Streaming telemetry with gNMI

This document describes how you can set up a lab environment for testing gNMI using a virtual HPE Juniper router running Junos 24.2 R1-S2.5. It shows how you can collect metrics for interfaces and CPU utilization collected with OpenNMS. This isn’t something I do every day, so I just preserve this here for my future self and the ones who want to get up to speed a bit quicker.

What you will learn

• Enable gNMI over gRPC with sensors on a HPE Juniper router
• Verify the gRPC connections and configuration
• Enable OpenNMS Horizon to subscribe to gRPC streams for sensor data
• Set up TLS on gRPC using a self-signed certificate authority
• Visualize the collected data in Grafana

Limitations

• Streaming telemetry can only be configured from the OpenNMS Core instance, see enhancement NMS-18064
• Metric labels for network interfaces are right now just resource id strings

Before you begin

You need the following environment to get a lab running:

Hackathon on BGP monitoring using BMP in OpenNMS

We have seen people in the OpenNMS chat who started playing with the BGP monitoring protocol. I had some notes in our MediaWiki which doesn’t exist anymore. To provide some background I’ve resurrected my notes and republished the content. I had to tweak a few places to make it a bit more current. During the 5 years, OpenNMS has fixed bugs and maintained the functionality. The main intention of resurrecting the article is to give people some insights and background on what approach was chosen and why things are as they are today.

UDP tuning and performance testing

Problem statement

• Ingesting UDP traffic is complicated to measure
• Packet drops, connectionless and unreliable
• Measuring on ingest on the network interface card
• How can you make sure you measure reasonably?
• You want a method to create some confidence how many UDP packets your system drops

Create a lab environment to reproduce the problem

• Make the problem visible using with overloading a small device Raspberry Pi 3
• Use sysctl default settings
• Use something like hping3 or iperf to create a overload situation

You can’t improve what you don’t measure

• Show tools like dropwatch or ss -lump or SNMP udp metrics to visualize packet drops
• Compare packets received with tcpdump vs. iperf
• Theory should show who be tcpdump should have more but not all then the sender

Increase buffers size?

• What happens if you increase the buffer size?

Use PF_RING

• How does the behavior change when you use PF_RING with TCPDUMP

Conclusion

This website is not available in your country

Note to my future self. You might find yourself in a situation where you are blocked from an internet service because of your geographic location. A way to get around is using a VPN from a friend in a non-evil geographic location or using a 3rd party VPN service. Sometimes you don’t have that option right away and you need something quickly - Torbrowser for the rescue.

Download and install the latest Torbrowser. Edit the torrc file and set a strict exit node from a country of your choice.

BGP monitoring playground

Monitoring BGP can be done in various ways. First thing people want to know is if there is a way to get notifications in case a BGP peering session goes down. A pretty common way monitoring the BGP peering session state is using SNMP and the RFC1269 MIB. In OpenNMS Horizon we have the BGP session monitor which allows to track the state using the BGP peer table. The downside is, you need to configure for every peering session a monitor and this can be cumbersome and hard to maintain.

Mac OS X and DHCP is screwing your Host Name

I’m using Mac OS X with iterm2, oh-my-zsh and spend 75% of my time in those terminals. It is totally annoying to me if I connect to a DHCP network and it screws up my hostname. Especially when I’m used to looking at the prompt which tells me the host I’m connected to.

It is possible to fix your computer name for several things using the scutil command which requires administration permissions. I’ve found a link to the Mac OS X Server Worksheet which explains a few things in more detail. Here is what I did to prevent my computer changing the host name.

Zyxel vs. Vodafone Easybox with VDSL 50

I ran in some trouble with my Vodafone Easybox 904 xDSL. Even with 2Ghz and 5Ghz WLAN I had regularly drops. Had to turn on / off the WLAN on the device or had to reboot it to reconnect. Otherwise the VDSL line reguarly got disconnected, also replacing the Easybox from Vodafone didn’t helped, so I bought a Zyxel VMG1312-B30A.

IPv6 and Monitoring

We are all happy when we are able to get IPv6 connectivity for our new servers. In case the network is provided by someone else and some kernel settings you can get in some tricky situations.

With IPv6 there are so many addresses your Laptop and Mobile can have a unique public IPv6 address forever - pretty cool huh? The downside is, it would be pretty easy to trace every connection you ever do back to your device - this really not what you want! When you provide a service this behavior is not so useful. Otherwise there are several ways to autoconfigure your IPv6 configuration, beside DHCPv6 the interesting one is stateless address configuration.