Participatory Networking: An API for Application Control of SDNs

This paper presents an API called PANE that is implemented by an OpenFlow controller that delegates read and write authority to the end users and allows applicants and end-hosts to control software-defined networking (SDN) bandwidth. In a common network or SDN, the absence of security guarantees and limited authorities, participatory networks would be places of anarchy. To be usable, such networks must provide isolation for their independent principals, preventing malicious users from consuming and controlling the bandwidth, dropping packets, or worse. While isolation could be provided through network virtualization, the authors believe that is not always the right abstraction as it hides the fundamentally shared aspect of networks. PANE delegates read and write authority, with optional restrictions, from the network's administrators to the users, or applications and hosts acting on their behalf. This API have to safely decompose control and visibility of the network, and to resolve conflicts between participants and across requests.

PANE is designed for networks within a single administrative domain including corporate WANs, datacenters, campus or enterprise networks, and home networks. In such networks, there is, logically, a single owner from which authority can be delegated. Conflicts arises naturally in a participatory network, as PANE is designed to allow multiple, distributed principals to author the network configuration. PANE represents the user requests in a Hierarchical Flow Tables (HFT), and to resolve conflicts the policies take a conflict resolution operator that takes as input two conflicting requests, and return a single resolved request. For instance, if we have requests that demand bandwidth of 10Mbps and 30Mbps, this conflict is resolved by guaranteeing the higher bandwidth.

PANE uses multiple types allow HFTs to resolve different types of conflicts using independent logic: 1. resolve conflicts between requests within the same share 2. resolve conflicts between conflicting requests in parent and child shares, 3. and resolve conflicts between sibling shares.

A network can be partitioned due to a failure in the switches or routers. PANE controller considers two types of failures: the failure of network elements, and the failure of the controller itself.

In the first case, when a switch or link fails, or when a link's configuration changes, the PANE runtime must recompile the policy tree to new individual switch flow tables, as previously used paths may no longer be available or acceptable. In the second case, PAN can keep a database-like persistent log of accepted requests that are periodically compacted by removing the requests that expired. Upon a recovery, PANE controller can restore its state.

They tested some applications with PANE to check the benefits of the solution. One of the test was made with Hadoop MapReduce, where they augmented Hadoop 2.0.3 to work with PANE API. By using PANE, Hadoop was able to reserve guaranteed bandwidth for some operations like the shuffle and sort, and the writing the final output. The first set of reservations occurs during the shuffle where each reducer reserves bandwidth for transferring data from the mappers. The second set of reservations reserves bandwidth when writing the final output. These few reservations improved the overall performance by 19%.