Category: network management
I hope you’re aware that the venerable ping (and most of its variants) measures round-trip-time – how long it takes to get to the destination and back – but is there a way to measure one-way latency or find out asymmetric transit times?
Ben Cox found a way to use ICMP timestamps together with reasonably accurate NTP-derived time to do just that. More details in Splitting the ping (HT: Drew Conry-Murray).
Remember my rant how “fail fast, fail often sounds great in a VC pitch deck, and sucks when you have to deal with its results”? Streaming telemetry is no exception to this rule, and Avi Freedman (CEO of Kentik) has been on the receiving end of this gizmo long enough to have to deal with several generations of experiments… and formed a few strong opinions.
Unfortunately Avi is still a bit more diplomatic than Artur Bergman – another CEO I love for his blunt statements – but based on his NFD16 presentation I expected a lively debate, and I was definitely not disappointed.
In early May 2020 I wrote a blog post introducing SuzieQ, a network observability platform Dinesh Dutt worked on for the last few years. If that blog post made you look for more details, you might like the Episode 111 of Software Gone Wild in which we went deeper and covered these topics:
- How does SuzieQ collect data
- What data is it collecting from network devices
- What can you do with that data
- How can you customize and extend SuzieQ
Imagine a life where you would be able to…
- Find all interfaces that have VRRP configured but no useful VRRP neighbor;
- Find all OSPF adjacencies that should be up but are not;
- Get an alert every time the default IP route is lost;
- Find all MTU mismatches in your network;
- List all VXLAN-to-VLAN mappings across your data center, and find if two different VLANs map into the same VXLAN VNI;
- Compare IP routes in your data center to those you had yesterday;
- Verify that IP routing tables on all spine switches contain the same prefixes;
- Do the same comparison before and after a software upgrade;
- Identify changes in IP routing tables or ARP tables that happened between yesterday evening and this morning;
… and be able to do all that in a multi-vendor environment without writing tons of Ansible playbooks or Python code.
Andrea Dainese is continuing his journey through open-source NetDevOps land. This time he decided to focus on log management systems, chose Elastic Stack, and wrote an article describing what it is, why a networking engineer should look at it, and what’s the easiest way to start.
Maybe it’s time to build our own network monitoring systems from open-source components instead of paying vendors big bucks for slick PowerPoint slides.
Supposedly it was a problem with the management network used by their optical gear, but it looks a lot like a layer-2 network spanning 15 data centers and no control-plane policing on the managed devices… proving yet again that large-scale layer-2 networks are a really bad idea.
I asked David Gee to review my streaming telemetry blog posts to make sure I didn’t make too many blunders, and he sent me a nice summary of his view on the topic in return.
The only thing I could do after reading it was to ask him for permission to do a copy-paste. Here it is:
Continuing the Streaming Telemetry saga, let’s focus on presentation formats and transport mechanisms.
I already mentioned three presentation formats: XML (used by NETCONF), JSON (used by RESTCONF) and Protocol Buffers (used by gRPC). Two of them are text-based, the third one (Protocol Buffers) is binary encoding not unlike ASN.1 BER used by SNMP. That can’t be good in a JSON-hyped world, right?
During the Campus Evolution with Cat9K presentation (I hope I got it right - the whole event was an absolute overload) the presenter mentioned the benefits of brand-new model-driven telemetry, which immediately caused me to put my academic hat on and state that we had model-driven telemetry for at least 30 years.
Don’t believe me? Have you ever looked at an SNMP MIB description? Did it look like random prose to you or did it seem to have some internal structure?
I don’t think I’ve ever been at a Tech Field Day event that’s been as intense as what we went through in the last few days at Cisco Live Europe – at least 17 different presentations in two days. It’s still all a blur and will take a long while to sort out.
One of the more interesting presentations we had during Tech Field Day Extra @ Cisco Live Berlin was coming from Paessler, a company developing PRTG, a little-known network monitoring software.
Monitoring SDN Networks is the featured webinar of June 2017, and in the featured video Terry Slattery (CCIE#1026) talks about network analysis of SDN.
If you’re a trial subscriber, log into my.ipspace.net, select the webinar from the first page, and watch the video marked with star… and if you’d like to try the ipSpace.net subscription register here.
One of the challenges of designing a controller-based solution is the transport network used to exchange information between controller and controlled devices. Can you do that in-band or is it better to have an out-of-band network (built with traditional components)? Terry Slattery explained some of the pros and cons in the Monitoring SDN Networks webinar.