Google applies SDN to configuration management
Google applies SDN to configuration management
It’s no secret that Google is largely responsible for sparking the software-defined networking (SDN) revolution. Tired of waiting for switch suppliers to separate control and data plane functionality in data center switches, the company built its own OpenFlow switch in 2010. Once Google went public with it, the networking industry took notice in a big way. Now Google is evangelizing the need to revolutionize the network management plane, too. The company announced earlier this summer that it intends to open up about its ideas for SDN management, and recently at LinuxCon an architect from the company gave a presentation outlining how Google thinks SDN can be applied to configuration management.
“SDN and automation are glaringly absent in the management plane,” Anees Shaikh, Network Architect, Google, told a packed session at an OpenDaylight mini summit that was held as part of LinuxCon in Chicago. “It looks to be more and more in the dark ages as we progress and put the spotlight on it.”
Most network operators manage their networks largely using scripting against proprietary command line interfaces (CLIs), said Shaikh, who has been working on the Google network architecture team for about six months. Before that he was Chief SDN Architect in the System Networking Division at IBM.
“Even large ISPs [Internet service providers] including ourselves are doing things in a largely traditional and decidedly non-SDN way,” he said.
The need for change
Network operators, including many TM Forum members, have realized this must change. Toward that end, the Forum’s Zero-touch Orchestration, Operations and Management (ZOOM) team is working on a new information model for delivering services end-to-end in hybrid environments, meaning networks that include both legacy and virtualized components, and it is developing new application program interfaces (APIs) to link network management and operational support systems with SDN controllers. Network management in service provider networks needs to move beyond the Simple Network Management Protocol (SNMP), which Shaikh joked is “no one’s favorite protocol” and is anything but simple.
“We are stuck with protocols that haven’t evolved into being easy to integrate into software systems,” he said. “We want to do more automated, systematic management of our networks. The question that we’re asking is: How can we take these SDN principles and really try to apply them to network management?”
Shaikh said that as a first step, Google has been working on applying SDN principles to configuration management. The company is developing an initial set of vendor-neutral configuration models for functions such as Border Gateway Protocol routing, virtual private networks and multiprotocol label switching. Google, which has adopted Yang as a data modeling language, is also is working on a data model for network topology. The company is sharing its work with other service providers for comment.
“The idea is to publish models and code jointly from a small set of users and invite participation and feedback,” Shaikh said. “Software-defined networking really requires software-defined operators,” he said.
According to Shaikh, Google’s view of a common data configuration model is one that: “There should be a base model that allows for vendor-specific configurations,” Shaikh explained.
- is standards-based;
- uses common naming and structure;
- is simple and limited, covering basic user cases that everyone agrees on; and
- provides defaults and constraints for validation.
Extending the Information Model
While Google is working on building a data model, TM Forum is working to extend the Frameworx Information Model to cover virtualized and hybrid environments. The Information Model allows service providers to construct end-to-end management views for network topology and node configurations in a multi-technology and multi-vendor environment.
“Notably the network and logical resource models in this framework support network management function [FCAPS] use cases, provide models for naming structures and provide support mechanisms for controlled vendor extensions,” said Dave Milham, Chief Architect, ZOOM.
During his presentation, Shaikh showed a slide explaining how Google views software-defined network configuration (see Figure below).
On the bottom of the stack on the left side of the diagram would be a protocol like OpenFlow, which is responsible for talking to devices programmatically. The operating system is a controller, such as OpenDaylight, which supports multiple southbound protocols, manages the state of the network from the control plane perspective and also exports to applications through northbound APIs.
“You need separation of what is configured on the device from what is actually authoritative configuration, which lives in a management system,” Shaikh explained. “This notion of centralized control requires a network-wide view – it cannot be device by device in isolation. It requires logical centralization." “What I think of in terms of application in the configuration world is really the intent,” Shaikh added. “Applications are intended to manipulate control state in the network at an abstract level. Similarly, configuration intent – what is it that I want to achieve in the network – can be thought of as the application. Operators are interacting directly with this notion of intent. They describe an intent they want to see the network configured to. Then the API they use is a basically a model of configuration.”
TM Forum’s ZOOM team is working on developing such APIs and has committed to delivering a program of work by the end of the year that includes best practice for YANG models so that they can support end-to-end management views across multiple network technologies and vendor implementations.
“TM Forum’s Integration Program has a track record in developing management interfaces with consistent design principles and patterns using a common Frameworx Information Model across a number integration technologies,” Milham said. “A common information model – notably network and logical resource models – turns out to be the core standard to drive individual API data model implementations and Yang is emerging as a popular technology.”
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