Why Data Models Rule the Enterprise Network World

Smitha Smitha
Smitha Smitha and Paul Merlo

Monday, April 25th, 2022

Read Time
3 min read

Managing enterprise networks with gear from multiple vendors is extremely complex. Enterprise IT administrators with hundreds, thousands, or even more networking devices and services to manage are turning to programmable and automated deployment, provisioning, and management to scale their operations without having to scale their costs. Using structured data models and programmable interfaces that talk directly to devices―bypassing the command line interface (CLI)―is also becoming an integral part of software-defined networking.

Data models offer a better way to manage multi-vendor enterprise networks. Here’s a look at how you can use both open-source models from OpenConfig or native data models, which are fully supported in Cisco IOS XE Software.

Why use OpenConfig?

OpenConfig is an effort by network operators in collaboration with vendors to build open, software-defined, vendor-neutral, and model-driven principles for network configuration and management. OpenConfig enables the use of:

  • Data models for configuration and management using Yang 1.0 that are vendor neutral
  • Streaming telemetry for monitoring and obtaining incremental updates (SNMP is passé), which enables a Pub/Sub interface that alerts the collector of changes almost as soon as they occur on the device

Figure 1 shows the OpenConfig models, which are published on GitHub.

Figure 1. OpenConfig Models

Major Support for OpenConfig

Many customers with Massively Scalable Data Centers (MSDCs), such as Microsoft, are very interested in OpenConfig as they run huge data centers with devices from multiple vendors. Various other networking vendors such as Juniper and Arista also support OpenConfig models.

If you’re a network operator struggling with configuring and managing a multi-vendor network, struggle no more—OpenConfig is a great way forward.

Vendor-neutral and Native Data Models

One path being explored by many operators is to use Google Remote Procedure Calls (gRPC), gRPC Network Management Interface (gNMI) as the network management protocol. Originally, gNMI didn’t support the use of anything other than OpenConfig models. Now that it does, many developers might not realize that and think that choosing gNMI will result in limited data model options. Cisco IOS XE has been ungraded to fully support both our native models and OpenConfig models when gNMI is the network management protocol.

Cisco has defined data models that are native to all enterprise gear running Cisco IOS XE and other Cisco IOS versions for data center and wireless environments. Other vendors have similar native data models for their equipment. The IETF has its own guidelines based on YANG data models for network topologies. So too does a consortium of service providers led by Google, whose use of OpenConfig has defined standardized, vendor-neutral data modeling schemas based on the operational use cases and requirements of multiple network operators.

Vendor neutral models define common attributes that should work across all vendors. However, the current reality is that despite the growing scope of these open, vendor-neutral models, many network operators still struggle to achieve complete coverage for all their configuration and operational data requirements.

At Cisco we have our own native data models that encompass our rich feature sets for all devices supported by IOS XE. Within every feature are most, if not all, of the attributes defined by IETF and OpenConfig, plus extra features that our customers find useful and haven’t yet been or won’t be added to vendor-neutral models.

With each passing release of Cisco IOS XE there has been significant and steady growth both in the number of native YANG models supported and in the number of configuration paths supported. The number of paths provides an insight into the vast feature coverage we have in IOS –XE. As of IOS XE release 17.5.1, there are approximately 232000 XPaths covering a diverse set of features ranging from newer ones like segment routing to older ones like Routing Information Protocol (RIP).

Complete information on Cisco IOSXE YANG model coverage can be found in the public GitHub repository. The information there is updated with data from every new IOS XE release.

For customers evaluating gNMI as their network management protocol it may feel like a dead-end when OpenConfig models are insufficient to handle a use case. It is important to understand that gNMI is not limited to OpenConfig models and vendors can make their native models available with gNMI as well.

With the mixed-schema approach operators can mix OpenConfig and native models without sacrificing many of the advantages of a model-driven approach to configuration and operational data. Operators can disambiguate the schema source using the gNMI “origin” fields defined by the network device vendor.

Note: All Cisco software platforms (IOS XE, IOS XR, NX-OS) will continue to support IETF, OpenConfig, and native models. There are legitimate needs for all three from our customers.