Multi-tenant-style VLAN support is now enabled in Switchboard, so in addition to dynamically configuring un-tagged routes, users can also request that Switchboard setup routes over specific VLANs. After the user request has been approved by the appropriate subnet/ip owners, the route is configured. This wraps up phase I of our VLAN support strategy.

How it works

A controller running the Ryu REST Router code can support VLAN tagged traffic, and on the surface this looks simple to support – just add the VLAN tag parameter to the end of the REST URL.
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Now that we can demonstrate the latest version of Switchboard working with real hardware (from two different vendors) on the production campus network, it seemed like time to celebrate the event with an update on Switchboard and some screen captures of a demo walkthrough.

bypass network configured connecting 10.138.96.17 and 152.3.9.2

Maintaining State Across SDN Controller Restarts

User-driven reconfiguration of the SDN network means that we have an interesting problem: how to we restore the state of the network in the event of a reboot (or crash) of the SDN controller?

Switchboard addresses this issue by caching the commands it has issued to the controller in a mysql database table. To restore the state of the SDN network after a controller restart, we simply replay the commands in order. Since these commands include user-requested route adds and deletes, getting back to a given state is straightforward.

To automate recovery from SDN controller restarts, the controller startup script could wait until the controller has started up, then make a REST request to Switchboard to trigger playback of the command cache and so restore state.

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What is Switchboard?

Switchboard is a web application designed to allow researchers to quickly set up and tear down links across an SDN network that bypasses the core campus network — think of this as a high-speed expressway that you might take to avoid the congestion of  downtown.

To do this, Switchboard allows authorized users to request links (routes) to be configured across an SDN network. Because links may cross administrative boundaries, Switchboard supports a simple workflow for approving link requests. After a given link request has been approved, Switchboard makes REST web services calls to an SDN controller running the RYU REST web services controller code to configure the SDN switches.

Switchboard is a user-facing service for researchers and others who are not SDN network experts that

• accepts users’ network configuration change requests
• routes the requests for authorization
• logs approvals of requests
• updates the configuration of the SDN network
• logs changes to the SDN network configuration

How does Switchboard work?

To properly authorize link requests, Switchboard maintains in it’s database, a map of users/groups who can authorize link requests for specific IP addresses/subnets. This map is created by the Switchboard application administrators, although it could also be driven from an external database of roles and address space ownership.

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