A Community Artist left an attention-grabbing comment on certainly one of my weblog posts:
It’s sort of complicated generally to see the digital twin (being a extremely good thought) by no means actually take off.
His comment prompted me to resurface a two-year-old draft itemizing a bunch of minor annoyances that make Networking Digital Twins extra of a PowerPoint challenge than a actuality.
Let’s begin with the simple ones:
- Since Dynamips ran out of platforms to emulate, I haven’t seen a digital machine (or container) that helps something aside from Ethernet interfaces. Which may not matter in 2025, however for those who occur to have some other know-how in your community, it’s a right away showstopper.
- Community working techniques packaged as digital machines usually have totally different interface names than the actual {hardware}. The one distributors I’ve seen coping with that had been Cumulus Linux, which might (being primarily based on Linux) merely rename the gadgets (Ethernet ports), and Arista EOS, the place you may specify the mapping of Linux interfaces into Arista EOS interface names with a JSON configuration file.
- Only a few digital machines that emulate chassis switches help you specify the road playing cards you wish to use. The one exception I’m conscious of is Nokia SR Linux and SR-OS.
- Digital machines often have a restricted variety of interfaces, whether or not because of VM limitations or limitations of the virtualization infrastructure. That might make it unattainable to reliably emulate giant core switches.
- RAM and CPU necessities: Some digital machines emulating bloated community gadgets require 4+ CPU cores and 16+ GB of RAM. However, other than Clabernetes, I haven’t seen any critical effort to construct a Digital Twin Infrastructure that will be capable to deploy the workload on a server cluster. It have to be nice enjoyable constructing a server that may emulate a big Nexus OS cloth.
However wait, we simply bought began. There’s the tiny element of information aircraft emulation. I heard of a single firm (NVIDIA) that claimed they’re making an attempt to emulate their ASICs in digital machines.
Anyway:
- Digital information aircraft performance usually doesn’t match the ASIC conduct (extra particulars, examples). Even worse, some digital machines can not cope with fundamental options like interface bandwidth. I don’t wish to understand how dependable QoS emulation is on platforms that do QoS in {hardware}.
- Printouts associated to the info aircraft performance most likely don’t match between digital machines and bodily {hardware}, making it unattainable to check any community automation resolution that depends on inspecting {hardware} particulars.
- Some control-plane protocols won’t work as anticipated (I had issues with some BFD implementations)
- Management-plane safety won’t work (I’m not courageous sufficient to strive it out)
- I by no means examined the complicated failover performance (comparable to TI-LFA), however I wouldn’t be stunned to seek out quirks.
Lengthy story brief: It seems to be like most distributors determined the first use case of the VM variations of their community gadgets is kicking the tires and getting acquainted with the platform. That’s superior, and I can’t let you know how essential it’s for somebody evaluating a brand new platform to realize some hands-on expertise with it. Nevertheless, there’s a really good distance between this use case and a dependable (and thus helpful) digital twin.
I hope the fact isn’t as bleak as what I can see from right here; ought to that be the case, please depart a remark.
Lastly, let’s handle the pair of elephants that was patiently ready within the nook of the room:
The generic I can use a digital twin to check modifications in my community thought is sadly as sound as I can transfer my VM all over the world to attenuate the latency for currently-active customers. Each of them look nice in PowerPoint, however match actuality as carefully as a spherical cow in a vacuum.
Revision Historical past
- 2025-06-19
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- Stefan de Kooter submitted a PR declaring which you can specify the emulated {hardware} configuration on SR-OS
- Charles Monson identified Arista’s interface mapping functionality.
