  • each target are interrogated or "scraped" very "scrap_interval" which is 15s here
  • the main job name is called; "router"
  • metrics_path is: "/metrics" so the scraped URL is: "

Note that this had to be deployed only once for all of your routers. However, each time you'd like to add a new router, you have to add a new target in the "targets" YAML list.

 Configure Prometheus FreeRouter control plane

In this example let's focus our interest interface metrics. Please note that this configuration should be deployed on each freeRouter and connectivity should be available between all targets and the prometheus server.

The objective is to tell freeRouter control plane to expose hardware and software counter interface metric. In order to do this just copy/paste the stanza here below via freeRouter CLI:

prometheus interface metric configuration
server prometheus <PROMETHEUS_SERVER_NAME>
 metric inthw command sho inter hwsumm
 metric inthw prepend iface_hw_byte_
 metric inthw name 0 ifc=
 metric inthw replace \. _
 metric inthw column 1 name st
 metric inthw column 1 replace admin -1
 metric inthw column 1 replace down 0
 metric inthw column 1 replace up 1
 metric inthw column 2 name tx
 metric inthw column 3 name rx
 metric inthw column 4 name dr

 metric intsw command sho inter summ
 metric intsw prepend iface_sw_byte_
 metric intsw name 0 ifc=
 metric intsw replace \. _
 metric intsw column 1 name st
 metric intsw column 1 replace admin -1
 metric intsw column 1 replace down 0
 metric intsw column 1 replace up 1
 metric intsw column 2 name tx
 metric intsw column 3 name rx
 metric intsw column 4 name dr
 vrf <VRF_NAME>

So this basically means:

  • From freeRouter CLI, issue the following command:
prometheus interface metric configuration
sho inter hwsumm
interface   state  tx          rx          drop
hairpin41   up     67404       0           0
hairpin42   up     153134      0           0
sdn1        up     412319805   1057514903  1152305
sdn2        up     1038840147  407307558   202
sdn3        admin  0           0           0
sdn4        admin  0           0           0
sdn5        admin  0           0           0
sdn6        admin  0           0           0
sdn998      up     9154        0           0
sdn999      up     199178      262939      0
tunnel1965  up     0           9122896     0 
  • prepend to the metric name: "iface_hw_byte_"
  • column 0 will have prometheus label ifc=
  • replace all dots "." by "_" . (so interface bundle1.123 will become bundle1_123)
  • column defines a metric name  "iface_hw_byte_" concatenated to "st" => "iface_hw_byte_st" which is essentially interface status
  • if column 1 "state" value is admin/down/up we associate value -1/0/1 
  • column defines a metric name  "iface_hw_byte_" concatenated to "tx" => "iface_hw_byte_tx" which is essentially interface bytes transmitted counter 
  • column defines a metric name  "iface_hw_byte_" concatenated to "rx" => "iface_hw_byte_rx" which is essentially interface bytes received counter 
  • column defines a metric name  "iface_hw_byte_" concatenated to "dr" => "iface_hw_byte_dr" which is essentially interface bytes dropped counter 

And if you followed this correctly, we are repeating these lines for software interface counter metric.


You can view Prometheus configuration for various Grafana dashboard here. Feel free to study these Prometheus configuration and activate them as you see fit depending on your requirements. The set of dashboard is not exhaustive and is by no means absolute. Feel free to submit additional dashboard ! We would gladly add them in the current list of freeRouter Dashboard.


After this definition a freeRouter level you should have:

4 metrics related to hardware counters 

  • iface_hw_byte_st
  • iface_hw_byte_tx
  • iface_hw_byte_rx
  • iface_hw_byte_dr

4 metrics related to software counters

  • iface_sw_byte_st
  • iface_sw_byte_tx
  • iface_sw_byte_rx
  • iface_sw_byte_dr

Which is a total of 8 metrics


From that point you can check via prometheus console:

check the "Targets" menu drop down selection

From that point you should be able to use PromQL query filed in order to check that you can retrieve the metrics we defined above.

 Grafana configuration

For metric visualisation, we will use Grafana. Therefore:

  • install Grafana from official web site.
  • Once installed configure Prometheus as Grafana data source:


  • fill in all the prometheus server information

  • check the the data source is defined correctly by clicking the "Save & test" button

At that point your Grafana and Prometheus are correctly binded.

  • now you need to import "RARE/freeRouter interface bytes" dashboard

  • download freeRouter interface bytes dashboard here 

  • import the dashboard via ID or simply download JSON or use JSON panel

And Voila ! 

In order to immediately see the graph zoom in to 5m period with a refresh of 5s and you should see automagically the interface bytes TX/RX on all interface for each targets.


This example related to interface metrics is universal, as the metrics at freeRouter level are yielded through a generic CLI command:

  • "show interface hwsummary"
  • or "show interface swsummary".

However some metrics cannot be retrieved by generic interface. Some metrics will be tied to specificities of your network. These can be the AS number, IGP process name, VRF name etc.

