Why no YANG??

I was at Cisco Live in Berlin last week, and I came away with a question: why no YANG?


Here is a YANG model represented in YIN—this one describes an interface in Quagga, and is easy to read:

YANG can be expressed in many ways, such as YIN, or in a model format (which is still easy to read), or in json format. This is an example of HTML, taken from the Vimeo site:

The YIN representation of YANG is XML, and XML is also a superset of HTML.

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  1. Abdel-moniem E. REZK 1 March 2017 at 1:28 pm


    Recently I was teaching NETCONF and YANG model with Cisco NSO as well using it with emerging controller like OpenDay light, I faced with the same question on why do we have to introduce YANG as a model and answered very similarly pointing out the IETF effort in having NETCONF and YANG model in place and what lead to it. Several tools as well to convert YANG to HTML with collapsed view or simply ASCII (pyang tool built with python) or convert it to UML as well …

    I believe SNMP will not go for now, especially in monitoring (GET process) but it might be replaced soon.

    I agree that YANG modelling should be adopted more and more by NMS and OSS/BSS providers… Especially it shouldn’t be an option in the future. Network Architect and Engineers should promote YANG modelling I totally agree



    • Russ 1 March 2017 at 3:39 pm

      Thanks for stopping by… I think it will take a while for the market to shift over, but the benefits are real in this case… Thanks for helping push things along.



  2. Abdel-moniem E. REZK 1 March 2017 at 1:29 pm

    I liked the embedded Video Blogging idea as well. I hope you do it more often


    • Russ 1 March 2017 at 3:39 pm

      Thanks! I’m still playing with the audio and the like, but I’m trying to figure the video bits out, as I think I might do other video format stuff in the future.



  3. Christian 2 March 2017 at 3:26 pm

    Is YANG a suitable mechanism to monitor a network as well as configure a network? To collect telemetry data?

    • Russ 2 March 2017 at 8:50 pm

      Yes — you can use YANG for telemetry data. In fact, I know of several providers already using it this way.

      Thanks for reading, and stopping by!



  4. George Davitiani 2 March 2017 at 9:16 pm

    +100 for more videos!

  5. Sasanka 3 March 2017 at 3:56 am

    I agree ,vendor should be asked to support YANG , as SNMP already lived it’s day.

  6. G 4 March 2017 at 8:09 pm

    Cisco supports YANG, (NSO, XR, NXOS) but I agree some vendors do need to catch up. Chicken and the egg situation I believe. Until there are more common models, its an incomplete solution and management vendors won’t invest in this area.

    • Russ 5 March 2017 at 4:53 pm

      The last time I looked, Cisco’s support of YANG was pretty minimal–a lot of “wrap the existing configuration into a text field…” But it’s not just the hardware vendors, it’s the network management folks, too.

      Thanks for stopping by!



  7. Jason Belk 8 March 2017 at 3:49 pm

    Hey Russ,

    It has been a while! I hope you are doing well.

    I totally sympathize with what you are communicating. We are just starting to model our config templates in Yang and have just recently been trained in Yang (through the tail-f NSO/NCS training). I think two things that have made it difficult to ramp up using Yang (speaking for usage outside the Data Center, which is my area of experience):
    1. Yang documentation still seems pretty limited. There are no books (that I could find) that give an introduction to Yang. A quick Amazon search for Yang give no results related to network engineering. The only place I could find Yang walkthroughs were on the RFC 6020: https://tools.ietf.org/pdf/rfc6020.pdf and the tail-f NSO trainings: http://www.slideshare.net/tailfsystems/presentations

    2. Cisco IOS does not support Yang (from what I understand only IOS XE / XR / NXOS), this is promised to be forthcoming, but not yet here. Tail-f’s Cisco’s NSO does the translation for you on IOS devices that don’t do Yang, but native Yang support is still not pervasive.

    As a blossoming DevOps engineer, who works with Python, I want to use Yang, and trying to learn it. The journey so far has not been simple and easy though. I agree Yang syntax is relatively easy to understand, but I think most people get scared off before they actually even look at Yang examples.

    • Russ 8 March 2017 at 5:30 pm

      Jason —

      Thanks for stopping by and commenting — you bring up a lot of good points! There is little written about YANG — maybe I should do some posts on this, just to help the community out, or a get someone who’s a real expert to do a webinar with Ivan. I do tend to people get scared off before they even start looking at it… It doesn’t help that there are a lot of “big names” out there who are down on YANG. It’s infectious when someone who’s widely respected says “YANG is horrible,” etc.



  8. Alvaro 11 March 2017 at 10:10 am

    Hello Russ,

    Great video. I agree with prior comments, YANG is kind of confusive for people because of the lack of clear and simple documentation about it. Until now I thought Cisco, Juniper, Huawei, etc. did support YANG, but it’s not directly YANG, isn’t it? Like Junos with it’s python pyez, which uses YAML. I understand many vendors are going to support openconfig, would this solve the issue?

    There are so many terms I get confused. Maybe other people also know netconf, yang, openconfig…, but have never seen a book or video that really explains how it all fits together and what differences there are. For example, what would be the difference of Junos supporting yang natively than it using netconf and yaml through python or ruby? That kind of questions come to mind.

    Thanks for the excellent videos Russ!

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