Start with Best Practices for Modeling and Managing Today's Network - Part 1
New Features, New Benefits
Network features and related policies can be mapped using these four constructs:
■ Domains: Apply configuration settings consistently across multiple devices. An example is a QoS configuration which may be different by business units, hence, different QoS domains would allow network engineers to assign QoS policies across all devices associated with specific business units in each region.
■ Features: Give the configuration settings for one device at a time, enabling functionality that the device can provide by itself. A good example is the configuration of a device-specific routing table where the device should forward incoming traffic.
■ Globals: Apply these configuration settings throughout the network; these are the same for every device in the network. A good example is NTP (network time protocol) where the central architecture team is defining the only NTP servers permissible for the network.
■ Custom: There will always be exceptions, so not everything may be practical to model in a general feature or domain concepts, especially specific exceptions to single devices only. For example, a specific set of Access Control Lists (ACLs) may only be needed on a single device. For these cases where no other dependencies with other features exist, just applying configuration data to a device may be acceptable.
Whatever network policy is needed can be built using a combination of these constructs. Inherent interdependencies can be flagged by network engineers early, so that a network management system can deploy them in the correct sequential order, optimally applying these features to individual devices as well as across the network to create the target policy. Abstracting network functionality into these types of models allows network engineers to re-focus on the actual network architecture and focus less on the mechanics of the management of configuration data. These lead to a number of benefits:
■ Any hardware, any manufacturer: How a device is configured is now based on how it should perform, by itself or in concert with other devices. As a result, the actual hardware itself, its specific OS/firmware or even the manufacturer no longer matters, as long as the device is capable of performing the desired functionality.
■ Logical separation: NetOps is logically separated from implementation and maintenance (DevOps). For example, architects can define the features, domains and global settings needed for a given network infrastructure, assemble them into logical groups and resolve any interdependencies. They can then be tested and validated by, for example, the security team. The assembled features, domains and globals are handed over to the operational team, who will deploy them onto the network and manage them over their lifecycle.
■ Communal wisdom: When networks are modeled through logical constructs, it allows for a wide exchange of best-practice reference designs based on common user requirements. Different teams of architects can exchange information about the models they use for specific network functionalities without having to revert to low-level configuration settings. This opens the possibility of creating network engineering communities that exchange specific models based on their desired use cases with clearly defined interdependencies and conflict resolution against other models.
Managing the Modern Network
What is needed to create a next-generation network management tool? Nothing less than the development of a sophisticated network-aware orchestration engine that is able to detect any interdependencies, resolve them and deploy network policies automatically over the network.
First, consider these non-technical challenges:
■ Users need to firmly believe that the logical network model will, in fact, result in the correct configuration of all devices in the network. Many network engineers are still most comfortable with command line interface (CLI) created from scripts and templates.
■ The primary focus of network engineers is on proper device configurations and ensuring the device is performing as intended. Any next-generation tools have been designed with a network engineering focus in mind, allowing network engineers to use the system with a much shorter learning curve and minimal programming expertise.
■ Get the buy-in of DevOps and NetOps teams, who may be skeptical to trust device configuration to a new management tool.
Technically speaking, here's what today's management tools should include:
■ Management to handle the high degree of customization needed.
■ Zero-touch provisioning so that the onboarding of new devices into the system is as fluid as possible, allowing generalist IT staff to install routers and trigger device provisioning automatically.
■ The ability to limit or flag unauthorized manual device configuration changes with automatic remediation when needed.
■ Configuration preview that allows dry runs of new configurations to understand all changes that may have to be performed, even on other network devices when needed.
■ Step-by-step verification of device provisioning actions with automatic revert on errors.
A New Approach
Organizations can bring their networks into present-day functionality with tools that provide complete abstraction of network functions while providing deeply integrated model interdependency verification, deployment previews and layer-by-layer provisioning. For example, replacing an existing device with a newer model, even if it's from a different vendor, can be detected and automatically provisioned. Such solutions that can resolve any potential conflicts and interdependencies, even across vendors, are becoming increasingly important as network devices are virtualized on common platforms and the individual strength of vendor-specific solutions are combined into one multi-vendor solution.
A model like this that addresses the entire stack provides clarity to architecture and implementation teams because the handoff points are well defined. This, in turn, leads to faster implementation of business requirements and higher reliability. Such a system creates quicker identification of and recovery from network outages, which increases customer confidence and satisfaction and saves money from unexpected downtime.
Dr. Stefan Dietrich is VP of Product Strategy at Glue Networks.