Router SNMP Interfaces & delta/rate with MQTT Output

Telegraf
1

I am trying to poll a Cisco router’s interfaces to get the current bit rate by polling the ifHCInOctets and ifHCOutOctets. This works fine and I get the numbers, however I want to get the delta between the last and current poll so I can see the current amount of traffic on the interface. I’ve tried processors and aggregators but nothing is working so far. Anyone have an idea how I can accomplish this? Thanks!

[agent]
  debug = true
  interval = "10s"
  flush_interval = "10s"
  omit_hostname = false
  round_interval = true

[[inputs.snmp]]
  agents = ["${ROUTER_IP}"]
  version = 2
  community = "${SNMP_COMMUNITY}"
  interval = "10s"
  agent_host_tag = "source"

  # Port-channel40
  [[inputs.snmp.field]]
    name = "po40_ifInOctets"
    oid = "IF-MIB::ifHCInOctets.61"
    conversion = "int"

  [[inputs.snmp.field]]
    name = "po40_ifOutOctets"
    oid = "IF-MIB::ifHCOutOctets.61"
    conversion = "int"

[[aggregators.basicstats]]
  drop_original = false
  namepass = ["po40_ifInOctets", "po40_ifOutOctets"]
  period = "10s"

# mqtt output
[[outputs.mqtt]]
  data_format = "json"
  protocol = "3.1.1"
  servers = ["${MQTT_SERVER}:1883"]
  topic = "router/${ROUTER_IP}"

This is the output I’m getting in MQTT:

{
  "fields": {
    "po40_ifInOctets": 26984590881118730,
    "po40_ifOutOctets": 19059662710492224
  },
  "name": "snmp",
  "tags": {
    "host": "61b9377503b1",
    "source": "10.15.11.14"
  },
  "timestamp": 1724182740
}
2

@mzac I think you are looking for the derivative aggregator…

3

Do you specifically need it stored this way in your database? We just add delta to our graph queries to solve this.

1 Like
4

When doing mqtt queries you can’t add delta to the query… it is very limited.

5

@mzac I don’t think I understand what you mean with

[…] you can’t add delta to the query…

Could you please detail a bit more on what exactly you want to do?