Let me give you a couple of examples:

 the metrics below assume that you have deployed a link state IGP called: "isis 1" 

But your network context you could have arbitrary deployed "isis 2200". (2200 is RENATER AS number) 

prometheus interface metric configuration
 metric lsigp4int command sho ipv4 isis 1 interface
 metric lsigp4int prepend lsigp4_iface_
 metric lsigp4int name 0 proto="isis1",ifc=
 metric lsigp4int replace \. _
 metric lsigp4int column 1 name neighbors
 metric lsigp4peer command sho ipv4 isis 1 topology 2
 metric lsigp4peer prepend lsigp4_peers_
 metric lsigp4peer name 0 proto="isis1",node=
 metric lsigp4peer replace \. _
 metric lsigp4peer column 1 name reachable
 metric lsigp4peer column 1 replace false 0
 metric lsigp4peer column 1 replace true 1
 metric lsigp4peer column 6 name neighbors
 metric lsigp4perf command sho ipv4 isis 1 spf 2 | inc reachable|fill|calc|run
 metric lsigp4perf prepend lsigp4_perf_
 metric lsigp4perf labels proto="isis1"
 metric lsigp4perf skip 0
 metric lsigp4perf column 1 name val

 metric lsigp6int command sho ipv6 isis 1 interface
 metric lsigp6int prepend lsigp6_iface_
 metric lsigp6int name 0 proto="isis1",ifc=
 metric lsigp6int replace \. _
 metric lsigp6int column 1 name neighbors
 metric lsigp6peer command sho ipv6 isis 1 topology 2
 metric lsigp6peer name 0 proto="isis1",node=
 metric lsigp6peer prepend lsigp6_peers_
 metric lsigp6peer replace \. _
 metric lsigp6peer column 1 name reachable
 metric lsigp6peer column 1 replace false 0
 metric lsigp6peer column 1 replace true 1
 metric lsigp6peer column 6 name neighbors
 metric lsigp6perf command sho ipv6 isis 1 spf 2 | inc reachable|fill|calc|run
 metric lsigp6perf prepend lsigp6_perf_
 metric lsigp6perf labels proto="isis1"
 metric lsigp6perf skip 0
 metric lsigp6perf column 1 name val
 in the metric below the variable is BGP AS number "65535": 

prometheus interface metric configuration
 metric bgp4peer command sho ipv4 bgp 65535 summ
 metric bgp4peer prepend bgp4_peer_
 metric bgp4peer name 4 peer=
 metric bgp4peer replace \. _
 metric bgp4peer column 1 name learn
 metric bgp4peer column 2 name advert
 metric bgp4peer column 3 name state
 metric bgp4peer column 3 replace false 0
 metric bgp4peer column 3 replace true 1
 metric bgp4perf command sho ipv4 bgp 65535 best | exc last
 metric bgp4perf prepend bgp4_perf_
 metric bgp4perf replace \s _
 metric bgp4perf column 1 name val

 metric bgp6peer command sho ipv6 bgp 65535 summ
 metric bgp6peer prepend bgp6_peer_
 metric bgp6peer name 4 peer=
 metric bgp6peer replace \: _
 metric bgp6peer column 1 name learn
 metric bgp6peer column 2 name advert
 metric bgp6peer column 3 name state
 metric bgp6peer column 3 replace false 0
 metric bgp6peer column 3 replace true 1
 metric bgp6perf command sho ipv6 bgp 65535 best | exc last
 metric bgp6perf prepend bgp6_perf_
 metric bgp6perf replace \s _
 metric bgp6perf column 1 name val 
 Last example with "LDP null" metrics, in this particular case the variable object is the VRF name: "inet"
prometheus interface metric configuration
 metric ldp4nul command sho ipv4 ldp inet nulled-summary
 metric ldp4nul prepend ldp4null_
 metric ldp4nul name 3 ip=
 metric ldp4nul skip 2
 metric ldp4nul replace \. _
 metric ldp4nul column 0 name prefix_learn
 metric ldp4nul column 1 name prefix_advert
 metric ldp4nul column 2 name prefix_nulled

 metric ldp6nul command sho ipv6 ldp inet nulled-summary
 metric ldp6nul prepend ldp6null_
 metric ldp6nul name 3 ip=
 metric ldp6nul skip 2
 metric ldp6nul replace \: _
 metric ldp6nul column 0 name prefix_learn
 metric ldp6nul column 1 name prefix_advert
 metric ldp6nul column 2 name prefix_nulled 


In this 1st article, you were presented :

  • freeRouter/Prometheus integration 
  • How to add a new router in the list of Prometheus target
  • How to integrate a RARE/freeRouter Grafana Dashboard. (Feel free to adapt the other available dashboard query to your context !)

Final words

In Prometheus philosophy, normally the user should do only the minimum of tweaking regarding configuration. Ultimately, he should be only be able to enable a metric or simply disable it if the scrape cost is too high. However in freeRouter/Prometheus integration process, you see that some metric are issued using specific $variable (VRF, BGP/IGP process number ...) Which makes impossible to maintain this universality. However, from the network operator point of view this should not be a showstopper. On the contrary, it is a powerful choice to be able to alter these command via $variables.

Remember in freeRouter philosophy you can have multiple VRF, multiple IGP and multiple BGP process number ! (Which is not the case for all routing platform)

Last but not least, this Prometheus agent was developed quickly because of one reason, all the objects  at the control plane level were already well structured in table form as previously described in this article. So implementing this table row/column logic in order to derive a prometheus metric was technically possible without too much hassle.

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