How Google Manages its SDN Network


(T) I attended this week a presentation at Google from one of the network architects Bikash Koley. The topic of the presentation was about how Google manages its SDN network. Google network is SDN-based from end-to-end. The network has many worldwide peering sites and a CDN for caching all the YouTube videos. It requires around 30,0000 configuration changes per month. Most of those configurations are necessary to both accommodate new network equipment to support the growth of the network and updates to the various protocol stacks. The SDN management plane has three building blocks: topology, configuration, and telemetry.

Topology describes the structure of the network. It is proprietary to Google although Google could open source it in the future.

The configuration of the network, mostly required to operate the protocols of the SDN control plane, is based on OpenConfig. it provides vendor-neutral configuration and operational state models. Configurations are modeled using the YANG language (See RFC 6020 for the complete specifications). Configuration data is encoded in protobuf (but also in XML or JSON) and pushed natively to the network elements through gRPC.

Google started recently to open source OpenConfig. AT&T first contributed to the source code and now many operators are also contributors to OpenConfig including Apple, BT, Comcast, Cox, Facebook, Google Level3, Microsoft, Verizon, and Yahoo.

OpenConfig initial focus has been on configurations for BGP routing and MPLS Traffic Engineering.

Telemetry provides the monitoring functions for the management plane. Network state changes are observed by analyzing time-series of the network elements information model which is modeled (as it is the case for the configuration of the control plane protocols) in Yang and encoded in protobuf. The telemetry module has a direct interface to both the control plane and the data plane.

For more details, see the following presentation: Bikash_Koley SDN_meetup May 2015

Note: The picture above is a Corsaire boat in the port of Saint-Malo.

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Categories: Networking